Explore published research on psychosis, including study methods and limitations.
Two weeks of daily THC made rats hypersensitive to amphetamine's psychosis-like effects after withdrawal, supporting a biological mechanism for cannabis-associated psychosis risk.
In 232 first-episode schizophrenia patients, cannabis preceded psychosis in one-third, coincided with onset in another third, and began after symptoms in the final third, suggesting multiple pathways.
Population-based study of 232 first schizophrenia episodes finding double the rate of substance abuse compared to controls, with cannabis used by 88% of drug abusers and drug use often preceding illness onset.
Major Brain journal review finding cannabis cognitive impairments appear reversible with little evidence of brain pathology, and limited evidence for causal psychiatric illness links.
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.
Study of 357 first-episode psychosis patients found 44% met criteria for substance abuse/dependence, primarily involving cannabis and alcohol, with higher rates in younger males.
Population-based study of 133 schizophrenia patients found male cannabis users developed their first psychotic episode 6.9 years earlier than male non-users.
Comprehensive review found strong evidence linking cannabis to psychosis, supported the existence of cannabis withdrawal syndrome, and called for more rigorous research on prevention and treatment.
Review found cannabis-based MS medicines had mild side effects in trials but urged caution for psychosis-prone and pregnant patients, noting therapeutic benefits remained modest.
UK study of 152 first-episode schizophrenia patients found 68% had lifetime drug use, with cannabis independently predicting earlier psychosis onset after adjusting for other substance use.
Three-year follow-up in Aboriginal communities found cannabis use decreased overall, but persistent users had higher rates of hallucinations, suicidal thoughts, and imprisonment.
Population study of 4,815 adults found cannabis use nearly tripled the risk of developing manic symptoms over 3 years (OR 2.70), independent of psychotic symptoms and with no evidence of self-medication.
Among 757 first-episode schizophrenia cases, cannabis users and non-users showed essentially the same symptoms, arguing against a distinct "cannabis psychosis."
Cannabis extract with CBD enhanced automatic brain responses to auditory changes, while pure THC alone did not, suggesting CBD may protect cognitive processing.
Olanzapine reversed THC-induced spatial memory impairment in rats by restoring hippocampal acetylcholine levels, while haloperidol had no effect at any dose tested.
Review found limited evidence that cannabis use may worsen metabolic health in psychosis patients already at elevated cardiovascular risk, though long-term effects remain unclear.
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.
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.
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.
In 15 men, THC increased anxiety and skin conductance responses to fearful faces, while CBD reduced amygdala activation and autonomic arousal, demonstrating opposite emotional processing effects.
CBD (20 mg/kg) reversed THC-induced social withdrawal in rats at low doses, but the combination of high doses of both compounds impaired social interaction, possibly through sedation.
Among 3,459 bipolar patients followed for 12 months, cannabis users had less treatment compliance, more mania, more psychosis, and higher overall illness severity with little evidence of confounding.
A systematic review found only 7 RCTs on treating cannabis use in psychosis/depression, with preliminary evidence supporting medication treatment of the primary disorder and longer psychological interventions.
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.
Both psychosis patients and controls showed negative implicit cannabis associations, but patients had stronger explicit negative awareness. Relaxation expectancies were the strongest predictor of actual cannabis use in both groups.
A commentary argued for harm reduction through product composition changes, specifically reducing THC and increasing CBD in cannabis to lower psychosis and addiction risks.
Brief review linking cannabis use in adolescents to psychosis, depression, panic attacks, and suicidal thoughts.
In 169 first-episode psychosis patients, cannabis use was linked to earlier onset and appeared to override the COMT gene's protective delay effect.
Review of brain imaging studies found white matter abnormalities in early schizophrenia, with adolescent cannabis use having specific effects on these measures.
Socially isolated rats showed increased endocannabinoid system gene expression in brain regions relevant to schizophrenia, including higher CB1 and lower FAAH in prefrontal areas.
First-episode schizophrenia patients who used cannabis showed better attention and executive function than non-users, both initially and after one year.
Comprehensive review found recreational cannabis adverse effects were generally minor, with overall harms appearing less serious than alcohol, though vulnerable individuals faced greater risks.
Pre-illness cannabis use in 109 first-episode patients was linked to better early social skills but worse academics, and daily use predicted acute (rather than gradual) psychosis onset.
The generic EQ-5D quality measure only moderately captured quality of life in 103 schizophrenia patients with cannabis abuse, missing domains like relationships and finances.
