Browse more cannabis research, findings, methods, and limitations.
In 112 rats, prior nicotine exposure altered THC brain effects depending on age and sex: adult males showed reduced THC response while adolescent females showed potentiated effects.
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 reversed memory deficits from brain inflammation in rats by modulating CB1/CB2 receptors and inflammatory enzymes in the hippocampus.
Review of pharmaceutical CBD for epilepsy synthesized 4 pivotal RCTs showing significant seizure reduction in DS and LGS, with important drug interactions via CYP2C19.
Review plus clinical experience found early evidence that cannabis and CBD may help ASD symptoms and comorbidities, but large controlled trials are needed.
Prospective study of 265 early psychosis patients found starting cannabis before age 15 was associated with 4.5 times higher odds of violent behavior.
First CSF study found significantly elevated endocannabinoids (AEA, 2-AG) in Tourette syndrome patients, with 2-AG correlating to ADHD severity.
Review found CB1 receptor remains a promising obesity target despite rimonabant failure, with peripheral-only blockers and neutral antagonists as safer alternatives.
Landmark GAP study of 410 first-episode psychosis patients found 25% of new cases attributable to high-potency cannabis, with genetic and environmental factors acting together.
Meta-analysis of 50 studies (40,783 people) found 34% of cannabis-induced psychosis cases transitioned to schizophrenia, the highest rate among all substances.
Three small trials (93 subjects) showed cannabis improved Crohn disease symptoms but mostly did not reduce inflammation markers, raising questions about symptomatic versus disease-modifying effects.
Illinois outbreak linked synthetic cannabinoids contaminated with rat poison (brodifacoum) to 174 severe bleeding cases and 5 deaths in 2018.
Time-series analysis found Uruguay cannabis legalization associated with 52% increase in car driver fatalities, concentrated in urban Montevideo, with no effect on motorcyclists.
Study of 99 cannabis treatment seekers found ADHD prevalence of 34-46%, far exceeding general population rates, suggesting routine ADHD screening should be standard.
Study of 910 students found cannabis use predicted psychosis-like traits, with aberrant salience (abnormal importance assignment) mediating the relationship.
Systematic review of 9 studies (7,222 patients) found 64-75% opioid dose reduction with medical cannabis for chronic pain, but all studies had high bias risk.
Danish study of 21,066 schizophrenia patients found cannabis use disorders associated with 16% lower risk of gut-brain disorders and 30% lower IBD risk, with no such association in healthy controls.
Systematic review found only 2 eligible studies on cannabis exposure during breastfeeding, with conflicting results on infant development, exposing a critical evidence gap.
Study of 431 chronic pain patients found emotion dysregulation explained the link between cannabis use problems and anxiety, depression, and suicidal ideation.
Study of 20 drivers found cannabis impaired visual acuity, contrast sensitivity, and depth perception, with visual deficits directly correlated with worse driving performance.
AHA first scientific statement on cannabis concluded cardiovascular harms (arrhythmia, MI, stroke) outweigh uncertain benefits, calling for Schedule 1 reclassification to enable research.
Analysis of 27M pediatric hospitalizations found cannabis use disorder 68% more common in prescription opioid overdose cases, alongside high rates of mood disorders.
Georgia expanded access program found sustained seizure reduction over 36 months in 45 children with treatment-resistant epilepsy on CBD, with adverse events decreasing over time.
Study of 1M+ schizophrenia inpatients found cannabis use disorders independently associated with 38% higher medication non-compliance after adjustments.
Review of 62 published cases found marijuana-linked heart attacks averaged age 27.7, with 37% having normal coronary arteries and 7 deaths.
Systematic review found 10 of 12 studies support a cannabis-psychosis link, with THC identified as the primary risk and CBD as potentially therapeutic.
Systematic review found frequent cannabis users can exceed legal THC driving limits (2 or 5 ng/mL) after days of abstinence, challenging per se laws.
Study of 1,000 adults found psychosis warnings on cannabis packaging were most educational and best for discouraging youth use; any warning increased perceived harm.
Review describes cannabis hyperemesis syndrome as a gut-brain disorder caused by CB1 receptor changes in chronic users, with hot bathing, capsaicin, and haloperidol as management options.
Researchers discovered CBD inhibits methionine synthesis through one-carbon metabolism, a new mechanism validated in Dravet syndrome mouse and rat seizure models.
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.
In 3 infants with rare KCNT1 epilepsy, CBD showed limited benefit: 2 had no response, 1 had reduced seizure intensity and possible developmental progress.
Prospective study of 2,327 college students found dual cigarette/e-cigarette use predicted marijuana vaping initiation, while vape shop social networks predicted escalation.
Mouse study found cannabinoid receptor compounds enhanced antidepressant effects of tianeptine and agomelatine without changing brain drug levels, suggesting true synergy.
Mouse study found both CB2 agonist and inverse agonist enhanced three classes of conventional antidepressants without changing brain drug levels.
A 15-year-old with autism showed unexpected improvements in core social deficits, anxiety, and sleep on low-dose CBD extract originally prescribed for epilepsy.
A 9-year-old with Lennox-Gastaut syndrome achieved complete seizure control and dramatic EEG normalization on CBD, an improvement not previously described.
Review found CB1 worsens and CB2 protects heart inflammation during ischemia, while cannabis use may trigger arrhythmias and metabolic dysfunction.
In vitro study found pure CBD matched or exceeded commercial CBD oils at reducing cancer cell viability, with some oils appearing to protect cancer cells.
Rat study found CBD disrupted fear memory consolidation within a 1-hour window, using CB1/CB2 receptors immediately but PPARγ receptors at the 1-hour mark.
Thirteen-year study of people who inject drugs found daily cannabis use associated with 26% faster opioid injection cessation, with no increase in relapse risk.
Analysis of 410,138 NSDUH respondents found cannabis exposure tracked with all four mental health indices, with serious mental illness doubling as use increased and legalization linked to 12.91% attributable fraction.
Hemp seed oil improved immune cell membrane composition and inflammatory markers in an MS mouse model, with additive benefits alongside rapamycin.
Review proposes CB2 receptors as drug targets for HIV brain inflammation, noting cannabis-using HIV patients have lower inflammatory monocyte levels.
Eleven-year study of 1,457 Hispanic youth found high school discrimination predicted marijuana use initiation and continuation into emerging adulthood.
Systematic review found prenatal cannabis exposure may be linked to ADHD and affective symptoms in offspring, but the topic is under-researched despite common use.
Scoping review found only 8 studies on cannabis during radiation therapy, with possible benefits for anxiety and long-term symptoms but 6 of 8 at high bias risk.
Case of a long-time marijuana user who developed paranoid psychosis within one month of switching to "dabs" with up to 80% THC.
Systematic review found THC impaired facial emotion recognition in half of experiments while CBD improved it, with opposing brain activation for threatening faces.
Analysis of 709,658 drug-related healthcare visits in Florida found cannabis SUD was the lowest-cost condition, with opioids 23.4% and cocaine 9.25% more expensive.