Can Motivation Overcome the Mental Impairment from Being High?
Money incentives partially reduced cannabis-induced cognitive impairment, while experienced users showed no behavioral tolerance advantage over first-time users.
Cognition research
Explore published research on cognition, including study methods and limitations.
Mixing Marijuana and Amphetamines: Heart Effects Added Up but Cognitive Impairment Came from the Weed
Marijuana and amphetamine produced additive cardiovascular effects but psychomotor impairment came only from marijuana, with no stimulant counteraction.
Alcohol Disrupted Eye Tracking in Ways That Cannabis Did Not
Alcohol impaired smooth eye tracking at multiple doses. Cannabis produced no measurable effect on the same visual tracking tasks in experienced users.
Combining Cannabis With Amphetamines Did Not Make Impairment Worse Than Cannabis Alone
Combining cannabis with dextroamphetamine produced impairment similar to cannabis alone. The stimulant did not counteract cannabis-related motor deficits.
Two Months of Daily Cannabis Use Did Not Damage Immune Function in Healthy Adults
Twelve adults smoked cannabis daily for 64 days under hospital observation. Immune function markers remained normal or improved throughout the study period.
Cannabis-Related Cognitive Deficits Were Smallest in People Who Started With Lower Baseline Abilities
Among 1,689 Egyptian men, cannabis users showed cognitive deficits compared to non-users, but the gap was smallest among illiterate, rural, and older participants.
A Major 1986 Review Found Cannabis's Greatest Health Concern Was Its Effect on Young Users
A major 1986 pharmacological review found cannabis's greatest health concern was its impact on youth development, while finding no proven brain damage and limited physical dependence in adults.
Chronic THC Altered Rat Hippocampus Structure, but Three Months of Exposure Was Needed
Animal studies showed chronic THC altered the hippocampus in rats, but required at least 3 months of exposure in young animals. Monkey studies did not consistently replicate these findings.
Long-Term Cannabis Users Showed Measurably Impaired Ability to Filter Irrelevant Information
Brain recordings showed long-term cannabis users processed irrelevant information that non-users filtered out, indicating impaired attentional resource allocation.
Years of Cannabis Use Impaired Attention Filtering, While Frequency of Use Slowed Processing Speed
Brain recordings revealed two distinct cannabis-related deficits: attentional filtering worsened with years of use, while processing speed slowed with frequency of use, suggesting different mechanisms.
Prenatal Cigarette Exposure Hurt Children's Reading and Language, but Prenatal Marijuana Did Not
In 131 children followed from birth, prenatal cigarette exposure was linked to lower reading and language scores in a dose-dependent pattern, while prenatal marijuana exposure showed no significant effect.
Alcohol and Marijuana Produced Similar Impairment on Memory and Processing Tasks at Comparable Doses
At controlled doses, alcohol and marijuana produced identical perceived impairment and comparable deficits on memory and processing speed tests. Neither affected reaction time.
A Major Review Found THC Caused Cell Death in the Hippocampus and Shared Reward Pathways With Other Drugs of Abuse
A major review found THC caused cell death in the hippocampus, produced persistent cognitive deficits, and activated the same dopamine reward pathways as morphine, alcohol, and nicotine.
Starting Cannabis Before Age 16 Caused Lasting Visual Scanning Deficits That Later Users Did Not Show
Among 99 cannabis users, only those who started before age 16 showed lasting visual scanning deficits. Age of onset was the sole predictor, not total amount used or current intoxication.
Ecstasy Users Showed Cognitive Decline While Cannabis-Only Users Did Not Differ From Non-Users
Ecstasy users showed cognitive impairment on attention, memory, and intelligence measures, while cannabis-only users performed identically to drug-free controls.
Both Cannabis and Ecstasy Users Had Impaired Verbal Memory, but Only Ecstasy Users Had Delayed Memory Deficits
Both cannabis and ecstasy users had impaired verbal memory versus controls. Only ecstasy users showed additional delayed memory deficits. Neither group was aware of their cognitive impairment.
Does THC Treatment for Tourette Syndrome Cause Cognitive Problems?
A small randomized trial found that single-dose THC (5-10 mg) for Tourette syndrome did not impair cognition across multiple domains, unlike findings from recreational cannabis use studies.
Does the Brain Build Tolerance to THC's Memory-Disrupting Effects?
Chronic THC treatment in rats did not produce tolerance to memory impairment or hippocampal acetylcholine reduction, with both effects mediated by CB1 receptors but operating on different timescales.
How Cannabinoids Affect the Brain: Receptors, Memory, Movement, and Appetite
Comprehensive review mapping how cannabinoids affect different brain regions: memory in the hippocampus, movement and reward in the basal ganglia, appetite in the hypothalamus, with neuroprotective properties.
The Brain's Own Cannabis System: Its Role in Memory and Drug Dependence
Review finding that blocking or removing CB1 receptors enhanced memory performance, suggesting the endocannabinoid system normally constrains memory formation, while also modulating opioid dependence.
The First Controlled Trial of THC for Tourette Syndrome Tics
First RCT showing THC significantly reduces tics and OCD symptoms in Tourette syndrome, with effects linked to the 11-OH-THC metabolite rather than THC itself.
Cannabis and the Brain: A Comprehensive Review Published in Brain
Major Brain journal review finding cannabis cognitive impairments appear reversible with little evidence of brain pathology, and limited evidence for causal psychiatric illness links.
Cannabis Users Process Attention Differently: Brain Wave Evidence
Brain wave study showing chronic cannabis users processed auditory attention differently, with reduced P3 responses to targets and greater effects in early-onset users, undetected by standard tests.
Cannabis Users See Depth Illusions Differently, Similar to People with Schizophrenia
Study finding cannabis users showed reduced depth inversion illusion scores, a pattern shared with schizophrenia patients, undetected by standard cognitive tests, suggesting subtle visual processing changes.
Mental Health Problems in Ecstasy Users: Was It Actually the Cannabis?
Combined cross-sectional and longitudinal study finding that psychiatric symptoms in ecstasy users were predominantly attributable to cannabis use, not ecstasy, with cessation of cannabis but not ecstasy predicting symptom remission.
Brain Scans Show Cannabis Users Work Harder to Remember: An fMRI Study
fMRI study showing heavy cannabis users activated more brain regions and recruited additional areas not normally used for spatial memory, suggesting neural compensation for subtle deficits.
Brain Scans of Young Adults Exposed to Cannabis Before Birth Show Lasting Changes
fMRI study showing young adults prenatally exposed to marijuana had increased brain activation during impulse control tasks and more errors, with effects persisting after controlling for current drug use.
Very Heavy Cannabis Users Still Showed Decision-Making Deficits and Brain Changes After 25 Days Abstinent
PET imaging study found heavy marijuana users (53-84 joints/week) still had brain activity changes and decision-making deficits after 25 days abstinent, while moderate users performed like non-users.
Brain Scans Show Chronic Cannabis Smokers Use Different Brain Pathways During Impulse Control Tasks
fMRI pilot study found chronic cannabis smokers used different, more diffuse brain activation patterns during an impulse control task, despite performing within normal limits.
THC Was the Primary Active Ingredient in Marijuana While CBC and CBD Concentrations Made No Difference
Controlled study of 23 marijuana users found varying CBC and CBD concentrations did not change the effects of smoked marijuana, confirming THC as the primary active ingredient.
Cocaine-Dependent People Who Also Used Cannabis Showed Reduced Brain Stress Responses
fMRI study found cocaine-dependent individuals who also used cannabis showed decreased frontal cortex activation during emotional stress, even after 15+ days of abstinence.
Cannabis Impairs Attention and Memory While Stimulants Affect Speed and Flexibility
Comparative review found cannabis primarily impairs attention and memory, stimulants affect processing speed and flexibility, and heroin impacts impulse control, with severity increasing with heavier use.
Three-Year Follow-Up: Cannabis Use Declined in Aboriginal Communities But Users Had More Hallucinations and Suicidal Thoughts
Three-year follow-up in Aboriginal communities found cannabis use decreased overall, but persistent users had higher rates of hallucinations, suicidal thoughts, and imprisonment.
CBD-Rich Cannabis Extract Could Not Reverse Memory Deficits Caused by Non-Cannabinoid Drugs in Rats
CBD-rich cannabis extract reversed THC-induced memory deficits but failed to reverse memory impairments caused by anticholinergic or antiglutamatergic drugs, suggesting CBD's effects are cannabinoid-system specific.
Using Cannabis With Ecstasy Did Not Protect Against Ecstasy-Related Cognitive Impairment
Reanalysis found people who used cannabis and ecstasy together had the same cognitive impairments as ecstasy-only users, showing no neuroprotective benefit from concurrent cannabis use.
Frequent Cannabis Users Showed Normal Working Memory and Attention After One Week of Abstinence
fMRI study of 10 moderate cannabis users after 1 week abstinent found normal working memory and attention performance, with only subtle brain activity changes in one parietal region.
Brain Imaging Review: Cannabis Does Not Damage Brain Structure But Changes How It Functions
Systematic review found no consistent structural brain damage from chronic cannabis use, but functional changes including altered cerebellar/frontal activity and compensatory activation during cognitive tasks.
Study Identifies THC Blood Levels of 2-5 ng/ml as the Threshold Where Driving Impairment Begins
Controlled study of 20 cannabis users found impairment began at 2-5 ng/ml serum THC, with 75-90% impaired at 5-10 ng/ml and 100% above 30 ng/ml, providing a framework for driving limits.
Comprehensive Review: THC Impairs Memory by Disrupting Encoding, Consolidation, and Retrieval
Review found THC transiently impairs memory for new information (not existing memories) in a dose-dependent manner, by disrupting encoding, consolidation, and retrieval through multiple neurotransmitter systems.
Young Adults Exposed to Cannabis Before Birth Showed Altered Brain Activity During Memory Tasks
fMRI study of 18-22 year olds from a 20-year longitudinal study found altered brain activation during memory tasks in those prenatally exposed to marijuana, despite normal task performance.
Review of Nicotine and Cannabis Interactions: Reinforcement May Be Enhanced When Used Together
Review of nicotine-cannabis interactions found co-use may enhance reinforcing and anxiolytic effects while having opposite effects on appetite and cognition, with adolescent co-use being a major concern.
Cannabis Users Showed Lower Alertness and Slower Cognition at Work But No More Workplace Errors
Study found cannabis users had lower alertness and slower cognition in work-related testing but did not report more workplace errors, with effects showing "hangover" and fatigue-related patterns.
Brain Imaging Studies Show Altered Neural Activity in Regular Cannabis Users
Review of brain imaging studies found that chronic cannabis users show consistently altered brain function during cognitive tasks, even without clear structural damage.
Teen Cannabis Users Showed Memory Problems That Surfaced During Nicotine Withdrawal
Teen cannabis+tobacco users showed verbal memory deficits and disrupted brain connectivity that only appeared during nicotine withdrawal, suggesting cannabis may damage memory circuits that nicotine temporarily masks.
Frequent Cannabis Users Showed Less Brain Activity During Memory Tasks Despite Normal Performance
Regular cannabis users showed lower hippocampal brain activity during memory tasks than non-users but performed just as well, with no structural brain differences detected.
Cannabis Extract With CBD Boosted Auditory Brain Responses While Pure THC Alone Did Not
Cannabis extract with CBD enhanced automatic brain responses to auditory changes, while pure THC alone did not, suggesting CBD may protect cognitive processing.
A Case of Suicide Attempt Linked to Cognitive Decline From Polysubstance Use
Case report of a 30-year-old whose polysubstance use (cannabis, MDMA, cocaine) led to cognitive decline, functional impairment, depression, and a suicide attempt.
Brain Imaging Found Structural Damage in the Corpus Callosum of Heavy Marijuana Users Who Started Young
Brain imaging of 11 heavy marijuana users who started in adolescence found structural white matter damage in the corpus callosum connecting the prefrontal cortices.
THC and CBD Affected Different Brain Regions During a Self-Control Task
fMRI study found THC weakened brain activation in impulse control regions (right frontal, anterior cingulate) while CBD affected entirely different areas, independent of intoxication.
Ecstasy Polydrug Users Showed Mild Cognitive Decline Over a Year, With a Paradoxical Cannabis Finding
Year-long study found ecstasy polydrug users showed mild cognitive decline while cannabis was paradoxically linked to faster brain processing speed on EEG measures.
Olanzapine Reversed THC-Induced Memory Impairment in Rats, but Haloperidol Did Not
Olanzapine reversed THC-induced spatial memory impairment in rats by restoring hippocampal acetylcholine levels, while haloperidol had no effect at any dose tested.
Cannabis Users Showed Opposite Brain Activity Patterns During Memory: Too Much in One Region, Too Little in Others
fMRI study found cannabis users showed opposite brain patterns during memory: reduced frontal activation alongside increased parahippocampal activity, suggesting compensation for functional deficits.
THC Reduced Brain Attention Responses, and CBD Didn't Reverse It in This Study
Crossover study found THC reduced the P300 attention brain wave, and a cannabis extract with CBD failed to reverse this effect, complicating the "CBD counteracts THC" narrative.
Pubertal Rats Showed Worse and More Lasting Effects From Cannabinoids Than Adult Rats
Pubertal rats given cannabinoids for 25 days showed persistent memory and social deficits lasting at least 15 days after stopping, while adult rats showed milder, more reversible effects.
Sativex Did Not Cause Psychiatric Problems or Cognitive Decline in Cannabis-Naive MS Patients
Crossover trial of 17 cannabis-naive MS patients found Sativex caused no psychiatric problems or cognitive decline at therapeutic doses, though higher THC blood levels correlated with subtle psychological symptom scores.
How THC and CBD Affect Brain Activity During Learning
THC disrupted brain activation in the parahippocampal gyrus and ventrostriatum during verbal learning, with ventrostriatal changes correlating with psychotic symptoms. CBD had no such effects.
Cannabis both calms and panics — the biphasic dose-response explains why the same drug produces opposite anxiety effects
Frequent use and anxiety often appear together, but this 2009 review could not pin down cause and effect.
Chronic Cannabis Users Had Reduced Ability to Notice Their Own Errors
Chronic cannabis users showed normal inhibitory control but significantly reduced awareness of their own errors, linked to reduced activation in the anterior cingulate cortex and right insula.
Higher THC Doses Caused Greater Cognitive and Motor Impairment in a Dose-Dependent Pattern
In 24 non-daily users, cognitive and motor impairment increased linearly with THC dose (up to 69 mg), but some individuals showed no motor impairment even at blood THC above 40 ng/mL.
Even Moderate Cannabis and Ecstasy Use Was Linked to Poorer Memory in Young Adults
In 284 population-sampled young adults, moderate cannabis and ecstasy use was associated with dose-related episodic memory decrements and increased attention lapses, though effect sizes were small.
Cannabis Addiction: How the Brain Rewiring of Chronic Use Creates Dependence
A literature review described cannabis addiction as a chronic brain disease involving dopamine and serotonin pathways, with chronic use producing lasting effects on cognitive and reward brain circuits.
What Heavy Teen Marijuana Use Was Linked To: Slower Thinking, Subtle Brain Differences, and Poorer Sleep
Heavy teen marijuana use was linked to modest cognitive disadvantages, subtle brain differences, and poorer sleep. Some changes persisted past a month and sometimes resolved by three months of abstinence.
THC Impairs Long-Term Memory by Hijacking a Protein Synthesis Pathway in the Hippocampus
THC impaired long-term memory in mice by activating the mTOR/p70S6K protein synthesis pathway in the hippocampus through CB1 receptors on inhibitory neurons, an effect blocked by rapamycin.
Heavy Cannabis Users Showed Much Less Cognitive Impairment from THC Than Occasional Users
After smoking the same THC dose, occasional cannabis users were impaired on 3 of 4 cognitive tasks while heavy users showed impairment only on motor inhibition at high blood levels, demonstrating functional tolerance.
Ecstasy Users Had Worse Memory Than Controls or Cannabis Users, With Distinct Brain Changes
Ecstasy users showed worse memory performance and distinct brain activation changes compared to both controls and cannabis users, though some neural effects overlapped between ecstasy and cannabis groups.
How Cannabis-Impaired Driving Differs From Drunk Driving
Cannabis impaired automatic driving functions and prompted compensatory behavior, while alcohol impaired complex tasks without compensation. Combining both eliminated compensation and multiplied impairment.
Adolescent Cannabis Users Needed More Brain Effort to Handle Conflicting Information
Young adults with adolescent cannabis use showed worse executive attention performance and stronger right prefrontal brain activation, suggesting less efficient attentional processing.
Long-Term Cannabis Users Showed Altered Brain Patterns During Memory Tasks
Chronic cannabis users (17 years average) showed altered brain electrical patterns during memory encoding, with greater changes linked to longer use and earlier onset.
Long-Term Cannabis Users Had More Errors and Altered Brain Responses When Processing Conflicting Information
Chronic cannabis users showed more Stroop conflict errors and altered brain electrical patterns during conflict resolution, with earlier use onset predicting worse performance.
How Often You Use Cannabis Matters More for Memory-Related Brain Function Than How Long You Have Used
Among 42 cannabis users, higher use frequency was specifically linked to increased parahippocampal brain activation during memory encoding, while duration and age of onset showed no effect on this region.
Starting Cannabis Before Age 16 Was Linked to Less Efficient Brain Function During Working Memory
Cannabis users who started before age 16 showed increased brain activation during working memory tasks compared to later-onset users, independent of total use, suggesting less efficient cortical processing.
THC and CBD Had Opposite Effects on Brain Function Across Multiple Tasks, and CBD Blocked THC Psychosis
THC and CBD had opposite effects on brain activation in the striatum, hippocampus, amygdala, and cortex across four cognitive tasks, and CBD pretreatment blocked THC-induced psychosis in 6 volunteers.
Teen Cannabis Users Showed Memory Recovery After Two Weeks of Abstinence but Attention Problems Persisted
Adolescent cannabis users showed memory recovery after 2-3 weeks of abstinence but attention accuracy remained impaired, suggesting different recovery timelines for different cognitive functions.
Cannabis Impaired Simulated Driving More Than Alcohol at the Doses Tested, Regardless of Experience
In a simulator, high-dose cannabis impaired multiple driving measures while alcohol at moderate doses had fewer effects. Cannabis decreased speed while alcohol slightly increased it, with no synergistic effects at tested doses.
Heavy drinking teens had worse memory, but not if they also used marijuana
Among 130 teens, heavy drinking predicted worse verbal memory, but only in those who did not also use marijuana.
Brain imaging studies show cannabis affects brain function more than brain structure
Systematic review of 41 brain imaging studies found cannabis affected brain function, especially prefrontal blood flow, but caused minimal structural changes.
Blocking cannabinoid receptors reversed memory problems caused by ecstasy withdrawal in mice
Blocking CB1 cannabinoid receptors reversed memory impairment during ecstasy withdrawal in mice, linked to hippocampal CB1 receptor upregulation.
Heavy cannabis users were slower at recognizing facial emotions
Heavy cannabis users were slower at recognizing dynamic facial emotions, requiring greater intensity before identifying sadness, anger, and happiness.
Recreational drug users (mainly ecstasy and cannabis) needed more brain effort for impulse control
fMRI showed recreational drug users (ecstasy/cannabis) needed more brain activation for impulse control despite normal task performance.
Schizophrenia patients who used cannabis actually had better cognitive function than non-users
First-episode schizophrenia patients who used cannabis showed better attention and executive function than non-users, both initially and after one year.
Cannabis-dependent people with depression had worse social functioning but surprisingly better cognition on some tests
Cannabis-dependent people with depression had worse social functioning but performed better on some cognitive tests than those without depression.
Heavy cannabis-using adolescents had smaller hippocampi even after nearly 7 months of abstinence
Heavy cannabis-using adolescents had smaller hippocampi than controls even after 6.7 months of abstinence, with volume correlated to amount of prior use.
Case study tracked executive function recovery over 12 weeks of cannabis abstinence
Case report tracked executive function from 24 hours to 12 weeks of cannabis abstinence, showing progressive cognitive improvement with clinical implications for treatment.
Just seeing marijuana-related images boosted creative problem-solving in people who believed marijuana enhances creativity
Seeing marijuana-related images improved creative problem-solving in people who expected marijuana to boost creativity, without any actual drug consumption.
MS patients who used cannabis performed worse on cognitive tests and were twice as likely to be cognitively impaired
MS patients who used cannabis performed significantly worse on cognitive tests across multiple domains and were twice as likely to be globally cognitively impaired.
Male cannabis users had slower motor skills and shifted brain activation patterns, linked to higher cortisol levels
Male cannabis users had slower motor skills and shifted brain activation from visual to executive regions, with elevated cortisol levels potentially mediating these effects.