First documented case of marijuana-induced mania in an adolescent with no prior psychiatric history.
In a small terminated trial, the CB1 antagonist rimonabant reduced anxiety and hostility in schizophrenia patients but did not produce weight loss.
Cochrane review of 18 RCTs found emerging evidence for specialized early psychosis services but inconclusive results for cannabis-specific therapy and most other interventions.
Among 109 first-episode psychosis patients, 57.8% had been previously incarcerated, with earlier cannabis use linked to incarceration history.
Brain imaging showed THC and CBD had opposite effects on auditory processing regions, with THC's disruption correlating with psychotic symptoms.
Comprehensive Mayo Clinic review of cannabis therapeutics, addiction, psychosis, and policy, noting the gap between public approval and scientific evidence.
Systematic review found first-episode psychosis and cannabis effects both increased anterior cingulate cortex activity, suggesting shared neural mechanisms.
Adolescent but not adult cannabinoid exposure in mice produced lasting schizophrenia-like deficits, linked to reduced hippocampal mGluR5 and altered endocannabinoid metabolism.
Review of Spice/K2 effects found anxiety and psychosis reports, while three cases showed cannabis-dependent users found synthetics relieved their withdrawal.
Cannabis-using first-episode schizophrenia patients had earlier psychosis onset but better cognition, with 75% quitting cannabis spontaneously over follow-up.
Schizophrenia patients with cannabis history showed better task-related brain activation and less default-mode activity at rest than non-using patients.
In the same 16 men, oral THC caused anxiety, psychotic symptoms, and sedation, while 600 mg CBD was indistinguishable from placebo.
College students with schizotypy traits and higher social anxiety used cannabis more frequently and reported more cannabis-related problems than those without social anxiety.
Brain imaging found chronic cannabis users had altered activation in social cognition regions, matching patterns seen in psychosis-risk populations.
Depression and insight measures distinguished cannabis-induced psychosis from primary psychotic disorders with 97% accuracy in hospitalized patients.
Cannabis improved verbal fluency in people with low baseline creativity while increasing psychosis-like symptoms in all users.
Meta-analysis found schizophrenia patients who used cannabis had better cognitive performance than non-using patients, suggesting a different pathway to psychosis.
Systematic review of 34 human studies found preliminary CBD benefits for anxiety, insomnia, and epilepsy, with complex THC interactions depending on delivery route.
About half of healthy men experienced psychotic symptoms from THC while half did not, with distinctly different brain activation patterns between groups.
Review found medical cannabis has the best evidence for pain and spasticity, with dizziness as the most common side effect and adolescent psychosis risk as the main safety concern.
Schizophrenia patients with cannabis abuse showed better emotional memory and more preserved prefrontal brain activity than non-using patients.
Review found adolescent cannabis use predicts anxiety, depression, and psychosis more strongly than adult use, with earlier initiation increasing risk.
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.
Male mice with BDNF deficiency became hypersensitive to cannabinoid effects on sensory gating after chronic young-adult cannabinoid exposure, with increased CB1 receptors in nucleus accumbens.
Systematic review found inconclusive evidence for cannabis effects on brain structure in schizophrenia, with no convincing pre-onset structural changes.
Cannabis use was linked to reduced cingulate cortex volume in both at-risk and first-episode psychosis patients, in a brain region rich in cannabinoid receptors.
Both healthy cannabis users and people at ultra-high risk for psychosis showed reduced P300 brain wave amplitudes, suggesting overlapping effects on information processing.
Review found about 70% of bipolar patients used cannabis, with use linked to earlier first mania and more frequent episodes, though causation remained unestablished.
Landmark review found CBD showed anticonvulsant, anxiolytic, antipsychotic, and anti-addictive properties but lacked well-powered trials, setting the stage for the clinical program that led to FDA approval.
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.
Clozapine reduced cannabis craving and insula brain activity more than risperidone in patients with schizophrenia and cannabis use disorder over 4 weeks of treatment.
Review presents evidence that CBD could serve as an antipsychotic agent through non-dopamine mechanisms, potentially augmenting standard medications and addressing metabolic and inflammatory components of schizophrenia.
Among 502 first-episode psychosis patients, cannabis users who reduced or stopped use after treatment contact showed the greatest symptom improvement at one year.
Systematic review of 122 studies found exogenous cannabinoids suppress immune function and shift Th1/Th2 balance, potentially creating latent vulnerability to psychosis, especially during adolescence.
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.