Heavy high-potency cannabis smokers reported visual disturbances lasting months after quitting
Eight heavy high-potency cannabis-dependent smokers reported visual flashbacks including illusions and color distortions persisting 3-6 months after quitting.
What happens when people use both MDMA and cannabis together
Review of 23 studies found MDMA and cannabis co-use produced additive memory deficits, involving CB1-serotonin-dopamine interactions.
THC reduced the brain's error-detection signal in healthy volunteers
THC significantly reduced the brain's error-detection signal (ERN) in 10 healthy volunteers without affecting simple task performance.
A gene variant in the cannabinoid receptor influenced how THC affected brain attention signals
A cannabinoid receptor gene variant influenced how THC affected attention-related brain waves, with CBD in cannabis extract appearing to buffer the effect.
Brain imaging revealed the insula plays a key role in the THC "high"
Brain imaging showed THC increased blood flow and activity in the insula, linking this body-awareness region to the subjective experience of being "high."
Three Nights Without Cannabis Disrupted Sleep. Extended-release Zolpidem Blunted Much of It.
Three nights off cannabis cut sleep efficiency and total sleep time and shifted REM. Extended-release zolpidem restored efficiency but did not shorten time to fall asleep.
THC and CBD had opposite effects on brain areas that process sound and vision
Brain imaging showed THC and CBD had opposite effects on auditory processing regions, with THC's disruption correlating with psychotic symptoms.
THC-dependent mice showed memory problems during withdrawal, some lasting months
Chronic cannabinoid exposure during rat adolescence caused temporary general cognitive impairment but spatial memory deficits lasting at least 75 days.
Late-adolescent rats given chronic cannabinoids showed lasting spatial memory problems
Late-adolescent cannabinoid exposure in rats produced recoverable general cognitive deficits but persistent spatial memory impairment lasting at least 75 days.
Brain scans predicted which heavy cannabis users would develop worse problems six months later
Brain activity in cognitive control regions predicted which heavy cannabis users would develop worse problems over 6 months, beyond what craving alone predicted.
Cannabis impairs working memory through brain support cells, not neurons directly
Landmark Cell paper showing cannabis impairs working memory through CB1 receptors on astrocytes (support cells), not on neurons directly.
Long-term cannabis users showed increased brain connectivity that may compensate for impairment
Long-term cannabis users showed normal cognitive performance but increased brain connectivity between control and attention regions, suggesting neural compensation.
Teen marijuana users had reduced brain blood flow, but it normalized after 4 weeks of abstinence
Teen marijuana users showed reduced brain blood flow in multiple regions, but all differences disappeared after 4 weeks of confirmed abstinence.
Cannabis users with first-episode schizophrenia had earlier psychosis but better starting cognition
Cannabis-using first-episode schizophrenia patients had earlier psychosis onset but better cognition, with 75% quitting cannabis spontaneously over follow-up.
Schizophrenia patients who previously used cannabis showed different brain activation patterns during cognitive tasks
Schizophrenia patients with cannabis history showed better task-related brain activation and less default-mode activity at rest than non-using patients.
How cannabinoids disrupt memory formation: they suppress the brain's replay signals
Cannabinoids suppressed hippocampal sharp wave-ripples essential for memory consolidation by selectively inhibiting excitatory glutamate signaling.
From Teen Years to 38: Heavy, Long-Term Cannabis Use Tracked With Lower Cognitive Scores
The most famous and debated cannabis study: 1,037 New Zealanders followed from birth showed up to 8 IQ points of decline with persistent adolescent-onset use — but subsequent twin studies and meta-analyses suggest the true effect is smaller and partly confounded.
Caffeine Made THC's Memory-Impairing Effects Worse, Not Better, in Rats
In rats, caffeine did not offset THC's memory effects but actually worsened them, with a subthreshold THC dose impairing memory when combined with caffeine.
Runner's High Has an Endocannabinoid Signature in Humans. Dogs Show It Too.
High-intensity running raised blood endocannabinoids in humans and dogs, not in ferrets and not during walking.
Chronic Cannabis Users Show Brain Activation Changes in Social Thinking That Resemble Psychosis Risk Patterns
Brain imaging found chronic cannabis users had altered activation in social cognition regions, matching patterns seen in psychosis-risk populations.
Cannabis Boosted Creative Thinking in Less Creative People but Also Increased Psychosis-Like Symptoms
Cannabis improved verbal fluency in people with low baseline creativity while increasing psychosis-like symptoms in all users.
The Endocannabinoid System: A Master Regulator of Brain Health and Disease
Overview described the endocannabinoid system as a master regulator involved in neuroprotection, pain, memory, neurogenesis, and immune function.
Former Cannabis Users Recovered Learning Ability but Still Had Timing Problems in a Brain Task
Former cannabis users recovered associative learning ability but still showed impaired response timing, suggesting lasting cerebellar changes after quitting.
Blocking Cannabinoid Receptors Improved Memory Problems During Morphine Withdrawal in Mice
Blocking cannabinoid receptors improved memory deficits during morphine withdrawal in mice, with chronic treatment being more effective than a single dose.
THC Impaired Spatial Memory but Not Object Memory in Adolescent Monkeys
THC selectively impaired spatial but not object working memory in adolescent monkeys, suggesting less mature brain functions are more vulnerable.
Schizophrenia Patients Who Used Cannabis Actually Had Better Cognitive Function Than Non-Users
Meta-analysis found schizophrenia patients who used cannabis had better cognitive performance than non-using patients, suggesting a different pathway to psychosis.
Heavy Cannabis Users' Brains Lit Up in the Habit Region When Shown Positive Cannabis Associations
Brain imaging showed heavy cannabis users activated habit-related brain regions for positive cannabis associations while non-users activated deliberate control regions.
Students Using "Study Drugs" Actually Had Worse Grades Linked to Cannabis and Alcohol Problems
Study of 984 college students found "study drug" use was linked to escalating cannabis and alcohol problems and declining academic performance, not academic ambition.
Cannabis Impaired Driving-Related Brain Networks Even at Low THC Blood Levels
Brain imaging showed cannabis disrupted attention and executive control networks while increasing self-focused brain activity, even at low blood THC levels.
Schizophrenia Patients Who Used Cannabis Had Better Emotional Memory and More Normal Brain Activity
Schizophrenia patients with cannabis abuse showed better emotional memory and more preserved prefrontal brain activity than non-using patients.
THC's Memory-Damaging Effects Work Through COX-2, and Blocking COX-2 Preserves THC's Medical Benefits
THC impaired memory through COX-2 enzyme induction, and blocking COX-2 eliminated cognitive side effects while preserving THC's Alzheimer's benefits in mice.
Adolescent Cannabis Users Showed Abnormal Risk-Taking and Reward Brain Patterns Even After Quitting
Abstinent adolescents with past cannabis use disorder showed abnormal brain patterns during risk-taking and reward processing that persisted after treatment.
CBD Pretreatment Reduced THC-Induced Paranoia and Memory Impairment in Healthy Volunteers
Pre-treatment with 600 mg CBD reduced THC-induced paranoia (OR=0.22) and eliminated memory impairment (-0.4% vs. -10.6% decline) in healthy volunteers.
Most Cannabis Use Came From People With Recent Mental Illness in a Large U.S. Survey
In a 43,070-person U.S. survey, past-year mental illness was linked to much higher cannabis use and disorder rates, and to most of the cannabis consumed.
Marijuana Use Was Linked to Inattention in Men and Poor Sleep in Women With ADHD
In 76 adults with ADHD, marijuana use correlated with inattention in men and poor sleep quality in women, suggesting sex-specific effects.
Cannabinoid Treatment Reversed MDMA-Induced Memory Deficits but Not Decision-Making Impairment in Rats
Chronic cannabinoid treatment reversed MDMA-induced memory deficits in rats but did not fix impaired effort-based decision making, showing circuit-specific interactions.
Chronic Marijuana Users Showed Reduced Brain Activation During Memory Retrieval in a Virtual Maze
Chronic marijuana users showed impaired spatial memory retrieval and reduced parahippocampal brain activation during a virtual maze task.
ADHD history, not adult cannabis use, drove cognitive deficits in young adults
In young adults, a childhood ADHD diagnosis was linked to executive function deficits, but regular adult cannabis use added no measurable cognitive impairment beyond ADHD alone.
Cannabis use and brain wave changes in people at ultra-high risk for psychosis
Both healthy cannabis users and people at ultra-high risk for psychosis showed reduced P300 brain wave amplitudes, suggesting overlapping effects on information processing.
Both THC and cocaine reduced impulse control accuracy in heavy cannabis users
In heavy cannabis users, both THC and cocaine increased impulse control errors, suggesting acute intoxication with either drug may reduce the ability to resist impulsive decisions.
Adolescent rats were more vulnerable than adults to lasting memory deficits from a cannabinoid
Chronic cannabinoid exposure in adolescent rats caused lasting spatial memory deficits linked to reduced hippocampal neurogenesis, while adult rats were unaffected.
Adolescent cannabis users showed abnormal brain connectivity during impulse control
Adolescent cannabis users showed poorer impulse control and abnormal brain connectivity between parietal and cerebellar regions, a pattern that correlated with recent use.
A specific gene variant determined who lost motor control after THC
A specific AKT1 gene variant determined whether THC impaired psychomotor control, with carriers showing increased errors and reduced brain activation in a motor control region.
ADHD inattention symptoms amplified cannabis-related problems in college students
In 376 college students, inattention symptoms were independently linked to worse cannabis outcomes and strengthened the connection between use level and cannabis-related problems.
Lower Dopamine Production Tracked With Higher Apathy Scores in Regular Cannabis Users
In 14 regular users, lower dopamine synthesis in associative striatum tracked with higher apathy. No control group, and dose measures did not explain apathy.
Brain imaging shows cannabis users work harder to maintain memory performance
Review of brain imaging studies found cannabis users consistently showed increased brain activity during memory tasks, suggesting greater neural effort needed to maintain performance.
Brain scans could identify heavy cannabis users with 84-88% accuracy based on connectivity patterns
Machine learning analysis of brain scans classified heavy cannabis users from controls with 84-88% accuracy based on connectivity patterns spanning cerebellum to prefrontal cortex.
Women Rate Cannabis as More Rewarding Than Men — Even at the Same Dose
Women gave higher "Good" and "Take Again" ratings than men after smoking cannabis in controlled conditions, despite identical intoxication — suggesting sex-specific vulnerability to cannabis's reinforcing effects.
ADHD and autistic traits were each linked to substance use in different ways
In 3,080 twins, both ADHD symptoms and autistic traits independently predicted cannabis use disorders, while autistic traits showed a paradoxical pattern of less alcohol use but higher dependence risk.
Cannabis use worsened attention in adolescents with schizophrenia but not in healthy teens
Cannabis use disorder worsened executive attention in adolescents with schizophrenia but not in healthy teens, with deficits linked to reduced anterior cingulate cortex surface area.
Brain activity before treatment predicted cannabis abstinence during and after therapy
Cannabis-dependent men showed reduced cognitive control brain activity, and those with greater pre-treatment activation in control and reward regions used less cannabis during and after treatment.
Daily Cannabis Users Reported More Hyperactive‑Impulsive ADHD Traits Than Inattentive Ones
Daily cannabis users were more likely to meet hyperactive‑impulsive ADHD symptom criteria; nondaily users showed no subtype split.
Cannabis Use Was Linked to Creativity Only in People Who Were Already Less Creative
Positive schizotypy, not cannabis use, predicted creativity. Cannabis was only associated with divergent thinking in people who scored low on baseline creativity measures.
Activating CB1 Receptors Disrupted Memory-Related Brain Signaling by Altering Protein Production
CB1 receptor activation with a synthetic cannabinoid impaired memory-related brain signaling (LTP) by causing abnormal overproduction of proteins and inhibiting acetylcholine release.
MS Patients Who Used Cannabis Showed More Cognitive Impairment and Altered Brain Activity
MS patients who used cannabis showed worse cognitive performance and more diffuse brain activation on fMRI, suggesting cannabis disrupts compensatory brain mechanisms already strained by MS.
Chronic Cannabis Use Altered Brain Networks Involved in Self-Awareness
Heavy cannabis users showed altered connectivity in self-awareness brain networks, linked to less anxiety but worse memory, that partially persisted after one month of abstinence.
New Data on Sativex for MS Spasticity: No Cognitive Decline and No Driving Impairment
Review of data from 1,000+ MS patients found Sativex did not cause cognitive decline at 12 months, did not impair driving, and maintained effectiveness at lower real-world doses.
THC Disrupted Learning-Related Brain Changes in Adolescent Rats Only When They Were Actively Training
THC disrupted learning-related hippocampal plasticity and neurogenesis markers in adolescent rats, but only during active training, with no effects in untrained animals.
Genetic Vulnerability Plus Juvenile Cannabis Exposure Caused Lasting Cognitive Damage in Mice
Mice with a genetic variant in neural cell adhesion showed delayed but lasting cognitive damage from juvenile THC exposure, while normal mice did not, supporting a gene-environment interaction.
Adolescent Monkeys Given THC for 6 Months Showed Lasting Spatial Memory Impairment
Adolescent monkeys given THC for 6 months showed persistent impairment in spatial working memory (still maturing) but not object working memory (already mature).
Cannabis use and depression predicted which young Swiss men became unemployed and out of school
In nearly 5,000 young Swiss men, cannabis use and depression predicted later disengagement from work and school, but being disengaged did not predict later substance use.
Adolescent THC exposure combined with a schizophrenia-linked gene mutation worsened emotional memory in adult mice
Mice with a schizophrenia-linked gene mutation showed worsened emotional memory and reduced brain activity when exposed to THC during adolescence, demonstrating gene-environment interaction.
Brain scans predicted with 100% accuracy when daily cannabis smokers chose to buy cannabis
Brain scans of 17 daily cannabis smokers identified a neural signature that distinguished decisions to purchase cannabis from decisions to decline with 100% accuracy.
How the endocannabinoid system is involved in Alzheimer's disease and could be a treatment target
Review of endocannabinoid system involvement in Alzheimer's disease found it modulates multiple pathological pathways, suggesting potential as a multi-target therapeutic approach.
THC impaired the brain's ability to stop unwanted responses, and the impairment correlated with psychotic symptoms
In 36 healthy men, THC impaired response inhibition and reduced left inferior frontal brain activation, with both effects correlating with transient psychotic symptoms.
Psychiatric symptoms improved significantly within 16 days of inpatient cannabis detoxification
In 35 cannabis-dependent patients, psychiatric symptoms improved with effect sizes of 0.7-1.4 within 16 days of inpatient detox, though patients self-reported more distress than clinicians observed.
Where CB1 receptors are located in the brain determines how cannabinoids affect memory and appetite
Review showed CB1 receptors produce different effects depending on whether they are on glutamate neurons, GABA neurons, astrocytes, or mitochondria, with implications for targeted therapy.
CBD increased survival and protected brain function in mice with cerebral malaria
CBD treatment increased survival, prevented memory deficits, and reduced brain inflammation in mice with cerebral malaria by lowering cytokines and increasing BDNF.
Chronic cannabis users had reduced brain activity when learning from mistakes and corrected fewer errors
Brain scans of 15 chronic cannabis users showed reduced activation in error-monitoring and memory regions during a learning task, with lower error-correction rates than controls.
Earlier cannabis use was linked to worse memory in young women but not men
Among 69 young cannabis users, earlier initiation was linked to worse episodic memory in females but not males, after controlling for lifetime use, suggesting sex-specific vulnerabilities.
Occasional cannabis smokers showed more psychomotor impairment than frequent smokers after the same dose
After smoking identical cannabis, occasional users showed significantly more psychomotor impairment than frequent users, demonstrating tolerance to performance-impairing effects.
Cannabis may further impair thinking speed and memory in people with MS who already have cognitive problems
Review found preliminary evidence that smoked cannabis may worsen processing speed and memory in MS patients, who already face cognitive challenges from the disease itself.
A 35-year New Zealand study found regular cannabis use linked to lower education, welfare dependence, and psychotic symptoms
35-year birth cohort study of 1,265 New Zealanders found regular cannabis use associated with lower education, unemployment, and psychotic symptoms, but many regular users experienced no harm.
Combined marijuana and nicotine use showed an unusual pattern: smaller hippocampus linked to better memory
Marijuana users had smaller hippocampal volumes, and combined marijuana-nicotine users showed an unusual inverted pattern where smaller hippocampus correlated with better memory.
Intravenous THC caused paranoia in vulnerable individuals by increasing negative emotions and unusual experiences
In 121 paranoia-prone individuals, intravenous THC increased paranoid thoughts through heightened negative emotions and anomalous experiences, not through cognitive impairment.
French medical students who used cannabis were far more likely to fail their exams
Survey of 255 French medical students found cannabis users failed exams at 89% vs. 39% for non-users, with 10% of all students reporting suicidal ideation.
The relationship between cannabis use and exercise is almost entirely unstudied
Commentary found almost no research on the cannabis-exercise relationship, despite widespread beliefs about both motivational impairment and performance enhancement.
Acute cannabinoid use impairs habit memory, but chronic use may strengthen it, potentially fueling addiction
Review found acute cannabinoid use impairs habit-based learning while chronic use enhances it, suggesting a novel habit-memory mechanism for cannabis addiction.
A review for pediatricians on medical marijuana found limited evidence and significant brain development concerns for children
Review for pediatricians found limited evidence for medical cannabis in developmental conditions and well-documented risks to the developing adolescent brain from regular cannabis use.
Heavy marijuana use during adolescence predicted worse emotional functioning in the early 20s, with brain changes mediating the link
Heavy adolescent marijuana users showed disrupted emotional development (no improvement in negative emotionality or resilience), with brain activation differences mediating the outcomes.
Room ventilation dramatically reduced secondhand cannabis smoke effects on cognition, mood, and drug test results
Ventilation at 11 air changes per hour eliminated all measurable secondhand cannabis effects (drug tests, sedation, cognitive impairment) that occurred under unventilated sealed-room conditions.
CBD improved emotional face recognition while THC impaired it, and combining them neutralized the impairment
In a 4-way crossover study of 48 cannabis users, CBD improved and THC impaired emotional face recognition, with their combination preventing impairment.
What Happens When You Combine ADHD Medication with THC
Controlled study of 16 adults found combining THC with methylphenidate produced additive heart rate increases and unique subjective effects, while THC impaired attention that MPH partially offset.
High-Dose Cannabis Disrupts the Brain's Error Detection System
EEG study found high-dose THC disrupted automatic error detection in frequent cannabis users, while even low doses impaired conscious error recognition.
High-Potency Cannabis Actually Impairs Creative Thinking
Controlled study found high-potency cannabis significantly impaired divergent thinking in regular users, while low-potency cannabis had no effect on creativity measures.
Young Adult Cannabis Users Show Thinner Cortex and Smaller Thalamus
MRI study found young adult cannabis users had thinner cortex in the fusiform gyrus and smaller thalamic volumes linked to greater impulsivity compared to matched non-users.
First-Grade Behavior Problems Predict Marijuana Use Transitions in African American Teens
First-grade attention problems predicted marijuana use by seventh grade in African American youth, while externalizing behavior predicted drug exposure opportunities during the high school transition.
MS Patients Who Smoke Cannabis Show More Widespread Brain Volume Loss and Cognitive Impairment
MS patients who smoked cannabis had more widespread cognitive deficits linked to brain volume loss in the thalamus, basal ganglia, and prefrontal regions compared to non-using MS patients.
Past Cannabis Use Linked to Different Hippocampal Shape Changes in Healthy People vs. Schizophrenia
MRI study found past cannabis use was linked to distinct hippocampal shape changes in healthy people (correlated with memory problems) vs. schizophrenia patients (correlated with use duration).
Cannabis Users Show Disrupted Dopamine Receptor Balance in Key Brain Reward Areas
Brain imaging revealed that heavy cannabis users lacked the balanced dopamine receptor signaling between striatal regions that healthy controls displayed during a reaction-time task.
Cannabinoid Treatment During Late Adolescence Reversed the Cognitive Damage From Early Life Stress in Rats
Cannabinoid treatment during late adolescence reversed cognitive deficits and reduced anxiety caused by early life stress in rats, with sex-specific differences in brain receptor changes.
What Clinicians Need to Know About Adolescents and Cannabis
A clinical review examined the evidence on adolescent cannabis use in the context of expanding legalization, covering risks, legal frameworks, and clinical considerations.
Cannabis Benefits and Risks: What a Meta-Analysis Found
A clinical review found cannabinoids offer modest benefits for nausea and inconsistent benefits for pain, while risks include cognitive impairment, driving accidents, dependence, and psychosis.
Synthetic Cannabinoid JWH-018 and Its Variants Impaired Memory More Potently Than THC in Mice
Synthetic cannabinoid JWH-018 and two halogenated variants impaired memory in mice more potently than THC, disrupting hippocampal synaptic transmission through CB1 receptors.
What Research Shows About How Cannabis Affects Driving Ability
Cannabis impairs driving by increasing lane weaving and following distance, with cognitive deficits lasting weeks after cessation and combined alcohol-cannabis use worsening impairment.
What Brain Imaging Reveals About Marijuana's Effects on the Developing Brain
A neuroimaging review found marijuana use is associated with brain structure and function changes, with adolescent-onset use showing the most concerning patterns of alteration.
ADHD Patients in Drug Rehab Started Using Cannabis and Cocaine Earlier and Had More Severe Use Patterns
Among 80 rehab patients, those with ADHD started using substances earlier, and earlier cannabis onset in ADHD patients predicted more severe later cannabis and cocaine use.
Cannabinoids for MS Spasticity and Pain: What the Clinical Trials Show
Randomized trials provide Class 1-2 evidence for cannabinoids treating MS spasticity and pain, but cognitive side effects are a particular concern in this already-impaired population.
ADHD in Young Men Was Linked to Earlier Drug Use, Riskier Patterns, and More Substance Disorders
Among 5,677 young Swiss men, ADHD was independently associated with earlier drug initiation, riskier use patterns, and more substance disorders, even after controlling for antisocial personality.
Combining a Cannabinoid with MDMA Reverses Memory Impairment in Rats Through a Specific Brain Mechanism
Rat study found that MDMA reversed memory impairment caused by a synthetic cannabinoid in the hippocampus through an NMDA receptor-dependent mechanism, potentially explaining why some people combine these substances.
Young Cannabis Users Show Different Brain Activation Patterns When Making Decisions Under Social Pressure
Brain scans revealed that young cannabis users showed unique reward-region activation when following social pressure to conform, with the strength of this activation correlating with how much cannabis they used.
Cannabis Users Show Greater Brain Response to Peer Information and More Effort When Disagreeing with Peers
Cannabis-using young adults showed greater brain activation in the caudate when receiving peer information and took longer to make decisions opposing the group, suggesting heightened neural sensitivity to social influence.
The Body's Own Cannabis-Like Chemical Causes Fewer Cognitive Problems Than THC in Monkeys
Primate study showed THC impaired multiple cognitive functions while the body's own cannabinoid anandamide and drugs that boost it had minimal cognitive effects, suggesting a path to safer cannabinoid medicines.
How Cannabis and Other Drugs Hijack the Brain's Learning and Memory System to Drive Addiction
Review reveals cannabis may enhance hippocampal learning during use (strengthening drug-context memories) while impairing it during withdrawal (driving relapse), creating a cycle that maintains addiction.
First Rigorous Study Confirms THC Causes Temporary Amotivation, But Cannabis Dependence Does Not Reduce Overall Motivation
First rigorous study shows THC acutely reduces motivation temporarily, while cannabis dependence is associated with impaired reward learning but preserved overall motivation when sober.
Cannabis Use Thins the Brain's Frontal Cortex in Young Adults, With Distinct Effects in Those With ADHD
MRI study found cannabis use was associated with thinner frontal cortex in young adults, with distinct brain structure patterns emerging in cannabis users who also had persistent ADHD.
Systematic Review Finds Altered Brain Function in Adolescent Cannabis Users Despite Normal Task Performance
Systematic review of 13 brain imaging studies found adolescent cannabis users showed altered frontal-parietal brain function during cognitive tasks while maintaining normal performance, suggesting compensatory mechanisms.
First Controlled Study Comparing Cannabis Effects in Teens vs Adults Reveals Surprising Vulnerability and Resilience Patterns
First controlled comparison found adolescents felt less stoned and had fewer memory problems from cannabis than adults, but showed impaired impulse control and no feeling of having had enough, potentially driving escalated use.
Cannabis Use and ADHD Both Linked to Thinner Brain Cortex, But Through Different Mechanisms
Persistent ADHD and frequent cannabis use each independently associated with thinner cortex in a key impulse control brain region in young adults.
ADHD Medication Helped People With ADHD and Cocaine Dependence Use Less Marijuana
ADHD medication (mixed amphetamine salts) was associated with more marijuana-free weeks in people with co-occurring ADHD and cocaine dependence.
Cannabis and Cocaine Reduced Impulse Control and Brain Connectivity, But Only in People With Certain Genetics
Controlled trial shows cannabis and cocaine increase impulsivity and reduce brain connectivity, but only in people with a genetic variant predisposing to higher dopamine levels.
ADHD Reduced Brain Activity for Impulse Control Regardless of Cannabis Use
fMRI study finds ADHD reduced impulse control brain activation regardless of cannabis use, while cannabis-using controls recruited compensatory brain regions that ADHD participants could not.
Long-Term Cannabis Use Affected Attention Differently in People With and Without Schizophrenia
Chronic cannabis use reduced attention-related brainwave responses in healthy people but not in those with schizophrenia, suggesting pre-existing endocannabinoid differences in schizophrenia.
Sativex Did Not Impair Cognitive Function in MS Patients Over 6 Months
40 cannabis-naive MS patients showed no significant cognitive or behavioral decline after 6 months of Sativex treatment for spasticity.
Prenatal Marijuana Exposure Was Linked to Altered Brain Activity in Young Adults 18-22 Years Later
Young adults prenatally exposed to marijuana showed altered brain activation (increased left posterior activity) during executive function tasks despite normal performance, suggesting neural compensation 18-22 years after exposure.
Cannabis and Cocaine Had Opposite Acute Effects on Impulse Control and Brain Activity
Controlled crossover study finds cocaine enhanced and cannabis impaired impulse control with mirror-image effects on brain electrical activity, both acting on evaluative rather than detection stages of inhibition.
Cannabinoids Impaired Learning But Actually Helped Memory Consolidation in the Cerebellum
Cannabinoids in the cerebellum impaired new learning but enhanced memory consolidation in a specific 1-3 hour window after training, revealing a dual role in memory processing.
ADHD Was a Risk Factor for Starting New Substances, Independent of Conduct Problems
Study of 5,103 Swiss men finds ADHD predicted initiating new substances (especially amphetamines) over 15 months, independent of conduct disorder, without escalating existing substance use.
Comprehensive Brain Imaging Review: How Cannabis Changes Brain Structure and Function
Review of 103 brain imaging studies shows regular cannabis use alters brain structure (hippocampus, amygdala), cognitive function (with compensatory recruitment), dopamine systems, and CB1 receptors.
Heavy Cannabis Users Showed Reduced Brain Activity When Evaluating Emotional Content
fMRI study finds heavy cannabis users show reduced medial prefrontal cortex activity during conscious emotional evaluation of both positive and negative content.
Adolescent THC exposure causes lasting brain changes in male rats, but different from females
Adolescent THC exposure produced lasting memory deficits and psychotic-like behaviors in male rats, driven by glutamate signaling disruption and neuroinflammation specifically in the hippocampus.
Natural brain peptides that act on cannabinoid receptors can both help and hurt memory in mice
Natural brain peptides targeting the CB1 cannabinoid receptor had opposite effects on memory depending on brain health: blocking CB1 helped healthy mice, while activating it restored memory in an Alzheimer's model.
CB1 receptors in the brain's reward center are needed to learn that relief feels good
CB1 receptors in the nucleus accumbens were essential for learning relief associations in rats but not for recalling them, revealing a role for cannabinoid signaling in emotional memory formation.
Chronic cannabis users showed weakened brain connections between motivation centers, but they normalized after a month of abstinence
Chronic cannabis users showed weakened brain connections between motivation centers and both frontal and visual processing areas, but these changes began normalizing after one month of abstinence.
Review of 36 studies confirms cannabis impairs driving skills and doubles or triples crash risk
Review of 36 studies confirms cannabis impairs multiple driving functions and doubles or triples crash risk, with cannabis-alcohol combination increasing injury risk nearly 11-fold.
Hempseed extract improved memory and reduced brain aging markers in rats with accelerated aging
Hemp seed extract improved memory and reduced brain aging markers in rats by boosting antioxidants, reducing inflammation, and decreasing Alzheimer's-related protein changes.
Synthetic cannabinoid users showed significantly worse executive function than both cannabis users and non-users
Synthetic cannabinoid users showed significantly worse executive function, memory, and mental health compared to both recreational cannabis users and non-users across two countries.
First randomized trial of cannabinoids for ADHD found trends toward improvement in hyperactivity and impulsivity
First RCT of cannabinoids (Sativex) for ADHD found trends toward improvement in hyperactivity and impulsivity in 30 adults, but results did not reach significance after multiple testing correction.
Review argues cannabis safety evidence is insufficient to support legalization, highlighting harms to mood, cognition, and driving
Review arguing that cannabis harms mood, cognition, psychiatric health, and driving, and that public perception of low risk is unsupported by the scientific evidence.
Canadian Paediatric Society review linked adolescent cannabis to brain damage, dependence, mental illness, and declining academic performance
Canadian Paediatric Society review documenting that adolescent cannabis use causes brain changes and is associated with dependence, mental illness, cognitive decline, and academic underperformance.
In first-episode psychosis, cigarette smoking was linked to worse cognition and function even after accounting for cannabis use
In 140 first-episode psychosis patients, cigarette smoking was independently linked to worse cognition and functioning after adjusting for cannabis use, with 53% of patients smoking.
Medical marijuana patients showed improved brain function and executive performance after 3 months, opposite to recreational cannabis effects
Medical marijuana patients showed improved executive function and more normal brain activation patterns after 3 months, along with decreased opioid and benzodiazepine use.
Synthetic "Spice" Cannabinoids Disrupted Brain Communication More Potently Than THC
Brain slice study showing JWH-018 was 47 times more potent than THC at disrupting hippocampal synaptic transmission, with all synthetic cannabinoids tested impairing memory-related brain plasticity.
Oral Cannabis Impaired Memory and Damaged Brain Structures in Rats
Rat study showing 7 days of oral cannabis impaired spatial memory, increased anxiety-like behavior, and caused visible neuronal damage in the cortex and hippocampus.
ADHD and Cannabis Have Separate Effects on Brain Connectivity in Young Adults
Brain imaging study of 75 young adults finding that childhood ADHD and current cannabis use affect separate brain networks, with no evidence that cannabis worsens ADHD-related connectivity changes.
Heavy Cannabis Use Did Not Shrink the Hippocampus in Young Adults Over 3 Years
Longitudinal study following 20 heavy cannabis users and 23 controls for 39 months, finding no hippocampal volume differences or divergent growth trajectories, regardless of dose or age of onset.
Cannabis Users Seem More Creative, But It's Actually Their Personality
Study of 721 people finding sober cannabis users appeared more creative, but this was entirely explained by their higher levels of openness to experience rather than any effect of cannabis.
What Happens to Adolescent Brains Exposed to Cannabis? A Comprehensive Review
Comprehensive review finding strong evidence from human and animal studies that adolescent cannabis exposure causes lasting deficits in cognition, emotion, and psychosis risk that do not occur with adult-onset exposure.
Escalating Teen Cannabis Use Was Linked to Altered Brain Reward Circuits and Worse Outcomes at 22
Longitudinal study of 158 young men finding escalating adolescent cannabis use disrupted reward-prefrontal brain connectivity, predicting more depression, anhedonia, and lower education at age 22.
Heavy Cannabis Users Who Develop Schizophrenia Show Better Cognitive Function Than Non-Users
Study of 61 schizophrenia patients finding those with heavy pre-psychosis cannabis use had fewer neurological signs and better cognitive function, suggesting cannabis-associated psychosis may be a distinct disease subtype.
Evidence That Cannabis Damages the Brain, Especially White Matter
Critical review plus fatal case report finding strong evidence that chronic cannabis use damages brain white matter and impairs cognition, with few objective data supporting cannabis over conventional therapies for neurological conditions.
How Cannabis and Alcohol Affect the Developing Adolescent Brain
Review of neuroimaging evidence showing cannabis and alcohol alter adolescent brain development, with most cognitive effects resolving after abstinence but attentional deficits persisting.
Cannabis Edibles Impaired Balance and Walking Tasks in Occasional Users But Not Frequent Users
Controlled study showing oral cannabis caused 6.4x higher impairment odds on sobriety tests in occasional users, with tolerance in frequent users, highlighting the delayed impairment risk of edibles.
Why Recreational Drugs Including Cannabis Damage Well-Being Through the Same Core Mechanism
Review arguing that cannabis and stimulant drugs damage well-being through the same core mechanism: cyclical mood disruptions that chronically stress the body's hormonal and neurological systems.
Verbal Memory Improved in Schizophrenia Patients Who Stopped Using Cannabis for 28 Days
Small prospective study found significant verbal memory improvement (d = 1.07) in schizophrenia patients who achieved 28 days of cannabis abstinence.
Cannabis Has Opposite Effects on Brain Signal Processing in Schizophrenia Patients Versus Healthy People
Study found cannabis had opposite effects on brain signal filtering in schizophrenia (improved) versus healthy people (impaired), suggesting fundamental endocannabinoid system differences.
CBD Disrupted Fear Memory Consolidation in Rats, but Only When Given at a Specific Time Window After Learning
Rat study found CBD disrupted fear memory consolidation when injected into the prefrontal cortex 5 hours (but not immediately) after fear learning, reducing dopamine activity and memory gene expression.
CB1 Cannabinoid Receptors Drive the Memory Problems That Occur During Nicotine Withdrawal
Mouse study found that memory problems during nicotine withdrawal are driven by increased endocannabinoid (2-AG) signaling through CB1 receptors on inhibitory neurons, with associated loss of dendritic spines.
Indian Research on Cannabis and Mental Health Reveals High Rates of Psychosis, But Major Gaps in Understanding Why
Systematic review of 52 Indian studies found high co-occurrence of cannabis and psychotic disorders, but nearly all studies used male-only samples and none adequately explored causation.
CBD Disrupted Both Specific and Generalized Fear Memories Through Cannabinoid Receptors in the Hippocampus
Rat study showing CBD disrupted both specific and generalized fear memory consolidation through anandamide-mediated CB1 and CB2 receptor activation in the dorsal hippocampus.
Cannabis-Dependent People Had Significantly Blunted Dopamine Release in the Brain's Reward System
PET imaging study found severely cannabis-dependent individuals had markedly reduced striatal dopamine release (effect size 1.48), correlating with cognitive deficits and negative symptoms.
Regular cannabis users showed impaired ability to regulate negative emotions in brain scans
Brain imaging showed regular cannabis users had impaired ability to downregulate negative emotions, with disrupted amygdala-prefrontal cortex communication during regulation tasks.
People who started using cannabis as teenagers made worse decisions in a gambling task
Early-onset cannabis users (before age 18) performed worse on a gambling task than late-onset users and non-users, with decision-making driven by short-term gains rather than loss avoidance.
Genetic variations in dopamine genes interacted with early cannabis use to alter hippocampal brain structure
Brain imaging of 59 young men found early cannabis use altered hippocampal subregion volumes, with effects modified by the DAT1 dopamine transporter gene variant.
Brain scans reveal different patterns of altered function in adult versus adolescent cannabis users
Meta-analysis of 20 fMRI studies found cannabis users show altered brain activation patterns, with different changes in adults (temporal/frontal regions) versus adolescents (parietal/putamen).
Young psychosis patients who use cannabis have worse cognitive function than non-using patients
Meta-analysis of 14 studies found young psychosis patients who currently use cannabis perform worse on IQ, verbal learning, and working memory, except for set-shifting where they excelled.
People with ADHD were three times more likely to use cannabis, and hyperactive types started youngest
Adults with ADHD used cannabis at 3x the rate of those without, with the hyperactive subtype starting at age 13.8 versus 16.3 for inattentive, and 4x higher personality disorder rates.
Nearly half of young multiple sclerosis patients used marijuana, most for symptom relief despite recognizing memory effects
Survey of 52 young MS patients found 48% used marijuana for relaxation and symptoms, with 64% of users acknowledging negative memory and focus effects.
THC impairs short-term memory through a specific protein signaling pathway in the hippocampus
THC impairs short-term memory through hippocampal PKC signaling and long-term memory through a separate mTOR pathway, with PKC blockers fully preventing the short-term memory deficit.
Low-Dose THC Improved Memory in Aging Mice. Higher Doses Impaired It in Young Ones.
THC impairs cognition in young brains but animal research shows very low doses may restore memory and protect against neurodegeneration in aging brains — a biphasic dose-response.
Cannabis withdrawal symptoms in adults with ADHD looked similar to those in people without ADHD
Among 23 cannabis-dependent adults with ADHD, 96% had withdrawal symptoms similar to non-ADHD populations, with money being the top motivation (87%) to quit.
Even modest previous cannabis use blunted THC's effects on psychosis symptoms and brain function
THC challenge study found modest prior cannabis users had worse baseline cognition but were protected from THC's psychotic effects, showing tolerance from even limited exposure.
Your genes may determine how much cannabis affects your thinking and memory
Review of 13 studies found that COMT and other dopamine-related gene variants modulate how cannabis impairs working memory, attention, and other cognitive functions.
Overview of psychiatric effects of cannabinoids from acute use to chronic exposure and withdrawal
Overview found cannabinoids produce dose-dependent acute effects on anxiety, mood, and cognition, with chronic use linked to tolerance, dependence, withdrawal, and associations with psychiatric disorders.
Childhood ADHD predicted earlier marijuana use, but twin analysis suggests shared genetics rather than a causal link
Twin study of 3,762 adolescents found childhood ADHD predicted earlier marijuana use, but identical twin analysis indicated shared genetics, not ADHD itself, primarily drive the link.
THC exposure dampened human neuron gene activity in ways resembling patterns seen in schizophrenia
THC exposure dampened human neuron gene responses to stimulation, with changes in synaptic and glutamate pathways overlapping schizophrenia, autism, and intellectual disability gene patterns.
Cannabis use showed limited brain structural changes in schizophrenia and bipolar patients, except for those who started before illness onset
MRI study of 314 schizophrenia/bipolar patients found cannabis use associated with limited brain structural changes, except for cortical thinning in frontal regions among those who started using before illness onset.
Adolescent brain surface area changes after starting alcohol and cannabis differed from alcohol-only users
Longitudinal study of 69 youth found alcohol-only users showed greater brain surface area decreases in the orbitofrontal cortex than those who used both alcohol and cannabis.
Chronic THC impaired working memory in monkeys but did not change dopamine D2/D3 receptor levels
Rhesus monkeys given daily THC for 12 weeks showed persistent working memory deficits (but not other cognitive domains) that recovered within 2 weeks of stopping. Dopamine D2/D3 receptors were unaffected.
Brain volume loss in polysubstance users was linked to total number of substances, not cannabis specifically
Study of 169 men found brain volume loss in the prefrontal cortex was linked to total number of substances used, not any single drug. Cannabis showed no independent effect after controlling for polysubstance use.
Chronic synthetic cannabinoid users showed reduced brain volume and impaired working memory neural activity
First neuroimaging study of synthetic cannabinoid users found reduced gray matter volume across multiple brain regions and impaired neural activity during working memory tasks.
Cannabis use disorder altered brain connectivity between prefrontal cortex and striatum during working memory tasks
fMRI study found cannabis use disorder participants showed altered prefrontal-striatal brain connectivity during working memory, with compensatory increases in some pathways offsetting decreases in others.
Cannabis users with high distress intolerance showed enhanced rather than impaired brain conflict-monitoring under stress
EEG study found cannabis users with high distress intolerance showed enhanced brain conflict-monitoring under stress, which was linked to fewer cannabis problems, challenging the stress-impairment model of addiction.
Adults with ADHD who persistently used substances perceived cannabis as therapeutic for mood and ADHD symptoms
MTA follow-up found adults with ADHD who persistently used substances perceived cannabis as improving both mood and ADHD symptoms, though broad substance-mood perceptions did not differ from non-ADHD users.
CBD did not block THC-induced psychotic symptoms or memory impairment when both were vaporized at a 2:1 ratio
Randomized crossover trial found vaporized CBD at 2:1 ratio did not block THC-induced psychotic symptoms or memory impairment. CBD alone helped only light users, not frequent users.
Cannabis use disorder in ADHD adolescents increased hospital costs, length of stay, and alcohol abuse risk while reducing treatment utilization
ADHD adolescents with cannabis use disorder had higher hospital costs, longer stays, and 17-fold higher alcohol abuse risk, but received 55% less psychiatric medication and 59% less behavioral therapy.
Adolescent THC Exposure Changed Gene Activity in Rat Brains Through Epigenetic Modifications
THC during adolescence caused epigenetic changes in rat brains that altered gene activity and led to cognitive deficits - effects not seen with adult exposure. Blocking the changes prevented cognitive harm.