In 110 people with early psychosis and cannabis dependence, reducing cannabis was linked to lower anxiety and better functioning, but not to changes in core 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.
Brain imaging showed THC and CBD had opposite effects on connectivity between prefrontal, striatal, and hippocampal regions involved in salience processing and attention.
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.
In 121 paranoia-prone individuals, intravenous THC increased paranoid thoughts through heightened negative emotions and anomalous experiences, not through cognitive impairment.
Systematic review and meta-analysis found cannabis use associated with ~3x increased risk of new manic symptoms and worsened mania in existing bipolar disorder.
CBD reversed social withdrawal, cognitive deficits, and brain inflammation (astrocyte and microglial activation) in a schizophrenia mouse model, matching clozapine's effectiveness.
Among 96 bipolar manic patients, the dysphoric-psychotic subtype had higher rates of combined alcohol-cannabis use disorders and more suicide attempts than the pure elevated mania subtype.
In a 4-way crossover study of 48 cannabis users, CBD improved and THC impaired emotional face recognition, with their combination preventing impairment.
Review of schizophrenia etiology identified cannabis use as one of the two most important environmental risk factors, interacting with genetic vulnerability through epigenetic mechanisms.
Study of 205 psychosis patients found those who previously used prescription stimulants developed psychosis four years earlier on average, independent of cannabis use or family history.
56% of South African teens with first-episode psychosis reported cannabis use (96% male), with an average 7-month delay before treatment began.
Qualitative study found young adults with psychosis who quit cannabis naturally relied on recognizing broad harms, social support, diverse coping strategies, and peer pressure resistance.
Study of 144 adolescent offenders in Spain found 78.5% used drugs, with psychotic teens preferring cannabis and ADHD teens gravitating toward cannabis plus cocaine.
Among homeless people in BC, cannabis users had 32% psychotic disorder rates linked to childhood neglect, while stimulant users were more likely female and poly-substance users.
Twin study of nearly 10,000 teens found the cannabis-psychotic experience association is driven by shared environmental factors (69-100%) rather than genetics, with cannabis explaining only 2-5% of psychotic experience variance.
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).
A clinical review documented the rise of synthetic cannabinoids and other designer drugs, noting unpredictable toxicity, psychosis risk, and evasion of standard drug tests.
Network analysis of environmental risk factors found that cannabis use had the most direct connections to psychosis symptoms, with pathways often running through other psychiatric symptoms like anxiety and hostility.
Among 247 first-episode psychosis patients, escalating marijuana use in the 5 years before onset was strongly linked to faster psychosis development, with daily use doubling the rate independent of other substance use.
Comprehensive review of the endocannabinoid system — the brain's built-in cannabinoid network that THC hijacks when you use cannabis.
Meta-analysis of 37 studies found one-third of first-episode psychosis patients use cannabis, with regular use typically starting 6.3 years before psychosis onset and declining by nearly half after treatment.
Chronic cannabis use reduced attention-related brainwave responses in healthy people but not in those with schizophrenia, suggesting pre-existing endocannabinoid differences in schizophrenia.
Critical review finds CBD demonstrated antipsychotic effects comparable to standard medication in a clinical trial, with a side effect profile similar to placebo, potentially working through endocannabinoid system modulation.
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.
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.
Comprehensive review finding a disconnect between cannabis's "soft drug" reputation and growing evidence of cognitive impairment, psychosis risk, and gateway effects, particularly in youth.
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 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.
Narrative review finding substantial evidence linking cannabis to psychosis and other drug use, mixed evidence for depression and anxiety, with adolescent onset carrying the greatest psychiatric risk.
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.
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.
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.
Study of 260 first-episode psychosis patients finding early cannabis use and BDNF met-allele independently predicted younger psychosis onset, with early cannabis use more common in males.
Twin study of 2,793 young adults finding the cannabis-psychosis link is explained by shared genetics (55% correlation) plus a direct effect from cannabis use disorder to psychotic experiences, not the reverse.
Case-control study found that adolescents with first-episode psychosis and a family history of psychosis actually had milder positive symptoms at onset, challenging assumptions about genetic risk.
Small prospective study found significant verbal memory improvement (d = 1.07) in schizophrenia patients who achieved 28 days of cannabis abstinence.
Study found cannabis had opposite effects on brain signal filtering in schizophrenia (improved) versus healthy people (impaired), suggesting fundamental endocannabinoid system differences.
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.
The biology linking the endocannabinoid system to PTSD was strong, but clinical evidence for cannabis as treatment was weak. Nabilone showed real promise for nightmares specifically.