Cannabis and Alcohol History Did Not Make Brain Shrinkage Worse in Schizophrenia Patients
Brain imaging found that schizophrenia-related gray matter reductions were the same whether patients had a history of cannabis/alcohol use or not.
Cannabis Cognitive Effects Are Small and Largely Disappear After 72 Hours of Abstinence
Meta-analysis of 69 studies found cannabis cognitive deficits are small (d=-0.25) and become non-significant after 72 hours of abstinence — meaning most impairment is residual drug effect, not lasting damage.
THC Disrupted the Brain's Ability to Filter Sensory Information in Both Humans and Rats
Translational study in humans and rats showed THC disrupts sensory gating through CB1 receptors by altering theta-band brain oscillations, with CBD failing to prevent these effects.
Earlier Cannabis Use Was Linked to Slower Reaction Times in Adulthood Through Brain Encoding Changes
Adults who started cannabis earlier had slower reaction times at 28 due to reduced brain encoding activation, but the same pattern appeared after single use, suggesting pre-existing differences rather than drug-caused damage.
Brain Differences Linked to Cannabis Use Actually Existed Before Teens Ever Tried Cannabis
Prospective brain imaging found that neurocognitive differences attributed to early cannabis use actually existed at age 12, before any cannabis use began, supporting a pre-existing risk model.
Too Little Research to Know How Cannabis Affects Athletic Performance
Systematic review found only three trials on marijuana and athletic performance, with low-quality evidence for both potential benefits (bronchodilation) and harms (decreased work capacity).
Cannabis Actually Normalized Brain Network Connectivity in Schizophrenia Patients
Pilot fMRI found schizophrenia patients had abnormal brain network connectivity that actually normalized after cannabinoid administration, correlating with improved working memory performance.
Brain Imaging Meta-Analysis Found Cannabis Users Have Reduced Cognitive Control and Increased Reward Activity
Neuroimaging meta-analysis found cannabis users consistently show decreased activation in cognitive control regions (ACC, DLPFC) and increased activation in reward regions (striatum).
Brain Changes in Marijuana Users Persisted After 28 Days Without Using
Brain imaging found altered emotional processing circuits in marijuana users that persisted after 28+ days of abstinence, specifically during negative emotions, potentially explaining vulnerability to relapse.
Adolescent THC Exposure Delayed Learning Ability in Adult Rats, but Effects Faded Over Time
Rats given escalating THC during adolescence showed learning delays and sensorimotor gating impairments as adults, but both deficits appeared to diminish over time, suggesting partial neural recovery.
CBD helped songbirds recover their learned songs faster after brain injury
CBD helped zebra finches recover their learned songs faster after targeted brain lesions, with higher doses reducing both the severity and duration of vocal impairment.
Adding CBD to cannabis did not reduce THC-related driving and cognitive impairment
A controlled trial found cannabis with equal CBD and THC impaired driving and cognition as much as THC-only cannabis, with CBD actually worsening some cognitive tasks, possibly by increasing THC blood levels.
A comprehensive profile of THC: from ancient medicine to modern controversy
A comprehensive review of THC covers its pharmacology as a CB1 partial agonist, approved uses for pain and nausea, and ongoing debates about psychosis risk, cognitive effects, and addiction potential in 192 million users worldwide.
Teen cannabis use disorder was linked to dulled brain responses to threatening situations
An fMRI study found adolescent cannabis use disorder was linked to reduced brain activation in threat-processing regions including the amygdala, an effect not seen with alcohol use disorder.
Brain function changes from cannabis use persisted in teens even after a month of abstinence
A meta-analysis found altered brain network function in teen cannabis users even after 25+ days of abstinence, when cognitive test performance had already recovered.
Chronic cannabis use consistently alters cerebellum structure and function, affecting memory and decision-making
A review of 40 studies found chronic cannabis use consistently increases cerebellar gray matter volume, alters resting brain activity, and impairs memory and decision-making.
A comprehensive review of human brain imaging reveals how cannabis affects executive function, emotion, memory, and reward
A comprehensive neuroimaging review found cannabis affects executive, emotional, reward, and memory brain systems through direct and indirect pathways, with adolescent use carrying particular risk for lasting changes.
Young psychosis patients who used cannabis showed no cognitive advantage or disadvantage over non-users
Among young adults with psychosis, cannabis users and non-users showed no cognitive differences at illness onset, suggesting cannabis may trigger psychosis in individuals who would not otherwise develop it.
THC boosted brain activity in attention networks, and a common gene variant influenced the effect
THC increased brain activity in attention and salience networks, with the COMT gene variant determining how executive networks responded, linking dopamine genetics to cannabis susceptibility.
Prenatal cannabinoid exposure altered early motor development in rats and worsened alcohol-related motor impairment in females
Prenatal cannabinoid exposure in rats accelerated early motor development but worsened alcohol-related motor impairment specifically in females, with combined exposure showing complex interactions.
Adolescent cannabis or THC exposure in rats did not produce lasting anxiety, depression, or cognitive effects in adulthood
Adolescent cannabis smoke and THC exposure in rats produced no lasting anxiety, depression, or cognitive effects in adulthood, suggesting human associations may involve non-cannabinoid factors.
Decades of research show cannabis affects brain structure and cognition, raising questions for medical use
A review found substantial evidence that cannabis affects brain structure and cognition, particularly during adolescence, while paradoxically some cannabinoid compounds are approved for medical use in children.
Heavy cannabis use led to Wernicke's encephalopathy, a brain condition usually seen with alcoholism
A heavy cannabis user developed Wernicke's encephalopathy (brain damage from thiamine deficiency) after severe vomiting from cannabis hyperemesis, a complication usually associated with alcoholism.
THC blood levels do not reliably predict driving impairment, creating a policy challenge
A review of 52+ studies found cannabis impairs driving but blood THC levels do not reliably predict impairment, creating a fundamental challenge for per se driving laws.
Only cannabis-dependent users, not regular users, showed smaller hippocampi in a large multi-site study
A large multi-site study found only cannabis-dependent users, not regular non-dependent users, showed smaller hippocampi, regardless of dose, suggesting dependence involves unique brain changes.
Cannabis carries both real risks and real therapeutic potential, but causal evidence is still largely missing
A balanced review found cannabis is associated with multiple health harms but causal evidence is largely missing, while cannabinoid-based drugs show legitimate therapeutic potential across many conditions.
Cannabis modulates six major brain neurotransmitter systems, with profound implications for mental health
A review found cannabinoid receptors modulate dopamine, serotonin, noradrenaline, GABA, glutamate, and opioid systems, explaining the broad spectrum of cannabis effects on mental health.
Adolescent synthetic cannabinoid users showed thinner brain cortex, especially those with ADHD
Adolescent synthetic cannabinoid users had thinner frontal cortex than controls, with ADHD comorbidity producing additional brain changes, suggesting interactive effects on the developing brain.
Cannabis-using youth showed weaker brain circuit activation when trying to resolve mental conflicts
Cannabis-using youth showed weaker frontostriatal brain circuit activation during cognitive conflict tasks, suggesting self-regulation circuit changes appear early in the course of cannabis use.
First genome-wide significant gene identified for cannabis use disorder risk
Genome-wide study of over 350,000 people identifies CHRNA2, a nicotinic receptor gene, as the first replicated genetic risk factor for cannabis use disorder, linking it to cholinergic and cognitive pathways.
Daily High-Potency Cannabis Use and Psychosis Risk: The Largest European Study Drew a Direct Line
Across 11 European cities, daily high-potency cannabis use was linked to ~5x higher odds of first-episode psychosis, with population impact varying by local market potency.
Young men with ADHD are more likely to develop persistent problematic substance use patterns
Longitudinal study of 4,975 young men found ADHD predicted persistent risky alcohol and nicotine use but was associated with maturing out of risky cannabis use over 15 months.
Female Rats' Brains Responded More Strongly to Repeated THC Than Males' — Hormones Were Part of the Story
Female rats showed greater CB1 receptor changes than males after identical THC exposure across all brain regions. Estradiol contributed to the difference.
MS patients who quit cannabis for 28 days showed significant cognitive improvement on every test
Controlled study of 40 MS patients found 28 days of cannabis abstinence produced significant improvements in every cognitive measure tested, with corresponding increases in brain activation on fMRI.
Adolescent cannabis users may have more cognitive problems than adult users, but the picture is complex
Systematic review comparing adolescent and adult cannabis users suggests teens may be more vulnerable to executive function deficits, especially heavy users, but these effects may reverse with sustained abstinence.
Finnish adult ADHD patient found medical cannabis more helpful than Ritalin over five years
Five-year case report of Finnish adult ADHD patient who found medical cannabis (THC-dominant plus THC/CBD blend) more effective than Ritalin for emotional regulation, anger, and concentration.
Synthetic cannabinoid 5F-AMB reduced anxiety and impaired memory in mice through CB1 receptors
Mouse study maps synthetic cannabinoid 5F-AMB's effects: anxiety reduction and memory impairment via CB1 receptors in different brain regions, with severe locomotor impairment at systemic doses.
Adolescent cannabinoid exposure left lasting marks on reward processing in the adult prefrontal cortex of rats
Rat study shows adolescent cannabinoid exposure produces lasting reductions in prefrontal cortex activity during reward processing in adulthood, suggesting disrupted brain maturation.
Recency and frequency of teen cannabis use matter most for brain health, but preexisting differences also play a role
Prospective neuroimaging studies find recency, frequency, and age of onset of teen cannabis use predict brain health outcomes, with preexisting brain differences also contributing to vulnerability.
Why only some teens develop cognitive problems from cannabis: a genetic vulnerability in brain support cells
Mouse study shows adolescent THC only caused lasting memory impairment when combined with genetic vulnerability in astrocytes (support cells), operating through an inflammatory pathway blockable by a COX-2 inhibitor.
Cannabinoid exposure can cause lasting cognitive and psychiatric problems, especially in adolescents
Review of multiple evidence types consistently links cannabinoid exposure to persistent cognitive deficits and psychosis risk, with adolescence as a critical vulnerability window.
Endocannabinoid enzyme inhibitors had mixed effects on schizophrenia-like symptoms in mice
Low-dose FAAH inhibition improved memory in a mouse schizophrenia model, but higher doses of both FAAH and MAGL inhibitors worsened cognitive and behavioral symptoms.
Fathers' THC exposure before conception caused lasting attention problems in rat offspring
Paternal THC exposure in rats (modest dose, 12 days) caused long-lasting attention impairments in offspring, likely through epigenetic changes in sperm.
Synthetic cannabinoid JWH-018 impairs memory by raising brain endocannabinoid levels and lowering BDNF
JWH-018 impaired memory by elevating brain endocannabinoids (suppressing FAAH and MAGL) and reducing BDNF, with all effects reversible by CB1 receptor blockade.
Meta-analysis confirms regular cannabis users have smaller hippocampus and orbitofrontal cortex
Meta-analysis of 30 neuroimaging studies found regular cannabis users have significantly smaller hippocampus and orbitofrontal cortex volumes.
THC disrupted brain connectivity by boosting striatal glutamate and dopamine in occasional users
Human neuroimaging study shows THC increases striatal glutamate and disrupts brain connectivity, with these changes predicting subjective high and attention deficits.
HIV and regular marijuana use together produced greater brain activation changes than either alone
fMRI study found combined HIV and regular marijuana use produced synergistic brain activation changes in the fronto-insular cortex during cognitive tasks.
Prospective study finds no link between adolescent cannabis use and adult brain structure
Prospective study following boys from age 13 to their 30s found no association between adolescent cannabis use patterns and adult brain structure in 14 regions.
Marijuana use in adolescents altered BDNF levels, with onset age influencing the magnitude of change
Longitudinal study of 500 adolescents found marijuana use caused BDNF alterations (not vice versa), with age of onset influencing the pattern of neurotrophin changes.
Vaporized THC and sleep in rats: only a 1-hour NREM bump at top dose
Rats showed more NREM sleep only for 1 hour after the highest vaporized THC dose, only in the light phase.
Population study of 3,826 teenagers found cannabis, more than alcohol, caused lasting cognitive deficits
Population study of 3,826 adolescents found cannabis caused lasting cognitive deficits in inhibitory control and working memory, with effects independent of and more pronounced than alcohol.
Adenosine A2A receptor blockers reversed chronic cannabinoid-induced memory deficits in rats
Chronic A2A receptor antagonism (istradefylline) reversed cannabinoid-induced memory deficits and partially rescued hippocampal synaptic plasticity in rats.
CBD did not prevent THC's cognitive impairment or withdrawal in mice, but showed anxiolytic effects alone
Mouse study found CBD did not prevent THC cognitive impairment or withdrawal, but CBD alone showed anxiolytic effects without cognitive harm or dependence.
A single hit of vaporized THC suppressed brain gamma waves in rats for at least a week
A single session of vaporized THC suppressed gamma-frequency brain activity in multiple rat brain regions, and most effects were still present a week later.
Adding cannabis to cocaine use made cognitive problems worse, not better
Cocaine users who also used cannabis heavily had worse cognitive performance and no reduction in relapse compared to cocaine-only users.
THC in urine linked to worse working memory and altered brain activity in a large study
In over 1,000 people, testing positive for THC was linked to worse working memory and altered brain activity, but past cannabis use history was not.
Researchers tried to build a phone-based THC impairment test and it mostly didn't work
THC impaired standard cognitive tests but brief phone-based equivalents mostly failed to detect the impairment, casting doubt on phone apps as cannabis sobriety tests.
Marijuana and depression together have additive negative effects on verbal memory and brain structure
Young adults with both marijuana use and depression had worse verbal memory and thinner cortex than those with either condition alone, suggesting additive harm.
Your COMT gene variant determines how much THC impairs your working memory
COMT Val/Val carriers were most vulnerable to THC-induced cognitive deficits. A COMT inhibitor reduced these effects, but THC's psychosis-like effects were independent of dopamine.
A cannabinoid receptor gene variant predicts cognitive improvement in first-episode psychosis treatment
A cannabinoid receptor gene variant (CNR1 rs7766029) predicted cognitive improvement over 18 months in first-episode psychosis patients.
Schizophrenia patients who used cannabis showed better brain processing than those who did not
Schizophrenia patients who used cannabis showed better auditory processing (MMN) than non-using patients, possibly reflecting a less impaired subgroup.
People with cannabis use disorder have an automatic attentional pull toward cannabis-related images
Cannabis users showed involuntary attentional capture by cannabis cues within 125-200 ms, along with more errors and poorer selective attention.
Ultra-Low THC Doses Protected Mouse Brains From Injury. Regular Doses Did the Opposite.
Mouse studies showed THC at doses thousands of times below the psychoactive threshold protected against brain injury and cognitive decline, while standard doses impaired cognition.
Cannabis use frequency, cognitive self-perception, and anxiety are the strongest predictors of use disorder severity in young adults
In young adult regular cannabis users, the strongest predictors of use disorder severity were use frequency, beliefs about cannabis impairing cognition, perceived cognitive deficits, and anxiety.
In Rats, Low-Dose THC Felt Rewarding Through CB1 Receptors. Higher Doses Felt Aversive Through CB2.
Rat study found THC enhances brain reward at low doses (CB1) but suppresses it at high doses (CB2) — a biological explanation for why more weed doesn't mean more fun.
Testing an Alzheimer's drug to counteract cognitive effects of cannabis use
Pilot trial found galantamine was safe in cannabis use disorder but showed no cognitive benefits beyond placebo over 10 days.
Synthetic cannabinoid JWH-018 impairs cognition and triggers dissociation in some users
Controlled study found the synthetic cannabinoid JWH-018 impaired memory and tracking in all users, with dissociation and amnesia in those who got the strongest high.
Higher aerobic fitness may protect against cognitive effects of cannabis use
Study of 79 young adults found aerobic fitness moderated cognitive deficits associated with cannabis use, with fitter users performing better after 3 weeks of abstinence.
Attention problems in young cannabis users are from cannabis, not subclinical ADHD
Study of 72 young people found cannabis use predicted slower attention, and subclinical ADHD symptoms did not explain this deficit.
Cannabinoid receptor activation impairs fear extinction in adolescent rats but improves it in adults
A cannabinoid agonist that improved fear extinction in adult rats impaired it in adolescent and juvenile rats, with younger animals showing higher CB1 receptor levels in brain regions tied to fear processing.
Narrative review explores whether the adolescent brain is more vulnerable to cannabis effects
A narrative review found consistent evidence linking adolescent cannabis use to alterations in brain structure, function, and connectivity, with some changes appearing to persist into adulthood.
Systematic review finds cannabis users show altered brain activation during memory tasks
A systematic review of 12 neuroimaging studies found cannabis users show altered brain activation during memory tasks, with verbal memory particularly affected and some evidence suggesting a causal role for cannabis.
Single dose of CBD increased blood flow to the hippocampus in healthy adults
A small crossover trial found that 600mg of CBD increased blood flow to the hippocampus by an average of 15 mL/100g/min, with increased orbitofrontal blood flow correlating with faster working memory reaction times.
Prenatal THC exposure in rats led to impaired emotional memory and increased alcohol-seeking in adolescent offspring
Adolescent rat offspring exposed to THC during fetal development showed impaired emotional memory, reduced neuropeptide Y neurons, and increased alcohol-seeking behavior, suggesting prenatal THC may create lasting vulnerability.
EEG brain patterns during simulated driving correlated with cannabis-impaired lane-keeping
A small crossover trial found cannabis-intoxicated drivers showed decreased theta brain waves that correlated with worse lane-keeping in a simulator, suggesting EEG patterns could help identify cannabis impairment.
Mobile phone cognitive tests detected slight impairment from marijuana in young adults' daily lives
A 30-day mobile monitoring study of 60 young adults found slight but significant cognitive slowing and accuracy decreases on phone-based tasks when participants reported being high from marijuana.
Review of 63 neuroimaging studies finds adolescent cannabis users show brain changes, but causation remains unclear
A review of 63 neuroimaging studies found adolescent cannabis users show altered frontoparietal brain structure and function, but adult studies examining onset age gave mixed results, leaving the question of adolescent-specific vulnerability unresolved.
Half a Million Ontario Births Reveal Link Between Prenatal Cannabis and Autism Diagnoses
Among 503,000+ Ontario births, prenatal cannabis exposure was associated with 51% higher autism diagnosis rate in offspring (HR 1.51), though residual confounding cannot be excluded.
Ultra-heavy cannabis users with no other substance use showed elevated psychotic traits and cognitive deficits
Ultra-heavy cannabis users (30,000+ lifetime exposures) from a culture that forbids other substances showed higher schizotypal traits and worse cognitive performance than matched controls, providing unusually clean evidence of cannabis-specific effects.
Heavy recreational cannabis users showed impaired driving even when not high, especially those who started before age 16
Non-intoxicated heavy cannabis users showed impaired simulated driving, but only those who started regular use before age 16. Late-onset users performed similarly to non-using controls.
Prenatal THC selectively damaged hippocampal interneurons in male offspring, explaining sex-specific memory deficits
Prenatal THC exposure selectively destroyed CCK-containing hippocampal interneurons in male but not female mice, causing lasting memory deficits and disrupted brain oscillations through a CB1 receptor-dependent mechanism.
Cannabis use was not associated with cognitive impairment in people with first-episode psychosis
Among 89 first-episode psychosis patients, cannabis users showed no cognitive differences from non-users despite different symptom profiles, with users having more positive and non-users more negative symptoms.
Cannabis users who developed psychosis showed widespread grey matter loss compared to cannabis users without psychosis
A pilot MRI study found cannabis users who developed psychosis had widespread grey matter loss in frontal, temporal, and insular regions compared to non-psychotic cannabis users, suggesting psychosis involves brain changes beyond what cannabis use alone produces.
Review finds cannabis affects the adolescent brain differently than adult brain through disrupted neuronal growth
A review found THC disrupts neuronal growth factor production through CB1 receptors, with adolescent brains showing different structural and behavioral effects than adult brains, compounded by decades of increasing THC potency.
Cannabis combined with anabolic steroid nandrolone produced greater neurotoxicity than either drug alone in adolescent rats
Combining cannabis and the anabolic steroid nandrolone in adolescent rats produced synergistic neurotoxicity: worse cognition, more anxiety and aggression, and greater brain damage through oxidative stress and apoptosis.
Daily THC reduced pain, shrank cysts, and restored memory in a mouse model of endometriosis
Mouse study found daily low-dose THC reduced endometriosis pain, restored memory, and inhibited endometrial cyst growth, suggesting potential disease-modifying effects beyond symptom relief.
Psychosis patients who used cannabis had better social functioning before getting sick
Multisite study of 948 psychosis patients across 6 countries found those who used cannabis had better premorbid social functioning, suggesting social ability may have facilitated cannabis exposure.