Review finding cannabis showed benefits for MS, Parkinson's, ALS, and late-stage Alzheimer's, but increased positive symptoms in schizophrenia and worsened bipolar disorder.
16-year MTA study follow-up found ADHD did not increase psychosis risk (5% vs. 4%), but cannabis use was significantly associated with psychotic symptoms in both groups.
Review finding synthetic cannabinoids are more potent, more dangerous, and more psychiatrically harmful than natural cannabis, with rapid chemical evolution evading regulation.
Patients with psychosis who used cannabis heavily before illness had higher schizophrenia polygenic risk scores, with the largest effect in those who started before age 18.
Psychotic patients with adolescent cannabis use showed less gray matter loss than those without, suggesting cannabis-associated psychosis may be a distinct subtype with less underlying brain pathology.
Adolescent synthetic cannabinoid exposure triggered schizophrenia-like dopamine changes in genetically susceptible rats but not in non-susceptible rats, modeling the human gene-environment interaction.
Cannabis-using psychosis patients were initially diagnosed with severe mental illness at lower rates (20% vs 53%), but both groups reached 80% severe diagnoses by second hospitalization.
Umbrella review of 98 associations found only five truly robust risk factors for schizophrenia: childhood adversity, cannabis use, obstetric complications, adult stress, and low folate.
People who got psychotic symptoms from THC already had higher hippocampal brain activity during learning under placebo, suggesting a pre-existing neural marker of vulnerability.
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.
Both maternal (38% increase) and paternal (44% increase) cannabis use during pregnancy predicted offspring psychotic-like experiences at age 10, suggesting shared genetics rather than direct prenatal exposure.
Mice with a schizophrenia risk gene showed normal endocannabinoid system development across 8 time points, suggesting their heightened cannabis sensitivity operates through other mechanisms.
Review finds synthetic cannabinoids bind brain receptors with much higher potency than natural cannabis, causing psychosis, kidney failure, cardiac problems, and death.
Six-year follow-up of 161 early psychosis patients found cannabis use predicted more hospital readmissions and longer stays, especially in male and Black patients.
THC challenge study found never-users experienced more psychotic symptoms and brain disruption than modest prior users, suggesting even limited cannabis exposure creates tolerance-like neuroadaptation.
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.
Review of 13 studies found that COMT and other dopamine-related gene variants modulate how cannabis impairs working memory, attention, and other cognitive functions.
Translational review of CBD research identifies established anxiolytic, antipsychotic, and neuroprotective properties with emerging evidence across epilepsy, PTSD, depression, and other conditions.
Review links cannabinoid receptor activity in glial cells to schizophrenia pathology, suggesting these brain support cells could be a new therapeutic target via the endocannabinoid system.
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.
Review found synthetic cannabinoids trigger new-onset psychosis and relapses, with effects more complex and potentially more severe than natural cannabis due to full agonist pharmacology.
Crossover fMRI study found 600mg CBD enhanced fronto-striatal brain connectivity in 16 healthy males, offering a potential neural mechanism for its antipsychotic properties.
THC exposure dampened human neuron gene responses to stimulation, with changes in synaptic and glutamate pathways overlapping schizophrenia, autism, and intellectual disability gene patterns.
Review proposed CBD as treatment for cannabis users with early psychosis, based on evidence of antipsychotic properties and ability to counteract THC's psychotogenic, anxiogenic, and cognitive effects.
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.
Longitudinal study found higher schizophrenia genetic risk predicted stronger cannabis use increases during ages 16-20, with no relationship to alcohol or tobacco, supporting shared genetics between schizophrenia and cannabis use.
Systematic review found synthetic cannabinoids in 10-13% of acute psychiatric patients, associated with higher psychotic symptoms than natural cannabis, and capable of triggering new-onset psychosis.
Mouse study found chronic THC rewired serotonin receptors toward a pro-psychotic signaling pattern via the Akt/mTOR pathway. Rapamycin blocked the effect.
Randomized study found clozapine reduced cannabis craving and amygdala cue reactivity significantly more than risperidone in schizophrenia patients with cannabis use disorder.
Critical review found CBD shows distinct promise for psychosis, anxiety, and withdrawal symptoms, each through different pharmacological mechanisms, but needs larger controlled trials.
Human Connectome Project analysis found cannabis-dependent individuals had hyperconnectivity in dopamine-related brain regions (striatum, midbrain), most pronounced in those who started youngest and reported high negative emotionality.
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.
Study of 265 early psychosis patients found CUD was a significant violence risk factor, with two high-risk profiles: CUD + impulsivity, or CUD + lack of insight + non-adherence. Good insight and adherence moderated the risk.
Review of 66 studies concluded cannabis doubles psychosis risk in vulnerable individuals, with dose-response and age-of-first-use effects, and gene-environment interactions modulating individual susceptibility.
Largest cannabis GWAS (184,765 people) found 8 significant variants, CADM2 as the top gene, 11% heritability, and Mendelian randomization evidence that schizophrenia risk causally increases cannabis use.
Study of 247 first-episode psychosis patients found cigarette smoking age, poor childhood academics/sociability, and trauma all predicted heavier premorbid marijuana use before psychosis onset.
Brain imaging found that schizophrenia-related gray matter reductions were the same whether patients had a history of cannabis/alcohol use or not.
Using incentive-based monitoring, 42% of cannabis-dependent schizophrenia patients achieved 28 days of verified abstinence - statistically similar to the 55% rate in non-psychiatric controls.
Among 829 hospitalized psychosis patients, those with both cannabis and tobacco use disorders had the highest rates of additional substance use problems, highlighting the need for comprehensive screening.
Review of preclinical evidence explains how adolescent THC exposure may disrupt the brain's inhibitory GABA system in the prefrontal cortex, potentially triggering schizophrenia-like dopamine dysregulation.
Systematic review of 70 studies (3,000+ patients) found evidence that cannabis-using psychosis patients may have distinct neurobiological profiles from non-using patients, supporting the need for tailored treatments.
First-episode schizophrenia patients who used cannabis gained significantly less weight during 12 months of antipsychotic treatment, with less metabolic deterioration than non-users.
Case series found that substituting street cannabis with a low-THC medicinal cannabis variant was not effective for treating cannabis use disorder in seven psychosis inpatients.
The reasons teens gave for starting cannabis - seeking sedation, stimulation, social acceptance, or recreation - predicted their schizophrenia risk and symptom severity.
Review argues that cannabinoid and glutamate systems converge on disrupted GABA interneuron function, unifying two major models of schizophrenia through their shared effects on theta and gamma brain oscillations.
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.
Cochrane review of 8 trials found no clear differences between antipsychotics for dual diagnosis patients, though one small study suggested clozapine may reduce cannabis craving more than risperidone.
Pilot study found schizophrenia patients accepted low-THC cannabis variants but preferred their usual high-potency product, supporting the feasibility but highlighting challenges of cannabis substitution.
Among 1,790 psychosis patients, daily cannabis use was linked to suicide attempts only until depression, loneliness, and homelessness were accounted for, suggesting these factors drive the apparent association.
Pilot fMRI found schizophrenia patients had abnormal brain network connectivity that actually normalized after cannabinoid administration, correlating with improved working memory performance.
A review of synthetic cannabinoid toxicities documented severe effects across multiple organ systems including cardiac arrest, psychosis, seizures, and kidney failure, plus deaths from contaminated products.
Adolescents in the ED after synthetic cannabinoid use had 3.4x higher odds of coma and 3.9x higher odds of seizures than those using traditional cannabis, showing a distinct and more dangerous toxicity profile.
Among 230 schizophrenia patients in Pakistan, ongoing cannabis use was linked to treatment resistance even after excluding non-adherent patients, with over 60% of the cohort being treatment-resistant.
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.
A systematic review found CBD improved schizophrenia symptoms (especially early-stage) and reduced cannabis withdrawal when combined with THC, with blood anandamide levels as a potential biomarker.
Cannabis users with two copies of a specific FAAH gene variant had 10x higher odds of a first psychotic episode, identifying a gene-environment interaction that could explain selective psychosis risk.
A Lancet meta-analysis of 83 studies found scarce evidence that cannabinoids help depression, anxiety, PTSD, or other mental disorders, with THC products doubling adverse event rates versus placebo.
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.
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.
A systematic review of 1,301 papers found only 27 qualifying studies of CBD for psychiatric disorders, with limited but promising signals for substance use, psychosis, and anxiety.
A review found CBD shows therapeutic potential across autism, anxiety, psychosis, pain, epilepsy, and neurodegenerative diseases, with mainly diarrhea and somnolence as side effects.
Cannabis-related pediatric ER visits are rising, ranging from accidental ingestion (hyperkinesis, coma in young children) to chronic hyperemesis and psychosis in adolescents.
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.