Review finds prenatal cannabis exposure linked to attention problems and later psychological issues, not birth defects
Review finds prenatal cannabis exposure is not linked to a unique birth defect pattern but is associated with impaired attention and memory, plus increased depression, anxiety, and delinquency in offspring.
Higher doses of the minor cannabinoid CBN were associated with lower ADHD symptom scores in medical cannabis patients
Small study of 59 ADHD patients using medical cannabis found higher CBN consumption was associated with lower ADHD symptom scores, and higher-dose users more often stopped ADHD medications.
Cannabis concentrates impaired movement speed and balance in frequent users, with effects lasting at least an hour
Study of 65 frequent concentrate users found dabbing impaired arm speed for at least 1 hour and balance immediately, with motor impairment poorly correlated to blood THC levels.
Rat fathers exposed to THC before mating produced offspring with hyperactivity and cognitive deficits
Rat study found offspring of THC-exposed fathers showed hyperactivity and cognitive deficits despite mothers never being exposed, suggesting paternal cannabis use before conception can affect offspring.
Long-term THC shifted brain reward circuit control from rational to emotional regions in rats
Rat study found long-term THC weakened prefrontal cortex control of the brain's reward center while strengthening emotional region (amygdala/hippocampus) input, potentially explaining cannabis-related cognitive and psychiatric effects.
CB1 receptors help the brain choose between navigation strategies
Blocking CB1 receptors in mice impaired spatial learning and shifted navigation strategies, with altered brain activity in the hippocampus, striatum, and amygdala.
How cannabis compounds disrupt timing ability by desynchronizing brain regions
CB1 activation in rats disrupted synchronization between hippocampus and entorhinal cortex, causing time overestimation on a precise timing task.
Cannabis dependence blurs the brain boundary between thinking and feeling
Study of 1,206 young adults found that cannabis dependence, but not recreational use, was associated with a breakdown in normal brain separation between cognitive and emotional processing.
Cannabis impaired divided attention during driving in a simulator study
Driving simulator study found each unit increase in blood THC impaired task completion, accuracy, and lane-keeping during divided-attention tasks, with low alcohol adding further impairment.
Treadmill exercise improved memory through the endocannabinoid system in rats with brain inflammation
Treadmill exercise reversed memory deficits from brain inflammation in rats by modulating CB1/CB2 receptors and inflammatory enzymes in the hippocampus.
Up to 46% of people seeking cannabis addiction treatment may have undiagnosed ADHD
Study of 99 cannabis treatment seekers found ADHD prevalence of 34-46%, far exceeding general population rates, suggesting routine ADHD screening should be standard.
Cannabis may increase psychosis-like traits by disrupting how the brain assigns importance to things
Study of 910 students found cannabis use predicted psychosis-like traits, with aberrant salience (abnormal importance assignment) mediating the relationship.
Cannabis impaired vision and driving ability, and the two were correlated
Study of 20 drivers found cannabis impaired visual acuity, contrast sensitivity, and depth perception, with visual deficits directly correlated with worse driving performance.
Cannabis use disorders linked to 38% higher medication non-compliance in schizophrenia patients
Study of 1M+ schizophrenia inpatients found cannabis use disorders independently associated with 38% higher medication non-compliance after adjustments.
Cannabis misuse linked to ADHD symptoms but not broader cognitive deficits in 1,008 adults
Study of 1,008 adults found cannabis misuse predicted ADHD symptoms (hyperactive and inattentive) but not other cognitive deficits; age of first use showed no cognitive effects.
THC and CBD had opposing effects on how people read emotions in faces, but evidence is limited
Systematic review found THC impaired facial emotion recognition in half of experiments while CBD improved it, with opposing brain activation for threatening faces.
Oral cannabis at 25-50 mg THC markedly impaired cognition in infrequent users, with delayed onset and peak effects
Controlled study found oral cannabis at 25-50 mg THC markedly impaired cognition in infrequent users, with effects delayed 30-60 min and peaking at 1.5-3 hours.
People with schizophrenia and lifetime cannabis use showed greater deficits in emotional expression and anticipating pleasure
Study of 71 schizophrenia patients found lifetime cannabis users had greater deficits in emotional expression, anticipatory pleasure, and social functioning.
Recent trials add evidence for CBD antipsychotic potential, but are not yet sufficient for clinical recommendations
Review of recent trials found CBD reduces positive psychotic symptoms but not negative symptoms, with inconsistent cognitive effects and generally good tolerability.
Paternal THC exposure before conception caused lasting cholinergic brain deficits in rat offspring through middle age
Paternal THC exposure in rats caused dose-dependent, lifelong cholinergic brain deficits in offspring from adolescence through middle age.
Impulsivity and using cannabis to cope with negative emotions were the strongest predictors of heavy daily use
Study of 2,545 cannabis users found impulsivity and coping motives predicted heaviest use (daily, 4+ times), with 36% of users in the highest frequency group.
Genetic analysis finds ADHD causally increases cannabis use risk nearly 8-fold, not the other way around
Molecular Psychiatry study found ADHD genetically causes 8-fold increased cannabis use risk (OR 7.9), with 29% genetic overlap and 4 new shared loci identified.
One year of CBD treatment did not harm cognitive function in children with treatment-resistant epilepsy
An open-label study of 38 children with treatment-resistant epilepsy found no cognitive decline after one year of add-on CBD treatment, with some trends toward improvement.
Chronic CBD treatment did not improve behavioral symptoms in a tau-based Alzheimer's mouse model
Chronic CBD at 50 mg/kg did not improve motor, anxiety, or cognitive measures in 4-month-old TAU58/2 transgenic male mice, despite previous success in amyloid-based AD models.
Cannabis-dependent men performed worse on cognitive tasks under stress, linked to reduced precuneus brain activity
Cannabis-dependent men showed worse cognitive performance under stress with reduced precuneus brain activity, despite experiencing similar levels of subjective stress as controls.
Few high school cannabis users quit on their own, but those who did showed improved attendance and homework completion
A longitudinal study of 91,774 Canadian high school students found few cannabis users quit spontaneously, but those who did showed 2.5x better attendance and 2.3x better homework completion than continuing users.
Teenage Cannabis Use Accelerates Brain Cortex Thinning in the Regions That Matter Most
Longitudinal MRI study of 799 European teenagers found dose-dependent prefrontal cortical thinning associated with cannabis use from age 14 to 19, concentrated in CB1 receptor-rich brain regions.
Endocannabinoid system enzymes MAGL and FAAH show promise as targets for treating Alzheimer's-related cognitive decline
Preclinical research suggests that blocking endocannabinoid-degrading enzymes (MAGL and FAAH) could protect brain cells from Alzheimer's-related damage, reduce inflammation, and potentially improve cognitive function.
Cannabis use disorder in youth is linked to difficulty recognizing sad and fearful facial expressions
A study of 152 youths found that more severe cannabis use disorder was linked to poorer recognition of sad and fearful facial expressions, independent of conduct disorder. This could represent a pathway through which cannabis increases aggression risk.
Regular cannabis use starting in adolescence disrupts brain regions responsible for learning new information
An fMRI study found adolescent-onset cannabis users learned new words significantly slower than non-users. Brain imaging revealed disrupted activation in the parahippocampal gyrus, midbrain, and thalamus during learning.
Cochrane review finds insufficient evidence to determine if cannabinoids help or harm people with dementia
A Cochrane review of four trials (126 participants) found very low to low certainty evidence that cannabinoids have little or no meaningful effect on cognition or behavioral symptoms in dementia. The evidence base is too small for conclusions.
Cannabis users who feel stimulated rather than stoned show less driving impairment
In a small simulator study, cannabis users who felt stimulated showed less driving impairment than those who felt stoned. Subjective experience predicted steering behavior, while actual lane control was predicted by cannabis dose.
Limited evidence does not clearly show cannabis worsens brain outcomes in youth with ADHD
A systematic review of 11 studies found no clear evidence that cannabis compounds cognitive deficits in youth with ADHD, though neuroimaging showed brain differences. The evidence is limited and potentially underpowered.
Nabilone may help agitation in dementia but there is no convincing evidence that cannabinoids help cognition
A systematic review of five trials found the synthetic cannabinoid nabilone may reduce agitation in dementia, but natural THC showed no benefit. No studies have tested cannabinoids for cognitive decline in dementia.
Blocking a key enzyme in Alzheimer's patients' immune cells shifted them from inflammatory to protective
Blocking the enzyme FAAH in immune cells from Alzheimer's patients reduced inflammation and shifted cells toward a protective state, suggesting endocannabinoid system modulation could offer a new therapeutic approach.
Psychotic-like experiences did not predict whether young adults quit or continued cannabis
Tracking 552 young cannabis users from age 19 to 22, psychotic-like experiences did not predict changes in cannabis use, but later age of first use predicted steeper increases.
Cannabis use was not linked to changes in a learning task tied to psychosis, but was linked to higher schizotypy scores
Study of 307 healthy adults found no link between cannabis use and Kamin blocking (an associative learning task impaired in schizophrenia), though current users reported more schizotypy and aberrant salience.
Brain scans show similar abnormalities in schizophrenia patients whether or not they used cannabis
Meta-analysis of 10 MRI studies found schizophrenia patients with and without cannabis use showed overlapping brain volume reductions, with no significant differences between groups.
Brain development differences both predict and result from adolescent substance use
Systematic review of 38 longitudinal studies found that brain development delays, especially in executive functioning, both precede and result from adolescent substance use, with harm tied to frequency and recovery tied to duration.
Medical cannabis patients showed no cognitive impairment 4 hours after THC use across all studies reviewed
Scoping review of seven controlled trials found medical cannabis patients showed THC dose-dependent cognitive decline that fully resolved within 4 hours in every study.
Adults with ADHD symptoms experienced more daily cannabis consequences, especially around sleep use
Daily diary study of 62 cannabis users found those with more ADHD symptoms experienced more daily cannabis consequences, with boredom and sleep motives increasing problems further.
First-episode schizophrenia patients who used cannabis performed better on cognitive tests
Study found that first-episode schizophrenia patients with a history of cannabis use performed better on cognitive tests, especially visual memory, than non-using patients.
Alcohol, but not cannabis, was linked to thinner brain cortex in young adults
Twin study of 436 young adults found alcohol misuse was associated with thinner cortex in cognitive control brain regions, reflecting both genetic predisposition and direct exposure. Cannabis showed no such effects.
Attentional bias training did not improve outcomes for alcohol or cannabis use disorder
Multicenter RCT of 169 people with alcohol or cannabis use disorder found that internet-based attentional bias training added to standard treatment produced no improvements in any outcome over 12 months.
Nicotine may mask cognitive deficits from cannabis use in young people
Systematic review of 12 studies found that nicotine co-use may mask cannabis-related cognitive deficits in young people, while neuroimaging research on co-use effects remains extremely limited.
Vaping a small dose of CBD slightly improved short-term verbal memory in young adults
Small crossover trial found vaping 12.5 mg CBD modestly improved verbal memory recall (0.68 additional words) in 34 healthy young adults without affecting attention or working memory.
Cannabis use in bipolar disorder was mostly not associated with worse cognition
Scoping review of only 6 studies found cannabis use was mostly not associated with cognitive impairment in bipolar disorder, with two studies finding better performance in some domains.
Adolescent CBD exposure in mice caused no harmful behavioral effects in adulthood
Mouse study found twice-daily adolescent CBD exposure caused no harmful effects on locomotion, anxiety, or spatial memory in adulthood, with a possible learning enhancement.
Heavy alcohol and cannabis use during adolescence linked to brain changes and cognitive effects
A systematic review of 43 longitudinal studies found heavy adolescent alcohol use was associated with widespread brain structure changes, while heavy cannabis use showed more localized effects. Co-use studies generally found alcohol effects were more pronounced.
Driving-themed cannabis risk messages captured the most attention and arousal
A psychophysiology study of 50 young adults found that driving-related cannabis risk messages generated the strongest attention, arousal, and emotional engagement compared to messages about cognition or health.
Alcohol addiction linked to blunted brain alpha waves, independent of cannabis use
A MEG study of 45 adults who used both alcohol and cannabis found that alcohol use disorder was associated with blunted occipital alpha brain wave responses, with no independent effect from cannabis use disorder.
Cannabis smoking linked to oral bacteria that caused brain changes in mice
A study found chronic cannabis smokers had elevated oral Actinomyces meyeri bacteria. When this bacterium was fed to mice for six months, it decreased activity and increased amyloid-beta production in their brains.
Heavy cannabis use associated with worse cognitive outcomes in ADHD patients
A chart review of 50 ADHD patients found heavy cannabis use was associated with significantly worse cognitive test performance, more fine motor hyperactivity, and higher self-reported impulsivity compared to ADHD patients without substance use.
ADHD patients seeking cannabis treatment had more anxiety and started substance use younger
Among 239 ADHD patients with substance use disorders, those seeking cannabis treatment had more anxiety, earlier substance use onset, and similar ADHD severity compared to those seeking cocaine treatment.
THC impairs driving-related skills for about 3-5 hours after inhaling, longer after eating
A meta-analysis of 80 studies found THC impairs driving-related skills at peak effect, with impairment from inhaled cannabis generally resolving within 3-5 hours. Researchers recommended waiting at least 5 hours before driving.
Children exposed to marijuana before birth showed more behavioral problems by age 3.5
Children exposed to marijuana before birth showed more sleep problems, withdrawal symptoms, and aggressive behaviors at age 3.5 compared to non-exposed children, but executive function was not affected.
Cannabis use and depression affected different brain regions during emotion regulation
An fMRI study of 74 young adults found that depression and cannabis use each independently altered brain activation during emotion regulation, but in different temporal lobe regions.
How does cannabis-induced psychosis differ from schizophrenia?
Comparative study finds cannabis-induced psychosis and schizophrenia have distinct symptom profiles, with different patterns of speech and thought disorder.
Does frequent cannabis use affect thinking skills in heavy-drinking young adults?
Study of 598 heavy-drinking young adults finds daily cannabis use linked to modestly poorer working memory and more impulsivity, while occasional use showed no deficits.
Is prenatal cannabis exposure associated with behavioral and cognitive differences in children?
ABCD study of 11,489 children finds prenatal cannabis exposure associated with greater psychopathology, sleep problems, higher BMI, and lower cognition at ages 9-11.
Does cannabis use affect working memory through changes in hippocampal size?
Brain scan study of 408 individuals finds cannabis use frequency linked to smaller hippocampal volume, which mediated the relationship with working memory impairment.
Does daily cannabis use specifically affect impulsivity and ADHD symptoms in binge drinkers?
Study of 730 binge-drinking young adults finds daily cannabis use linked to impulsive reward choice and hyperactive ADHD symptoms, with no effects from occasional use.
How does recent cannabis use affect symptoms in first-episode psychosis?
Study of 247 first-episode psychosis patients finds cannabis users had less social withdrawal but more severe delusions, with no cognitive differences.
Cannabis Affects Male and Female Brains Differently on Cognitive Tests
Study of 171 young regular cannabis users found sex-specific cognitive effects: males had poorer visual memory while females showed worse attention and executive function, with effect sizes in the medium-to-large range.
Cannabis-Induced Psychosis Shows Less Cognitive Damage Than Schizophrenia
Study comparing 20 cannabis-induced psychosis patients to 20 schizophrenia-with-cannabis patients found CIP showed significantly better intelligence and attention, with cognitive deficits limited to some executive function domains.
Cannabis Use in Healthy People Linked to Psychosis and Impaired Functioning
Systematic review of 124 studies found cannabis use in healthy people was linked to adverse effects on psychosis risk, cognition, mood, and functioning, driven by THC content, frequency, and age of onset.
Field Sobriety Tests Failed to Detect Cannabis Impairment
Controlled study found standard field sobriety tests failed to detect cannabis impairment, while a novel app (DRUID) reliably identified it. Blood THC levels returned to baseline before impairment resolved.
Synthetic Cannabinoid JWH-018 Impaired Attention, Memory, and Motor Control
Controlled study found the synthetic cannabinoid JWH-018 at a relatively low dose significantly impaired motor coordination, attention, memory, and response speed in 24 cannabis-experienced adults.
Heavy cannabis users showed accelerated cerebellar thickening over 3 years compared to non-users
Three-year MRI study found heavy cannabis users showed accelerated cerebellar thickening in regions linked to cognition and motor control, with changes tied to earlier onset of cannabis use.
Older cannabis users showed higher fall risk, worse balance, and slower walking than non-users
Small study of 16 older adults found chronic cannabis users had higher fall risk, worse balance, and slower walking speed than matched non-users, though cognitive function was similar.
Nano-coated CBD reduced Alzheimer-like brain plaques and improved memory in rats
Nano-chitosan-coated CBD reduced amyloid plaques, increased brain cannabinoid receptors, and improved memory performance in an Alzheimer rat model.
Cannabis use in first-episode psychosis overwhelmed the protective effects of cognitive reserve on functioning
In first-episode psychosis, cognitive reserve protected against poor outcomes only in non-cannabis users, suggesting cannabis overwhelms the brain's built-in cognitive resilience.
Rat study finds high-THC cannabis smoke impairs working memory but not attention, while high-CBD smoke does not
A rat study found high-THC cannabis smoke impaired working memory but not attention, while high-CBD smoke caused no cognitive deficits.
Boosting anandamide in adolescent rats reversed schizophrenia-like cognitive and social deficits through CB1 and CB2 receptors
Boosting anandamide in adolescent rats reversed schizophrenia-like cognitive and social deficits through distinct CB1 and CB2 receptor pathways.
Edible and flower cannabis users showed similar intoxication and memory impairment despite different blood THC levels
A naturalistic study found flower and edible cannabis users reached similar levels of intoxication and memory impairment despite flower users having higher blood THC levels.
How stoned drivers feel predicts driving performance beyond THC dose alone, but the specific predictors vary
A driving study found self-reported cannabis effects predicted driving performance beyond THC dose, but which feelings mattered varied between studies, with "stoned" being the most consistent.
Marijuana improved spatial learning in both young and old female rats, but combined with estrogen had negative effects in older rats
Marijuana improved spatial learning in female rats, but combining it with estrogen in older rats produced negative cognitive effects through the GPR30 receptor.
Prenatal cannabis exposure linked to attention and behavior problems at age 10 but no brain scan differences
In the ABCD Study, prenatal cannabis exposure was linked to more attention and behavior problems at ages 9-10, but no differences in cognitive performance or brain scans.
Women with ADHD and substance use disorders started cannabis earlier and used it longer than those without ADHD
Among substance use disorder patients, women with ADHD started cannabis use earlier and used longer than any other group, highlighting a gender-specific vulnerability.
Adolescent cannabis vapor exposure produced opposite brain changes in male and female mice on MRI
Adolescent cannabis vapor exposure produced opposite brain changes in male and female mice: structural changes in females and functional connectivity disruption with cognitive deficits in males.
Clinical guideline recommends atomoxetine for ADHD with cannabis use disorder but finds it does not reduce cannabis use itself
A clinical guideline recommends atomoxetine for ADHD symptoms in patients with cannabis use disorder but finds it does not reduce cannabis use. Both atomoxetine and stimulants are considered safe in SUD patients.
Open-label trial finds full-spectrum CBD reduced anxiety significantly within one week, with cognitive improvements
An open-label trial of full-spectrum CBD in 14 anxiety patients showed rapid response within one week, with improvements in anxiety, cognition, mood, and sleep over 4 weeks.
Cannabis users show higher schizotypy traits and aberrant salience but normal salience processing on lab tasks
Cannabis users reported more schizotypy traits and subjective aberrant salience experiences, but showed normal salience processing on an objective lab task.
Two long-term cannabis users had vitamin deficiencies and low cortisol
Two long-term cannabis users had vitamin deficiencies and low cortisol that improved with supplements and psychotherapy.
Long-term effects of prenatal cannabis exposure from childhood through adulthood
Longitudinal research links prenatal cannabis exposure to lasting effects on behavior, memory, and substance use from childhood through adulthood.
CBD shows early promise for neurodevelopmental disorders in children
Review finds early evidence that CBD may safely improve symptoms of autism, intellectual disability, tics, and ADHD in children and adolescents.
Chronic cannabis use may impair the brain's error-correction system through the cerebellum
Review and computational model suggest chronic cannabis use impairs the cerebellum's ability to process sensory errors, explaining observed motor learning deficits.
Regular cannabis users showed better facial emotion recognition, including those with schizophrenia
Large study of 6,229 people found lifetime cannabis use was linked to better facial emotion recognition across schizophrenia patients, siblings, and healthy controls.
Schizophrenia with heavy cannabis use showed different brain structure than cannabis-induced psychosis
Brain imaging showed schizophrenia patients with cannabis use had thinner cortex than cannabis-induced psychosis patients, supporting distinct pathophysiology.
Where THC acts in the brain depends on dose and how many cannabinoid receptors are present
Meta-analysis of 372 participants found THC's brain effects are dose-dependent and track with CB1 receptor density across regions.
Large meta-analysis maps how youth cannabis use changes brain activation patterns
Meta-analysis of 45 fMRI studies (2,702 youth) found cannabis users showed altered activation in prefrontal and cingulate regions, varying by sex, severity, and psychiatric comorbidity.
Workplace Cannabis Policies: A Moving Target
Employers face conflicting laws and unreliable drug tests — a practical framework for cannabis workplace policies addresses safety, legal protections, and impairment measurement.
Why people with ADHD may use cannabis therapeutically and what research says about it
People with ADHD may use cannabis to manage self-regulation deficits, but evidence for therapeutic benefit is limited and the risk of problematic use is elevated.
Brain imaging reveals distinct structural, functional, and neurochemical signatures of heavy cannabis use
Multimodal brain imaging of 24 heavy cannabis users found distinct structural and functional changes linked to serotonin, dopamine, and opioid receptor systems.
ADHD symptoms in college students predict continued cannabis use but not new initiation
Among 4,270 French students, ADHD symptoms predicted continued cannabis use after one year but did not drive new cannabis initiation.
Even frequent cannabis users show psychomotor impairment right after use, but recover within an hour
Frequent cannabis users showed peak psychomotor impairment immediately after smoking but recovered significantly within one hour, replicated across two studies.
Cannabis users had worse verbal memory but adolescents were not more vulnerable than adults
Cannabis users showed worse verbal memory than controls, but adolescent users (16-17) were not more impaired than adult users (26-29), challenging the adolescent vulnerability hypothesis.
Adolescent THC caused lasting memory deficits in female rodents by disrupting synaptic plasticity and estrogen signaling
Adolescent THC exposure caused lasting, sex-specific hippocampal damage in rodents, with females more severely affected through disrupted estrogen-endocannabinoid signaling.
Cannabis Use Linked to Weaker Brain Connectivity in Adults with Childhood ADHD
Brain imaging found adults with childhood ADHD who used cannabis had weaker thalamus-parietal connections than non-users, while non-users had stronger-than-typical connectivity in these regions.
Massive Review: How Cannabis Affects the Developing Adolescent Brain
The largest neuroimaging review of adolescent cannabis use (90 studies, 9,441 participants) found evidence of altered brain structure and function in frontoparietal, frontolimbic, frontostriatal, and cerebellar regions.
Alcohol and Cannabis Together Shrank Brain Gray Matter Faster Than Either Alone
Longitudinal brain imaging of 724 adolescents found combined alcohol and cannabis use accelerated gray matter decline in five brain regions, with neither substance alone producing the same effect.
Cannabis Impaired Simulated Driving for Hours, but Users Felt Ready to Drive Too Soon
RCT of 191 regular cannabis users found simulated driving impairment lasted up to 3.5 hours, but 69% felt ready to drive at 1.5 hours. THC content and use history did not predict impairment level.
CBD Up to 1,500 mg Did Not Impair Driving or Cognitive Function in a Crossover Trial
Crossover RCT found oral CBD up to 1,500 mg did not impair simulated driving or cognition compared to placebo, though high-dose CBD persisted in blood for over 4 weeks.
Long-Term Cannabis Users Lost 5.5 IQ Points and Had Smaller Hippocampi by Midlife
A 45-year cohort study found long-term cannabis users lost 5.5 IQ points from childhood, had poorer learning and processing speed, and smaller hippocampi by midlife, specific to cannabis over other substances.
Cannabis Use Did Not Interfere with Cognitive Behavioral Therapy for Insomnia
In young adult binge drinkers with insomnia, cannabis use during CBT-I treatment did not reduce therapy effectiveness, with virtually zero moderation effect on outcomes.
Adolescents Were More Cognitively Impaired by THC Than Adults at the Same Doses
RCT found adolescents (18-20) showed cognitive impairments and brain wave changes from THC that adults (30-40) did not, despite both groups feeling equally intoxicated.
Both Alcohol and Cannabis Impaired Vision, but Only Higher Alcohol Doses Worsened Driving
Experimental study found both alcohol and cannabis impaired visual function, but only the higher alcohol dose (450 ml wine) significantly worsened driving simulator performance.
Bayesian Modeling Suggests Adolescent Cannabis Use Causes Faster Brain Cortex Thinning
Causal modeling of 637 IMAGEN study adolescents found a directional relationship from cannabis use to accelerated prefrontal cortical thinning, consistent with cannabis affecting brain development.
Genetic Predisposition to Cannabis Use Was Linked to Higher Cognitive Scores in Children
Among 3,205 substance-naive children, higher genetic risk for lifetime cannabis use was associated with better cognitive scores, suggesting shared genetic overlap with traits like curiosity rather than a cannabis benefit.
THC/CBD for Severe Dementia Behavioral Symptoms: A Two-Year Safety Pilot
Two years of THC/CBD treatment in 19 elderly dementia patients showed good safety and reduced behavioral symptoms, but without a control group, the benefits remain unproven.
Clinical Assessments Predicted Continued Cannabis Use in Psychosis Patients with 73% Accuracy
Machine learning predicted continued cannabis use in psychosis patients with 73% accuracy using clinical interviews alone. Lower functioning and lack of coping strategies were key predictors.
Genetic Variants for Substance Use and Brain Structure Share Common Pathways
Genetics study found shared genetic links between brain cortical structure and substance use behaviors, with cannabis use genetics correlating with insula surface area differences.
Cannabis use did not worsen cognition in first-episode schizophrenia, but methamphetamine did
Two-year study found methamphetamine, but not cannabis, predicted worse cognitive outcomes in first-episode schizophrenia patients.
Veterans with bipolar disorder who currently used cannabis had better working memory and functioning
Study of 254 veterans with bipolar disorder found current cannabis users had better working memory and functioning than past or non-users, but also higher rates of PTSD and suicidal ideation.
Cannabis ex-users with first-episode psychosis recovered attention closest to healthy levels over 3 years
Three-year study of 461 first-episode psychosis patients found those who quit cannabis showed the most attention recovery, reaching scores closest to healthy controls.
Brain imaging showed less damage in cannabis-induced psychosis compared to schizophrenia with cannabis use
Brain imaging study of 60 participants found cannabis-induced psychosis had fewer white matter abnormalities and more gray matter than schizophrenia with cannabis use.
Meta-analysis of 57 studies confirmed cannabis impairs driving, comparable to low blood alcohol
Meta-analysis of 57 driving studies found cannabis impairs lane control at levels comparable to low blood alcohol, with cannabis plus alcohol producing the worst impairment.
Largest fMRI study found no reward processing differences between cannabis users and non-users
Largest fMRI study of cannabis and reward processing (125 participants) found no differences between users and non-users in reward anticipation, with adolescents showing no extra vulnerability.
THC improved memory and movement recovery after traumatic brain injury in mice
Mice given THC for 3 days after brain injury recovered working memory and motor function, with increased brain repair factors BDNF, GDNF, and G-CSF.
Students with ADHD reported cannabis helped with hyperactivity, impulsivity, and medication side effects
Survey of 1,738 students found those with ADHD reported cannabis helped with hyperactivity, impulsivity, and medication side effects, with frequent use moderating executive dysfunction.
In-utero cannabis exposure was not associated with ADHD risk in a Quebec birth cohort
Quebec cohort study of 2,408 children found no significant association between in-utero cannabis exposure and ADHD risk after adjusting for confounders.
American Heart Association statement warned marijuana may adversely affect brain health
American Heart Association scientific statement concluded marijuana may adversely affect brain health through cognitive impairment and increased stroke risk, especially during neurodevelopment.
Measuring Exactly How Much THC You Actually Smoke: A New Field Testing Method
A portable potency tester combined with real-time tracking created the first practical standard THC unit measure — higher milligram doses correlated with greater intoxication.
Alcohol Impairs Thinking While Cannabis Mainly Shifts Mood, Study Finds
Controlled trial of 28 young adults found cannabis mainly affects mood and subjective experience while alcohol primarily impairs cognition and motor performance. Combined effects were additive at most.
Chronic Cannabis Use in Teens Linked to DNA Changes That May Affect Verbal Memory
Small study of 18 adolescents found chronic cannabis use linked to DNA methylation changes at six sites that statistically mediated lower verbal memory scores.
Most Evidence Suggests Medical Cannabis Has Minor Effects on Thinking Skills
Systematic review of 23 studies (917 participants) found most high-quality evidence suggests medical cannabis has minor cognitive effects at low to moderate THC doses.
Cannabis Effects on Cognition Depend Heavily on Age: Harmful for Young Brains, Possibly Helpful in Old Age
Scoping review of animal studies found cannabinoid exposure during brain development (prenatal, adolescent) caused lasting cognitive harm, while exposure in old age showed potential cognitive benefits.
Adolescent Alcohol, Cannabis, and Nicotine Combined Caused Long-Term Learning Deficits in Rats
Rats exposed to combined alcohol, cannabinoid, and nicotine during adolescence showed lasting learning deficits in adulthood, with females affected earlier than males.
Cannabis Users Were More Willing to Work for Rewards, Contradicting the "Amotivational Syndrome" Idea
Study of 47 college students found cannabis users were more likely to choose harder tasks for rewards, contradicting the "amotivational syndrome" hypothesis.
10-Year Study Shows Adolescent Cannabis Use Linked to Different Brain Changes Than Young Adult Use
10-year study of 704 people found adolescent cannabis initiation caused prefrontal cortex thinning linked to later drug use, while young adult initiation affected temporal areas linked to psychotic symptoms.
Prescribed Medical Cannabis Had Minimal Impact on Cognitive Performance in Patients
Trial of 40 medical cannabis patients found no cognitive impairment after standard prescribed doses, with some test scores actually improving, though vaporized flower felt more impairing subjectively.
Cannabis use linked to lower levels of a psychosis-associated brain enzyme
Translational study found psychosis patients with prior cannabis use had lower CDK5 (a psychosis-linked enzyme) and fewer social deficits than those without cannabis history.
Repeated exposure to a synthetic cannabinoid caused lasting cognitive and brain changes in mice
Mouse study found 7 days of synthetic cannabinoid JWH-018 produced psychotic-like symptoms and lasting brain changes in memory, social behavior, and neuroplasticity persisting 15+ days after stopping.
Synthetic cannabinoid caused lasting brain metabolism changes and memory deficits in adult mice
Mouse study found synthetic cannabinoid WIN 55,212-2 caused lasting brain metabolism reductions and memory deficits that persisted after prolonged abstinence, especially when exposure occurred in early adulthood.
Cannabis products labeled indica and sativa had different effects on cognitive effort in rats
Rats given oral cannabis oil labeled indica were less willing to exert cognitive effort for rewards compared to sativa-labeled oil with identical THC/CBD content, suggesting other compounds matter.
CBD improved memory in adolescent rats that were exposed to THC before birth
CBD given during adolescence rescued memory deficits and restored brain plasticity markers in rats prenatally exposed to THC, suggesting a potential therapeutic window.
Genetic evidence suggests cannabis use disorder may lower educational attainment, while education reduces disorder risk
Genetic analysis found cannabis use disorder may reduce education by 1.2 months, while higher education was associated with more lifetime cannabis use but 61% lower disorder risk.
Can Cannabis Users Tell When They're Too High to Drive? Mostly Yes, Actually
Cannabis users accurately predicted their driving impairment after THC inhalation — self-rated confidence correlated with actual simulator performance and THC dose.
Long-Term Marijuana Use Was Linked to DNA Changes in Genes Related to Schizophrenia, Bipolar Disorder, and Cell Growth
A longitudinal study of 1,000+ adults found marijuana use was associated with DNA methylation changes in genes related to schizophrenia, bipolar disorder, cell proliferation, and hormone signaling.
Review Proposes a New Model of Adolescent Cannabis Use Disorder Based on Drug, Mindset, and Environment Interactions
Narrative review proposes adolescent CUD develops through feedback loops between drug characteristics, individual mindset, and environmental setting.
Cannabis-Impaired Drivers Did Not Slow Down to Compensate for Their Impairment
Study of 31 cannabis users found significant visual impairment after use but no compensatory speed reduction.
Preclinical Studies Support CBD for Cognitive Impairment, but Human Evidence Is Still Missing
Review found strong preclinical evidence for CBD improving cognition, but human studies have not confirmed these effects.
Prenatal THC Exposure Altered Hippocampal Development in Mice Through a Specific Gene Pathway
Prenatal THC altered mouse hippocampal development through the CB1 receptor and MEF2C pathway, with effects rescued by a CB1 blocker.
Prenatal Cannabinoid Exposure Caused Memory Deficits in Adolescent Rats by Disrupting a Key Neural Adhesion Molecule
Prenatal cannabinoid exposure caused adolescent rat memory deficits through reduced PSA-NCAM and imbalanced glutamate signaling, with PSA administration rescuing the impairment.
How Cannabis Tolerance Builds: What Happens to Your Brain's CB1 Receptors
Chronic cannabis use reduces CB1 receptor number and responsiveness throughout the brain — with significant sex differences — explaining why the same dose stops working over time.
A Review of How Adolescent Cannabis Use Disrupts Brain Development Amid Expanding Legal Access to High-Potency Products
Review found adolescent cannabis use disrupts critical brain development, with concern that new high-potency products and delivery devices amplify the risk.
A Review of How Combined Alcohol and Cannabis Use During Pregnancy May Compound Risks to Fetal Brain Development
Review highlighted that combined alcohol-cannabis use during pregnancy is increasingly common but virtually unstudied, despite evidence that co-use amplifies effects.
CBD Extended Sleep Duration in Rats but Disrupted Sleep Oscillations Needed for Complex Memory Consolidation
CBD extended sleep in rats but disrupted sleep oscillations critical for memory, impairing complex memory consolidation while leaving simple memory intact.
Prenatal Cannabis Smoke Exposure Altered Sex Ratio, Increased Anxiety, and Changed Gene Expression in Rat Offspring
Prenatal cannabis smoke exposure in rats altered litter sex ratio, increased adult offspring anxiety, changed amygdala genes, but improved some cognitive tasks.
Adolescent THC Edible Experience Made Alcohol's Stimulant Effects Stronger in Rats and Changed Brain Endocannabinoid Levels
Adolescent THC edible experience in rats enhanced alcohol's stimulant effects and altered frontal cortex endocannabinoid levels during alcohol withdrawal.
Prenatal THC Caused Long-Term Cognitive Problems in Rat Offspring Through Sex-Specific Mechanisms in the Prefrontal Cortex and Hippocampus
Prenatal THC caused lasting cognitive deficits in both male and female rats through radically different sex-specific mechanisms involving neural activity, proteins, and fatty acid depletion.
A Review Found Adolescent Cannabis Use Causes Lasting Cognitive Changes Through Epigenetic and Synaptic Mechanisms
Review found adolescent cannabis use causes lasting cognitive changes through epigenetic modifications and synaptic disruptions, worsened by high-potency products and early initiation.
A Comprehensive Review of CBD's Effects on Brain Function Found Promise for Multiple Conditions but Called for Better Regulation
Comprehensive review found CBD has documented benefits for epilepsy, anxiety, and pain, with emerging evidence for cognition and sleep, but called for better product regulation.
A Review Found Converging Evidence That Adolescent Cannabis Use Reduces Cognition, But Debate Continues Over Reversibility
Review found converging evidence that frequent adolescent cannabis use reduces cognition, but debate continues about whether effects persist after quitting and whether brain imaging findings replicate.
Tablet-based tests detected cognitive impairment after smoking cannabis
Tablet-based cognitive test battery detected acute cannabis impairment, with occasional users showing larger deficits than daily users across four cognitive domains.
Babies exposed to cannabis late in pregnancy scored higher on language tests at 12 months
Prospective cohort found late prenatal cannabis exposure associated with higher language scores at 12 months in 69 exposed vs. 138 unexposed infants.
CB1 receptor expression changed in brain immune cells of an Alzheimer's mouse model
Electron microscopy study found CB1 receptor expression increases in reactive microglia but stays proportionally constant in astrocytes in an Alzheimer's mouse model.
Poor decision-making under known risk predicted escalating cannabis use in Hispanic adolescents
2-year longitudinal study of 401 Hispanic adolescents found poor explicit-risk decision-making predicted escalating cannabis use and related problems.
Systematic review found no clear link between prenatal cannabis and child cognitive outcomes
Systematic review of 28 studies (523,107 patients) found no significant pooled associations between prenatal cannabis exposure and child cognitive or academic outcomes.
Cannabis use among North American college students linked to worse psychosocial functioning
Cross-sectional study finds cannabis use linked to adverse psychosocial functioning among North American college students, extending adolescent findings to ages 18-22.
Secondhand cannabis and tobacco exposure linked to lower cognitive scores in youth
ABCD Study of 5,580 youth found secondhand cannabis and tobacco smoke exposure associated with lower cognitive scores, even without direct use.
Neuropsychological testing may help tell cannabis-induced psychosis apart from schizophrenia
Review proposes neuropsychological testing to differentiate cannabis-induced psychosis from schizophrenia, conditions that often look identical clinically.
Synthetic cannabinoid AB-FUBINACA damaged memory and hippocampal cells in mice
Mouse study showed the synthetic cannabinoid AB-FUBINACA damaged hippocampal cells and impaired memory through oxidative stress, inflammation, and reduced BDNF and NMDA receptor expression.
Little evidence that cannabis harms cognition in people with HIV
Systematic review found little evidence that cannabis harms cognition in people with HIV, with potential anti-inflammatory benefits and effects varying by cognitive domain.
How cannabinoids affect long-term memory formation through synaptic plasticity
Review found cannabinoid effects on memory and synaptic plasticity are contradictory, depending on dose, timing, brain region, and receptor interactions, highlighting biological complexity.
Frequent cannabis users reported impaired sensory filtering and altered body awareness
Frequent cannabis users reported difficulty filtering sensory stimuli and heightened emotional body awareness compared to non-users, with effects increasing with more use days.
Cannabis use disorder linked to greater apathy in people living with HIV
Among 311 adults with HIV, current cannabis use disorder was linked to higher apathy scores, but the association disappeared after accounting for depression, suggesting the relationship may be driven by overlapping symptoms.
Daily cannabis users show tolerance to some acute cognitive effects but not all
Occasional cannabis users showed impaired reaction time and memory after smoking, while daily users showed tolerance to these effects but still took longer on a driving-related decision task without losing accuracy.
Prenatal THC exposure disrupted spatial memory in adolescent male rats more than females
Prenatal THC exposure impaired spatial memory more severely in adolescent male rats than females, with males losing hippocampal inhibitory interneurons while females gained them, suggesting fundamentally different biological responses.
Non-medical cannabis use linked to dramatically lower self-reported cognitive decline in older adults
BRFSS survey of 4,744 adults aged 45+ found non-medical cannabis use associated with 96% lower odds of self-reported cognitive decline, though the extreme effect size likely reflects selection bias rather than a true protective effect.
Weekly cannabis use in childhood accelerated biological aging by up to 3.8 years into adulthood
Longitudinal study of 381 people found weekly childhood cannabis use and depression independently accelerated DNA methylation aging from adolescence to adulthood, with combined effects equivalent to 3-4 extra years of biological aging.
How Chronic Pain Rewires the Brain's Reward System — And Why That Makes Cannabis and Opioid Misuse More Likely
Chronic pain and addiction share a common neurobiological root — reduced dopamine signaling — explaining why pain patients who self-medicate with opioids or cannabis are vulnerable to escalating into misuse.
THC withdrawal in mice disrupted both motivation and attention, but only motivational deficits persisted during abstinence
Mouse study found THC withdrawal disrupted both motivation and attention, but during abstinence only motivational deficits persisted, suggesting these are qualitatively distinct withdrawal states.
Veterans with both TBI and cannabis use disorder had over 3 times the risk of cognitive disorders compared to those with neither
Among 1.56 million Veterans, those with both TBI and cannabis use disorder had 3.26 times higher cognitive disorder risk, suggesting the combination compounds vulnerability to early-onset cognitive decline.
Meta-analysis found about 1 in 4 people with ADHD have had cannabis use disorder in their lifetime
Meta-analysis of 14 studies found 26.9% lifetime prevalence of cannabis use disorder in people with ADHD, with nearly 3 times higher risk compared to the general population.
THC shifted attention toward cannabis cues in a controlled vaping experiment with teens and adults
A crossover RCT with 48 cannabis users found THC eliminated the tendency to look away from cannabis images. CBD did not change this effect, and adolescents responded similarly to adults.
Boys exposed to cannabis before birth showed language and cognitive delays at age three
A matched case-control study found prenatal cannabis exposure was linked to lower cognitive and motor scores at age three, with the most severe delays in language development among boys.
Schizophrenia patients with cannabis history showed better cognitive performance and more brain activity than non-users
An fMRI study found first-episode schizophrenia patients with cannabis history had better cognitive control and higher prefrontal brain activity than non-cannabis-using patients.
An 8-Year Study Tracked Whether Light Cannabis Use Changes the Adolescent Brain
An 8-year study found that light cannabis use in late adolescence was associated with conduct problems but not with cognitive decline or changes in reward-related brain activity.
Brain Wiring Differences in People With Cannabis Use Disorder
An MRI study found that people with cannabis use disorder had increased structural brain connectivity in some regions and decreased white matter density in others.
CBD Improved Memory in a Rat Model of Fragile X Syndrome Through a Specific Brain Receptor
CBD rescued memory deficits in Fragile X model rats through hippocampal GPR55 receptors, pointing to a specific mechanism for cognitive benefits in neurodevelopmental disorders.
How Cannabis Affects Eye Movements Relevant to Driving
A systematic review found THC acutely impairs eye movement control and chronic cannabis users show lasting visual scanning deficits, with potential for roadside impairment testing.
A Clinical Trial Testing Whether a High-CBD Cannabis Oil Affects Thinking and Mood
A placebo-controlled trial found that a single dose of a high-CBD medicinal cannabis oil mildly impaired some memory tasks while improving mood in 31 healthy adults.
What Preclinical Evidence Says About CBD for Alzheimer's Disease
Lab and animal studies show CBD may protect against Alzheimer's-related neurodegeneration, but no controlled human trials have been conducted.
Four weeks without cannabis reversed brain network changes and improved cognition in people with MS
Four weeks of cannabis abstinence restored default mode network activity and improved cognition across multiple domains in people with MS who were frequent users.
How Cannabis May Change the Adolescent Brain at the Cellular Level
A translational study connecting mouse neuroscience with human brain imaging identified specific genes and cell types that may explain cannabis-related cortical thinning in adolescents.
Mouse Model of Prenatal THC Exposure Shows Anxiety, Depression, and Increased Alcohol Preference in Offspring
A mouse model of high-dose prenatal THC exposure found offspring developed anxiety, depression, cognitive problems, and increased alcohol preference, with sex-dependent effects.
CBD Did Not Block THC's Effect on Attentional Bias Toward Cannabis Cues
Crossover trial: THC increased attentional bias toward cannabis cues; CBD at three doses did not help.
Preschool Self-Control Problems Linked to Teen E-Cigarette Use Through Harsher Parenting
Preschool executive control problems predicted harsher parenting in adolescence, which in turn predicted higher teen e-cigarette use, though not cannabis or alcohol use.
Vaporized THC During Pregnancy Impaired Attention in Rat Offspring, Especially at Low Doses
First study using vaporized prenatal THC found decreased attention in rat offspring, with low doses producing more pronounced effects than high doses.
Prenatal Tobacco-Cannabis Co-Exposure Affected Children's Emotion Regulation Through Ongoing Maternal Risk Factors
Prenatal tobacco-cannabis co-exposure affected children's emotional regulation primarily through ongoing maternal stress and substance use, not direct prenatal effects. Sensitive parenting buffered risks.
Childhood Neglect Predicted Teen Cannabis Use Through Impulsive Decision-Making
Neglected adolescents were more likely to develop impulsive decision-making that led to increased cannabis use over time, identifying a specific prevention target.
Three Synthetic Cannabinoids Caused Lasting Anxiety, Motor Problems, and Memory Impairment in Mice
Three synthetic cannabinoids caused prolonged anxiety, motor disruption, and endocannabinoid system dysregulation in mice, with one also impairing memory.
Cannabis Users With Psychosis Show Fewer Cognitive Biases Than Non-Users
In the large EU-GEI study, cannabis users showed fewer cognitive biases than non-users, while low-potency cannabis was paradoxically linked to more biases than high-potency use.
Marijuana Use Linked to Lower College Completion Rates, Especially at Four-Year Schools
Nationally representative longitudinal study found past-year marijuana use associated with 30% lower college completion at four-year schools, with dose-response effects.
Current and Former Cannabis Users Report Worse Cognitive Function Than Never-Users in National Survey
National survey of 36,309 adults found current cannabis users reported worst cognitive function, former users were intermediate, and never-users best, suggesting partial recovery after quitting.
Scoping Review Finds Growing Evidence Linking the Endocannabinoid System to ADHD Pathophysiology
Scoping review found growing evidence linking endocannabinoid system dysfunction to ADHD, potentially explaining both high cannabis use rates and popular perception of cannabis as therapeutic for ADHD.
Systematic Review Finds Cannabis Exposure in Youth Linked to Mood Changes Through Permanent Cognitive Alterations
Systematic review of 19 studies found youth cannabis exposure linked to effects from transient mood changes to permanent cognitive alterations, though most evidence comes from animal studies.
CBD Improved Theory of Mind While THC Reduced Cognitive Empathy in Chronic Cannabis Users
In a crossover trial, CBD improved Theory of Mind vs placebo while THC reduced cognitive empathy vs CBD in 18 chronic cannabis users, the first evidence that CBD enhances social cognition.
Prenatal Cannabis Exposure Linked to Attention and Behavior Problems in Children
Evidence summary found prenatal cannabis exposure associated with attention problems, hyperactivity, memory challenges, and diminished academic performance in children, though confounders limit causal conclusions.
Prenatal Cannabis Co-Exposure With Tobacco Had Mixed Effects on Children's Attention and Memory
Study of 133 children found prenatal tobacco exposure increased impulsive responding, but adding cannabis did not worsen effects. Unexpectedly, co-exposed children scored higher on short-term memory.
Prenatal Cannabis Linked to Preterm Birth, Low Birth Weight, and NICU Stays
Meta-analysis of 57 studies found prenatal cannabis exposure increased risks of preterm birth (68%), low birth weight (160%), and NICU admission (151%), with limited cognitive effects beyond attention problems.
Cannabinoid Treatment Reduced Alzheimer's Plaques and Improved Memory in Mice
Ninety-day cannabinoid treatment in Alzheimer's model mice reduced amyloid plaque deposits, improved memory, and decreased brain inflammation markers.
Medicinal Cannabis for Sleep Did Not Impair Next-Day Driving or Cognition
Crossover trial found no meaningful next-day impairment in cognition, psychomotor function, or simulated driving after adults with insomnia took 10mg THC + 200mg CBD oil the previous evening.
Prenatal Cannabis Exposure Linked to Higher ADHD and Autism Risk in Children
Meta-analysis of 14 studies found prenatal cannabis exposure associated with higher ADHD symptom scores and a 30% increased risk of autism, involving over 200,000 participants.
People With ADHD Start Using Cannabis and Other Drugs Earlier
Study of 140 adults in addiction treatment found those with ADHD started substance use younger and had higher rates of cannabis, alcohol, and methamphetamine use.
More Cannabis Use Linked to Modest Cognitive Dips in Young Adults
Study of 225 young adults found greater cannabis use linked to small reductions in emotional processing speed and working memory, with modest age-of-onset effects but no sex differences.
Hair Testing Reveals Stronger Links Between Teen Cannabis Use and Memory Problems Than Self-Report Alone
Hair testing for THC metabolites in 13- to 14-year-olds revealed cognitive deficits in memory, verbal ability, and inhibitory control that self-reported cannabis use alone did not capture.
Cannabis Users with Trauma Have 15-20% More of a Key Brain Receptor Linked to Both Conditions
PET imaging shows cannabis users with trauma have 15-20% higher mGlu5 glutamate receptors in frontal and limbic brain regions — a molecular link between the endocannabinoid and glutamate systems.
Brain Networks Linked to Poor Sustained Attention at Age 14 Predicted Cannabis and Cigarette Use by Age 23
Brain connectivity patterns linked to poor sustained attention at age 14 predicted increases in cannabis and cigarette use through age 23, suggesting attention deficits precede substance use.
Review of 14 Randomized Trials Finds CBD Shows Promise for Anxiety and Cognition, But Evidence Is Mixed
Review of 14 randomized trials found CBD improved anxiety and cognition in 9 of 16 outcomes, with oral doses of 200-1,500 mg showing efficacy and a good safety profile.
Cannabis Improved Working Memory in Aged Rats But Not Young Ones, With Sex Differences in Smoke Exposure
Both cannabis smoke and oral THC improved working memory in aged rats without affecting young adults, suggesting cannabinoids may compensate for age-related cognitive decline.
Young Adults With Cannabis Use Disorder Show Normal Social Cognition
Study of 115 young adults found no social cognition deficits in those with cannabis use disorder compared to controls, even after accounting for dosage, recency of use, and other substance use.
Young Adults With Cannabis Use Disorder Have Lower Verbal IQ But No Other Cognitive Deficits
Young adults with cannabis use disorder showed significantly lower verbal IQ (d = 0.86) but no deficits in executive function, working memory, attention, or episodic memory.
A single dose of THC disrupted brain network connectivity in young adult cannabis users
Double-blind study of 33 occasional users found a single THC dose reduced resting-state brain connectivity across corticostriatal, sensory, and interoceptive networks.
THC-CBD Combination Did Not Help Alzheimer's Symptoms in Mice
Three weeks of THC-CBD treatment did not improve Alzheimer's-related deficits in transgenic mice and produced genotype-dependent effects on anxiety.
THC Had Mixed Cognitive Effects in Rats With HIV-Like Disease
THC improved learning but worsened decision-making in HIV model rats, with effects specific to the disease model and not seen in healthy controls.
What Research Says About Prenatal Cannabis Exposure and Child Brain Development
Review of prenatal cannabis exposure research found consistent links to higher ADHD risk in children, while effects on cognition, autism, and learning remained inconclusive.
Genetic Evidence Links Substance Use to Faster Biological Aging
Genomic analysis found genetic predisposition to tobacco and alcohol use causally accelerated biological aging, with mixed but suggestive evidence for cannabis use disorder.
A Brain Chemical Linked to Schizophrenia Made THC's Impairing Effects Worse in Mice
Kynurenine, a metabolite elevated in schizophrenia, amplified THC-induced motor impairment and behavioral effects in mice, possibly by raising THC blood levels.
CBD Reversed More Than 75% of Alzheimer's-Related Molecular Changes in Mice
Daily CBD reversed more than 75% of over 1,000 Alzheimer's-related molecular changes in a mouse model, affecting pathways from inflammation to synaptic plasticity.
Cannabis Users Had Lower Brain Synaptic Density in Early Psychosis PET Scans
PET imaging of 49 participants found reduced brain synaptic density in early psychosis and high-risk states, with cannabis users showing additional reductions linked to worse negative symptoms.
A Very Low Dose of CBD Reversed Stress-Related Brain Changes in Mice
A very low dose of CBD (1 mg/kg) partially reversed stress-induced behavioral changes in mice and completely restored mature synapse formation in the prefrontal cortex.
Heavy Cannabis Use Did Not Impair Basic Motor Function on Brain Scans
Brain imaging of 23 cannabis users and 6 controls found no differences in motor cortex activation between heavy, moderate, light users and non-users during motor tasks.
Cannabis Use Disorder Altered How the Brain Weighs Effort Against Reward on fMRI
fMRI study found people with cannabis use disorder had reduced prefrontal activity when evaluating effort/reward but increased posterior cortical activity during integration, despite similar behavioral choices.
A Single Dose of THC Impaired Cognition But Did Not Worsen Psychosis in People With Schizophrenia
Controlled trial of 130 participants found single-dose THC impaired cognition but did not worsen psychosis in people with schizophrenia and cannabis use disorder, though higher THC blood levels predicted worse negative symptoms.
Prenatal Cannabis Vapor Exposure Altered Brain Synapses and Memory in Rat Offspring
Vaporized high-potency cannabis during rat pregnancy altered hippocampal synapse structure, reduced CB1 receptors, increased neural excitability, and caused lasting memory deficits in offspring of both sexes.
Adolescent THC Redirected Dopamine Wiring in Male Mice But Not Females
Adolescent THC rerouted dopamine axon growth from the medial to the orbitofrontal prefrontal cortex in male mice, altering impulse control, while females were protected by different molecular responses.
Prenatal THC and maternal infection each impaired offspring cognition through different cannabinoid receptors in mice
Mouse study found prenatal THC impaired cognition through CB1 receptors while maternal immune activation worked through CB2 receptors, with the surprising finding that combining both exposures cancelled cognitive deficits.
Cannabis users over 45 reported more memory and thinking problems than non-users
Analysis of over 100,000 US adults aged 45+ found past-month marijuana users reported more subjective cognitive decline, with a dose-response relationship between use frequency and cognitive complaints.
Vaporized THC suppressed dopamine receptor genes in mouse hippocampus, with most changes recovering within 14 days
Single vaporized THC exposure suppressed hippocampal dopamine receptor genes and upregulated glutamate genes in mice, with most recovering within 14 days except persistent Adcy5 downregulation.
Babies Exposed to Cannabis in the Womb Had Smaller Brain Volume in Their First Month of Life
Neonatal MRI found lower total brain volume in infants exposed to cannabis in utero — in a carefully controlled study excluding alcohol, tobacco, and other drug exposure.
Genetic Risk for Cannabis Use Disorder Shows Up as Impulsivity and Brain Changes by Age 14
European longitudinal study finds genetic risk for cannabis use disorder is associated with impulsivity, novelty seeking, and white matter brain changes as early as age 14.
Low-Dose THC-CBD Extract Showed Cognitive Benefit in 26-Week Alzheimer's Trial
Longest cannabinoid trial in Alzheimer's: 26 weeks of very low-dose THC-CBD extract showed significantly higher cognitive scores vs placebo.
Cannabinoids shaped brain activity and new neuron growth in zebrafish
In zebrafish, CB1 cannabinoid receptors maintained excitatory brain activity in cognitive regions, while cannabinoid exposure reduced neural stem cell proliferation but increased the survival and integration of newly born neurons.
Cannabis use leaves a distinct DNA methylation signature in people with first-episode psychosis
A meta-analysis of 682 participants found cannabis use was associated with specific DNA methylation changes at immune and mitochondrial genes, independent of tobacco, with evidence that psychosis status may modify how cannabis affects the epigenome.
Older adults showed selective cognitive effects after smoking cannabis in naturalistic lab study
A crossover study of 31 adults aged 65-78 found smoking cannabis impaired trail-making performance but not most other cognitive tests, with blood THC levels poorly predicting cognitive effects in this age group.
Low-dose cannabis edibles impaired verbal memory but not other cognitive functions in regular users
A lab study of 22 regular users found cannabis edibles (mean 7.3 mg THC) impaired verbal memory but left executive function and visual attention intact, with blood THC levels failing to predict cognitive effects.
Peripregnancy cannabis use linked to behavioral problems in children with autism symptoms but not in other children
A study of over 6,000 children found that maternal cannabis use around pregnancy was linked to behavioral problems specifically in children with autism symptoms, suggesting that neurodevelopmental vulnerability may modify the effects of prenatal cannabis exposure.
High-fat/high-sugar diet impaired memory through overactivation of the brain's endocannabinoid system
A high-fat/high-sugar diet impaired mouse memory by overactivating the hippocampal endocannabinoid system and mTOR pathway, with CB1 receptor blockade or mTOR inhibition rescuing the memory deficits.
Scientists discovered a new form of brain signaling where cannabinoid and acetylcholine systems work together
Scientists discovered muscarinic cannabinoid suppression of excitation (MCSE), a new form of brain signaling where simultaneous muscarinic and cannabinoid receptor activation produces a precise ~10-minute inhibition of excitatory transmission.
THC impairs movement by shifting the brain's excitation-inhibition balance in the prefrontal cortex
Mouse study found THC impairs movement by increasing inhibitory neuron activity in the prefrontal cortex and paradoxically triggering the brain's own endocannabinoid release during movement.
Environmental Risk Factors Linked to Cognitive Decline at First Psychosis Episode
First-episode psychosis patients who showed cognitive deterioration had higher cannabis exposure and environmental risk scores than those who maintained cognitive function.
Blood Markers of the Endocannabinoid System Differed in Substance Use Disorder With and Without ADHD
Blood levels of endocannabinoid-related molecules differed in substance use disorder patients, with distinct patterns when ADHD was also present.
Lifelong Diet Composition Shaped How Adolescent THC Exposure Affected Adult Rat Behavior
Lifelong dietary fatty acid composition influenced adult rat behavior and modified adolescent THC effects on anxiety and impulsivity.
Cannabis Users Showed Brain Network Patterns Associated With Younger Brains in UK Biobank Study
UK Biobank analysis of 25,000+ people found cannabis users had brain network patterns resembling younger brains and better cognitive performance.
Cannabis plus opioid co-dependence worsens cognitive impairment beyond opioids alone
Cannabis dependence on top of opioid dependence worsened executive function and working memory deficits, though cannabis use without dependence did not add to cognitive impairment.
CBD Improved Memory and Reduced Anxiety in an Alzheimer's Mouse Model
Alzheimer's model mice given daily CBD for two months showed improved memory, less anxiety, and reduced brain oxidative stress.
What Happens to Your Memory When You Mix Weed and Alcohol?
Mixing legal-market cannabis with alcohol reduced word recall by about one word per trial—but only for men, not women.
Heavy Lifetime Cannabis Use Linked to Lower Brain Activity During Memory Tasks
Brain imaging of 1,003 young adults found heavy lifetime cannabis users had significantly lower brain activation during working memory tasks.
Lifetime Cannabis Use Linked to Larger Brain Volumes and Better Cognition in Middle-Aged and Older Adults
UK Biobank data from adults aged 40-70 found lifetime cannabis use associated with larger brain volumes in key regions and better cognitive performance.
Genetic Analysis Suggests Cannabis Use May Increase Risk of Parkinson's Disease and ADHD in Women
Mendelian randomization study using genetic data found potential causal links between cannabis use and increased risk of Parkinson's disease and ADHD in women.
Depression and Cannabis Use May Share Brain Reward Processing Deficits, But Evidence Is Inconsistent
Systematic review found depression and cannabis use share brain reward processing regions but no consistent biomarkers, with cannabis amotivation vastly understudied (only 2 studies).
What Every Parent Should Know About Teens and Cannabis in 2025
Teen cannabis use has held steady despite legalization, but ER visits, child ingestions, and product potency have all increased—changing the risk landscape.
Adolescent THC Exposure Caused Lasting Brain and Motivation Problems in Monkeys
Six months of daily THC during adolescence in monkeys produced persistent brain connectivity changes in reward regions and lasting motivational deficits into adulthood.
Cannabis Users with MS Show Poorer Processing Speed and Working Memory
Among 847 people with MS, the 30% who used cannabis performed significantly worse on processing speed and working memory tests, even after adjusting for disease severity and other factors.
93% of Long-Term Medical Cannabis Users Say It Works for Chronic Musculoskeletal Pain
A prospective survey of 129 long-term medical cannabis users for chronic musculoskeletal pain found 93% reported symptom improvement, 72% had no cognitive effects, and 80% maintained stable usage over time.
Meta-Analysis Finds Cannabis Users Have Lower Levels of Key Brain Chemicals
First meta-analysis of brain spectroscopy studies found cannabis users had lower GABA and neural health markers in the anterior cingulate cortex, and lower glutamate in the basal ganglia.
Alpha-Pinene Does Not Counteract THC-Induced Memory Impairment in Humans
A double-blind crossover trial found alpha-pinene at three doses did not counteract any THC effects in 19 adults.
Childhood Externalizing Disorders Strongly Predict Problematic Cannabis Use Patterns in Adolescence
In 6,049 participants from the ALSPAC cohort, childhood externalizing disorders at age 10 predicted multiple problematic cannabis use trajectories from ages 15-24.
How Cannabis Reshapes Brain Communication—and Why Chronic Users Are Different
Cannabis disrupted brain connectivity patterns in all users, but chronic users showed persistent network changes even when sober—suggesting lasting brain adaptation.
Recreational Drug Users Had More Difficulty Recalling Personal Memories
A lab study found recreational drug users, including cannabis users, recalled fewer specific personal memories than non-users, even after accounting for sleep, health, and alcohol.
We Still Don't Know Enough About THC to Set Fair Driving Laws
Cannabis driving laws are being set without adequate science—we need comprehensive THC pharmacokinetic data to connect blood levels to actual impairment.
Heavy Cannabis Use Was Linked to Thinning of a Brain Region Involved in Decision-Making Over Three Years
A three-year brain imaging study found heavy cannabis users developed significant thinning in a brain region crucial for decision-making, with greater thinning linked to more severe use patterns.
Scientists Found the Specific Brain Cells Behind THC's Cognitive Impairment and a Way to Prevent It
Researchers identified a specific group of astrocytes that drive THC-induced cognitive impairment and showed that dampening their overactivity prevents spatial learning deficits in mice.
A Traditional Thai Medicine Containing Cannabis Protected Against Stress-Induced Memory Problems in Mice
Traditional Thai medicine containing cannabis leaves reversed stress-induced cognitive impairment in mice through antioxidant pathways, with THC and THCA identified as active compounds.
Limited Evidence for Sex Differences in How Cannabis Acutely Affects Thinking
Systematic review of 29 studies found limited evidence for sex differences in acute cannabis cognitive effects, though females showed greater impairment in the few studies that found differences.
Can Cannabinoids Help Treat ADHD? A Review of the Emerging Evidence
Review examines the cannabis-ADHD connection, finding elevated cannabis use risk in ADHD and early evidence that CBD may have therapeutic potential through dopamine pathway modulation.
Missouri College Students More Open to Cannabis After Legalization
Missouri college students showed more positive cannabis attitudes and higher use intentions after the state legalized recreational cannabis.
More Frequent Cannabis Use Linked to More Gambling Behavior
Study finds a link between more frequent cannabis use and greater gambling involvement, suggesting shared risk factors.
Cannabis Impairs Driving in Simulator Study, Even When Users Feel Fine
Randomized simulator trial finds cannabis impairs driving performance even when users feel capable, highlighting a dangerous perception gap.
Long-Term Cannabis Use Leaves Marks on DNA, Dunedin Study Finds
The Dunedin Study found long-term cannabis users have distinct DNA methylation patterns, suggesting lasting epigenetic effects from decades of use.
Daily Cannabis Use Amplifies Cognitive Problems in People With Chronic Conditions
National survey of nearly 95,000 adults finds daily cannabis use associated with 145% higher cognitive difficulty in those with chronic conditions and 183% higher in those without.
Medicinal Cannabis Users Drive More Cautiously After THC, but Can't Judge Their Own Impairment
Medicinal cannabis users showed no hazard perception decline after oral THC and drove more cautiously, but none could accurately judge their own impairment level.
Inattentive and Hyperactive ADHD Create Different Cannabis Problem Pathways
Study reveals two distinct pathways from ADHD to cannabis problems: inattention directly causes functional impairment, while hyperactivity drives heavier consumption leading to dependence.
Prenatal Cocaine Exposure Leads to More Marijuana Use by Age 21, Through Cognitive Pathways
Birth cohort study finds prenatal cocaine exposure leads to more marijuana use by age 21 through a chain of executive function deficits at 12 and substance use at 15.
Regular Cannabis Use Linked to Better Decision-Making in People With Bipolar Disorder
Surprising finding: regular cannabis use in bipolar disorder was linked to decision-making and functioning on par with healthy non-users, while cannabis impaired healthy participants.
Seven Months of CBD Improved Memory and Reduced Brain Inflammation in Aging Mice
Aging mice given oral CBD for 7 months showed reduced brain inflammation and improved cognitive function across multiple brain region-specific tasks.
THC Destabilizes Brain Cell Scaffolding, Offering a Mechanism for Memory Effects
Lab study reveals THC directly destabilizes microtubules by altering tubulin protein structure, proposing a new molecular mechanism for cannabis-related memory impairment.
Recent Cannabis Use Doesn't Worsen Brain Wave Abnormalities in Psychosis
EEG study of 93 psychosis patients finds brain activity abnormalities are equally present regardless of recent cannabis use, suggesting they are core features of psychosis, not cannabis effects.
Cannabinoid Drug Prevented Memory Loss in a Rat Dementia Model
Low-dose cannabinoid treatment prevented spatial memory loss in rats by indirectly boosting the cholinergic system through cannabinoid receptor activation in cortical regions.
Does Cannabis Affect Thinking in Older Adults? A Study of 540 People Says Mostly No
Among 540 older adults across the dementia spectrum, moderate cannabis use was not associated with worse cognitive test performance—though problem use may differ.
Cannabis Affects the Brain Differently Depending on Your Age
A narrative review of cannabis effects across the lifespan found that prenatal and adolescent exposure carries the highest neurological risk, while cannabis use among older adults is rising fastest with the least risk awareness.
Older Adults Hospitalized for Cannabis Use Faced Higher Dementia Risk
An Ontario study of 6.1 million adults over 45 found that those with emergency visits for cannabis use had 1.72x higher dementia risk than the general population, though lower risk than those with alcohol-related visits.
What Does the Research Say About Cannabis, Aging, and Longevity?
A systematic review of 18 studies found preclinical promise for cannabinoids in supporting healthy aging, but noted that human evidence remains too sparse to draw definitive conclusions.
A CBD-CBC Combination Best Reversed Sleep Deprivation Damage in Mice
Among multiple cannabinoid treatments tested in sleep-deprived mice, a CBD+CBC combination was the most effective at reversing memory impairment, depression, and brain inflammation.
84 of 99 Brain Imaging Studies Found Cannabis Changes Young Brains
A scoping review of 99 neuroimaging studies found that 85% detected differences in brain structure, function, or chemistry in cannabis users aged 14-25, though research quality was generally low.
Cannabis Impairs Attention While Nicotine Enhances It, But Both Harm Developing Brains
A review found cannabis impairs attention while nicotine enhances it in adults, but both substances harm attention development when exposure occurs prenatally.
A Synthetic Cannabinoid Rescued Memory Deficits in Alzheimer's Mice
A synthetic cannabinoid rescued memory deficits, reduced brain inflammation, and restored glucose metabolism in Alzheimer's mice without increasing anxiety.
The Body's Own Cannabis System May Play a Role in ADHD
A review of 13 studies found emerging evidence that the endocannabinoid system may contribute to ADHD, with preclinical links between altered cannabinoid signaling and hyperactivity.
THC Slowed Thinking More in Lighter Cannabis Users Than Heavier Ones
Placebo-controlled experiment found THC impaired cognitive efficiency more in lighter users than heavier ones, supporting the role of tolerance in moderating acute effects.
Among Daily Cannabis Users, Risk-Seekers Had More Negative Consequences
Small study of 51 daily cannabis users found risk-seeking predicted more negative consequences, while acting on positive emotions predicted fewer.
Does CBD Protect Your Memory When You Use THC?
THC impaired verbal memory as expected, but adding CBD in a 1:1 ratio didn't protect against the effect—challenging a popular harm reduction claim.
CBD Reversed Autism-Related Behavioral Problems in a Mouse Model
Single-dose CBD reversed social deficits, repetitive behaviors, and cognitive problems in a mouse autism model, though it did not affect stereotyped movements.
Activating Cannabinoid Receptors Worsened ADHD-Like Behaviors in Adolescent Rats, Especially Females
Rat study found activating cannabinoid receptors during adolescence worsened ADHD-like hyperactivity and risk-taking, with stronger effects in females.
Cannabinoid Receptor Activation Reduced Impulsivity in Highly Impulsive Rats, With Lasting Effects
Cannabinoid receptor activation reduced impulsive decision-making specifically in highly impulsive rats, with effects lasting at least two weeks after the last dose.
Caregivers Reported Wide-Ranging Improvements Beyond Seizure Control from CBD in Severe Epilepsy
Survey of 243 caregivers found CBD with clobazam improved seizures (87%), cognition (84%), and communication (76-81%) in patients with severe epilepsy.
CBD Reduced Behavioral Symptoms of Vascular Dementia in a Small Trial Without Affecting Cognition
Small RCT found CBD 300 mg/day significantly reduced behavioral symptoms of vascular dementia after 4 weeks without cognitive or functional side effects.
When During Pregnancy THC Exposure Happens May Determine the Brain Effects
Rat study found THC exposure at different pregnancy timepoints produced different effects on brain immune cells and social behavior—timing matters, not just exposure.
Cannabis Use Disorder in MS Patients Is Common but Treatment Options Are Nearly Nonexistent
Pilot study found strong demand for cannabis use disorder treatment among MS patients, with over half using cannabis and up to 20% at risk for use disorder.
Brain Stimulation via Telehealth Reduced Cannabis Use and Withdrawal in Women with MS
Pilot RCT found telehealth brain stimulation with mindfulness reduced cannabis use by 1.4 days/week and significantly decreased withdrawal in women with MS.
Prenatal Cannabis Exposure Was Not Linked to Developmental Delays at Age 2
Large prospective cohort found no significant link between prenatal cannabis use and child cognitive, motor, or language development at age 2, with an unexpected positive language association in girls.
People With Cannabis Use Disorder Did Not Show Consistent Attentional Bias Toward Cannabis Images
Study found no consistent attentional bias toward cannabis images in people with moderate-to-severe cannabis use disorder, challenging a core theory of addiction.
CBD Improved Memory and Reduced Alzheimer's Markers in Mouse Model
CBD improved spatial memory and simultaneously reduced amyloid plaques, tau tangles, neuroinflammation, and oxidative stress in an Alzheimer's mouse model.
Cannabis and Schizophrenia: Risk Factor, Treatment, or Both?
A rigorous review of 8 studies found THC linked to increased psychosis risk while CBD showed potential therapeutic effects—the two cannabinoids may work in opposite directions.
Adolescent THC Exposure Created Lasting Tolerance to Cannabis Effects in Adult Monkeys
Primate study found that adolescent THC exposure created lasting tolerance to cannabis cognitive effects that persisted at least a year after stopping, with higher doses needed to impair attention.
Activating Cannabis Receptors During Adolescence Permanently Alters Brain Rhythms
Rats exposed to cannabinoid receptor activation during adolescence showed lasting disruptions in hippocampal brain rhythms critical for memory—even in adulthood.
Adolescent Cannabis Receptor Activation Disrupts Adult Brain Rhythms (Preprint)
Preprint companion to RTHC-00197 with additional detail: sex-balanced cohorts and extended testing confirm lasting hippocampal theta disruptions from adolescent cannabinoid exposure.
Brain Science App Reduced Cannabis Use and Improved Decision-Making in College Students
Pilot study found a neuroscience-based mobile app reduced cannabis use and improved executive function, metacognition, and decision-making in 68 college students after just four sessions.
The Road From Early Warning Signs to Full Psychosis—and Where Cannabis Fits
A review of 60 studies mapped psychosis development: early symptoms are mostly depression and anxiety, with cannabis conferring 4-fold risk (10-fold with genetic vulnerability).
High-Intensity Exercise Did Not Repair Brain Changes From Cannabis Use Disorder
Rigorous RCT found 12 weeks of high-intensity exercise did not improve brain structure or mental health in cannabis use disorder, though 80% of participants completed the program and exercise reduced cravings.
Cannabis Increases Spontaneous Mind-Wandering and Impairs the Ability to Control It
Controlled study found cannabis significantly increases spontaneous mind-wandering and impairs the ability to regulate attention in regular users.
Cannabis Users Show Deficits in Reading Emotions But Normal Levels of Emotional Empathy
Cannabis users under the influence showed impaired emotion recognition (especially for positive stimuli) but maintained emotional empathy, with specifically dampened reactions to negative stimuli.
Four Weeks Without Cannabis Improved Adolescent Brain Function in a Randomized Trial
Randomized trial of 238 adolescents found that four weeks of cannabis abstinence improved inhibitory control compared to continued use, with abstinent users performing similarly to non-users by the end of the study.
CBD Shows Inconsistent Effects on Cognition Across 36 Randomized Trials
Review of 36 randomized controlled trials found CBD had variable effects on cognition: some anxiety reduction at 300-400 mg, minor Parkinson's benefits at 75-300 mg, but minimal cognitive effects in schizophrenia and substance use disorders.
Cannabis Users with ADHD Reported Fewer Symptoms After Acute Use but Showed Cognitive Differences
Study of 104 adults found cannabis users with ADHD reported subjective symptom improvement after acute use, but chronic cannabis use was associated with objective cognitive differences regardless of ADHD status.
UK Biobank Study Finds Past Cannabis Use Linked to Better Cognitive Performance in Older Adults
UK Biobank study of 67,713 older adults found lifetime cannabis users performed better across five cognitive domains, though longer use duration was linked to faster processing speed decline.
How THC Disrupts Spatial Memory by Silencing GABA Neurons in the Prefrontal Cortex
CB1 activation in the prefrontal cortex impaired spatial memory formation in mice by reducing GABA release—a specific mechanism explaining THC's memory effects.
The Largest Study Yet on How Adolescent Cannabis Affects Brain Development Over Time
In 11,036 adolescents, cannabis use onset altered cognitive development trajectories—and hair testing showed THC and CBD had different effects on cognition.
How CBD Might Treat Schizophrenia: Two Mechanisms Identified
CBD reduced schizophrenia-like symptoms in animals through two pathways: reducing neuroinflammation and modulating serotonin-MAPK signaling.
Cannabis During Pregnancy May Delay a Critical Switch in How Baby Brains Wire Themselves
Prenatal cannabis exposure may delay GABA's developmental switch from excitatory to inhibitory—disrupting the precise timing that guides how the fetal brain wires itself.
Cannabis May Actually Improve Working Memory in Aging Brains
Preclinical study finding chronic oral THC enhances working memory in aged rats without affecting young adults, suggesting cannabis may help age-related cognitive decline.
Prenatal THC Changed the Chemical Composition of Offspring's Brain Tissue
Advanced imaging revealed prenatal THC reduced copper in offspring brain tissue and altered neurochemistry in emotion-processing circuits—molecular fingerprints of exposure.
Teen Marijuana Use Alters Brain Network Connections But Not Cognitive Performance
Study of typically developing youth finds marijuana use alters brain network connectivity without cognitive deficits, while alcohol shows cognitive associations without brain connectivity changes.
Long-Term Cannabis Users Show No Cognitive Deficits When Abstinent — But Distinct Personality Traits
Study finds chronic cannabis users matched for IQ and education show no cognitive deficits after abstinence — personality traits like novelty seeking, not brain function, distinguish them from non-users.
Cannabis Use Doesn't Appear to Worsen Memory Problems in People Living with HIV
Study of 307 people with HIV finds cannabis use — even regular use — is not associated with worse prospective memory, with dual-motivation users trending toward better performance.
CBD Changed Brain Waves and Improved Cognition in Boys With Severe Autism
In a rigorous trial, pharmaceutical CBD altered brain waves and improved cognitive abilities in boys with severe autism—with blood CBD levels predicting the brain changes.
Cannabis Impairs Nearly Every Type of Memory, Not Just Verbal Recall
Gold-standard placebo-controlled trial of 120 people found cannabis impairs 10 of 13 memory types tested — including everyday memory like remembering plans and event sequences — with no difference between moderate and high doses.
History of Cannabis Smoking Linked to Memory Complaints in Older Women
Large prospective study of 15,378 women over 65 found past cannabis smoking linked to 27-30% higher odds of cognitive complaints, with regular smokers at 61% higher risk — a dose-dependent association persisting decades after use.
Prenatal Cannabis Exposure Linked to Altered Brain Connectivity in Children
Large-scale ABCD Study analysis found prenatal cannabis exposure associated with altered brain network connectivity, cognitive differences, and mental health symptoms in children.
CBD Improved Memory After Brain Injury by Activating a Novel Protective Pathway
Preclinical study discovers CBD improves cognition after traumatic brain injury through a novel mechanism — directly binding the SET protein to activate a neuroprotective pathway previously unknown in cannabinoid research.
Psychosis and Cannabis: Rethink “Users Always Think Worse”
In one inpatient psychosis sample, cannabis users had higher MoCA scores than non-users.
Higher Working Memory May Help Cannabis Reduce Alcohol Cravings
A crossover trial found that high-potency cannabis reduced alcohol cravings only in people with higher working memory, suggesting cognitive capacity determines who benefits from cannabis as an alcohol substitute.
Cannabis Use Not Linked to Cognitive Decline or Dementia Risk in Older Adults
Two large cohorts (250,000+ participants) and genetic analyses find no link between cannabis use and cognitive decline or dementia risk in older adults.
Smarter Kids Try Cannabis Earlier — But Positive Expectations Explain Why
ABCD Study data shows higher cognitive ability at ages 9-10 predicts cannabis use by 13-14, but positive cannabis expectations explain 73% of the effect — a clear prevention target.
Prenatal THC Activated Schizophrenia-Linked Genes in Rat Placentas
Prenatal THC in rats altered placental expression of genes previously linked to schizophrenia in human studies, with sex-specific effects and fetal growth restriction.
High doses of CBG impaired sustained attention in female rats but not males, despite marketing claims of cognitive enhancement
High-dose CBG impaired sustained attention in female rats but not males, contradicting marketing claims of cognitive enhancement.
Finding the Right Antipsychotic Dose After Cannabis-Induced Psychosis
Swedish nationwide study found moderate antipsychotic doses most effective for preventing psychotic relapse after cannabis-induced psychosis — higher doses added no benefit.
Ultra-low-dose THC given before Alzheimer symptoms appeared reduced brain inflammation in mice, with different brain regions affected by sex
Monthly ultra-low-dose THC prevented cognitive decline in Alzheimer mice, with sex-specific anti-inflammatory patterns.
Daily CBD did not rescue behavior or brain volume in an aggressive Alzheimer mouse model, but did reduce microglial reactivity
Daily CBD in Alzheimer mice reduced brain immune cell reactivity but did not improve cognition, behavior, or brain volume.
Why Cannabis May Be Especially Dangerous for Older Drivers
Review argues that older adults may be more impaired by cannabis while driving due to age-related changes in metabolism, cognition, and the endocannabinoid system.
Prenatal Cannabis Plus Teenage Stress Increased Risk-Taking in Mice
Mouse study shows prenatal cannabis exposure combined with adolescent stress increased risk-taking behavior, while neither factor alone had this effect.
Long-Term Cannabis Use Linked to Impaired Automatic Movement Learning
Study found longer cannabis use history linked to weaker automatic movement learning and elevated resting brain activity, suggesting altered baseline neural dynamics.
THC Drug Dronabinol Safely Reduced Agitation in Alzheimer's Patients in Clinical Trial
Multicenter RCT finds dronabinol (THC) safely and effectively reduces Alzheimer's agitation over 3 weeks with a medium effect size and no cognitive decline.
CBD-THC Mixture Helped Brain Immune Cells Clear Alzheimer's Plaques in Mice
CBD:THC (99:1) mixture enhanced microglial clearance of Alzheimer's plaques in mice but also worsened anxiety and depression behaviors, highlighting the therapeutic trade-off.
Three-quarters of adults with ADHD have tried cannabis, with daily users showing higher rates of anxiety and addiction
A survey of 900 adults with ADHD found 75% had used cannabis, with daily users showing significantly higher rates of cannabis use disorder (62%), anxiety (70%), and worsened inattention compared to non-daily users.
Even monthly cannabis use was linked to worse academic performance and self-regulation in a study of over 162,000 US teens
Study of 162,532 US teens found dose-dependent links between cannabis use frequency and worse academic performance, self-regulation, and emotional states, even at monthly use levels, with younger teens more vulnerable.
THC produced the same physiological effects in HIV-model rats and healthy controls without worsening HIV-related motivation deficits
THC produced consistent physiological effects in HIV-model rats without worsening motivation deficits, and chronic use showed tolerance to acute motivational impacts.
Prenatal Cannabis and Tobacco Exposure Linked to Children's Behavior Problems and Altered Brain Networks
ABCD Study found prenatal tobacco and marijuana exposure linked to children's behavior problems, with tobacco specifically altering connectivity between attention and default mode brain networks.
A Single THC Dose in Newborn Rats Caused Memory Problems in Females But Not Males
Single neonatal THC dose caused lasting spatial memory deficits in female rats but not males, with altered dendritic structure in both sexes — revealing stark sex-specific vulnerability.
Frequent cannabis use was linked to lower levels of Klotho, a protein associated with healthy aging, in middle-aged adults
NHANES analysis of nearly 6,000 middle-aged adults found frequent cannabis use linked to significantly lower Klotho, an aging biomarker, with a dose-dependent relationship.
About 1 in 9 U.S. adolescents use marijuana, and higher use tracks with more missed school and lower grades
National survey data showed 11.4% of U.S. teens ages 12-17 use cannabis, with higher use linked to more missed school and lower grades.
Adolescent cannabis use was linked to cortical thinning, especially in males, and some brain differences existed before use began
Longitudinal brain imaging of 136 teens found cannabis use linked to cortical thinning (especially in males), while pre-existing brain differences also predicted who would use cannabis.
People who use both cannabis and tobacco together may actually perform better cognitively than those who use either substance alone
Systematic review of 39 studies found cannabis and tobacco co-users showed similar cognitive and brain function to non-users, suggesting the substances may offset each other's impairments.