A review found cannabinoid receptors modulate dopamine, serotonin, noradrenaline, GABA, glutamate, and opioid systems, explaining the broad spectrum of cannabis effects on mental health.
A controlled study found a single low IV dose of THC caused symptoms in 94% of healthy volunteers, with women experiencing significantly more negative effects and all physical reactions.
Antipsychotic-naive psychosis patients with recent cannabis use showed more excitement symptoms initially but responded better to treatment at 10 weeks, suggesting a potentially more treatable psychosis subtype.
Review of evidence suggesting CBD has antipsychotic properties through a unique non-dopamine mechanism, potentially offering a new treatment class for psychotic disorders with fewer side effects.
Retrospective study of 1,661 psychiatric inpatients found synthetic cannabinoid users didn't have longer stays or need higher antipsychotic doses than cannabis users, while both groups had shorter stays than non-drug users.
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.
Comprehensive review finding CBD has established efficacy for epilepsy, early clinical signals for anxiety and psychosis, and preclinical-only evidence for depression and Alzheimer's.
Analysis of the landmark ABCD study found prenatal cannabis exposure associated with increased psychosis proneness in children, especially when mothers continued use after knowing they were pregnant.
Clinical review for psychiatrists finds synthetic cannabinoids cause faster dependence, worse psychiatric symptoms, more dangerous withdrawal, and physical effects including seizures and death compared to natural cannabis.
Review finds the cannabis-schizophrenia causal hypothesis remains unproven after decades of research, with three competing explanations and significant gaps in social, cultural, and non-Western evidence.
Systematic review of 14 RCTs (1,629 participants) finds cannabis-based medicines improved symptoms across multiple mental disorders as adjuncts but achieved no remissions, with larger trials needed.
Rat study identifies ERK1-2 phosphorylation in the hippocampus as the molecular mechanism by which THC causes psychosis-like dopamine dysregulation and CBD reverses it.
First systematic review of cannabis effects on the endocannabinoid system finds chronic use downregulates CB1 receptors in a pattern that may overlap with changes observed in psychosis.
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.
Systematic review of CBD in psychiatry finds limited evidence for cannabis withdrawal, addiction, psychosis, and social anxiety, with few side effects.
Review of multiple evidence types consistently links cannabinoid exposure to persistent cognitive deficits and psychosis risk, with adolescence as a critical vulnerability window.
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.
Adolescent THC unexpectedly attenuated dopamine dysfunction caused by prenatal immune activation in rats, challenging the simple two-hit model of schizophrenia.
Review finds limited support for cannabis benefits in mental illness, growing evidence of harm in psychosis and mood disorders, and proposes a framework for understanding addiction vulnerability.
Cannabis-related psychiatric disorders tied with schizophrenia (31.6% each) as the leading reason for psychiatric hospitalization at a South African mental health unit.
Adolescent THC caused premature dendritic pruning and altered gene networks in rat PFC neurons, with dysregulated networks overlapping schizophrenia-associated pathways.
JAMA Psychiatry meta-analysis of 18 studies finds elevated anandamide in CSF and blood of schizophrenia patients, highest early in illness and inversely related to symptom severity.
Colorado study found edible cannabis accounted for 0.32% of THC sales but 10.7% of cannabis ER visits, with higher rates of psychiatric, intoxication, and cardiovascular events.
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.
In 404 first-episode psychosis patients, tobacco, alcohol, and cannabis use each predicted worse treatment outcomes over two years, with tobacco linked to the most negative effects.
CBD reversed memory and social deficits in female rats from a schizophrenia model, but reduced social behavior in healthy rats.
In a large Asian multi-country study, schizophrenia patients with lifetime cannabis use had higher rates of aggressive behavior and were more likely to receive long-acting injectable antipsychotics.
A review maps cannabis-related psychosis through DSM-5 categories, showing a continuum from intoxication to cannabis-induced psychotic disorder to schizophrenia.
Overexpressing a cannabinoid receptor regulatory protein (CNRIP1) in rat brains produced schizophrenia-like behavioral and dopamine system changes.
A Danish study of over 3 million people found that schizophrenia significantly increases the risk of subsequently developing substance abuse, with cannabis showing the highest risk.
Colorado EDs have seen rising cannabis-related presentations including psychosis, CHS, cardiac events, and pediatric exposures since legalization.
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.
Cannabis use in psychosis patients was associated with antipsychotic treatment failure, including more medication switches and higher clozapine use.
Since legalization, Colorado has seen increases in psychosis, suicide, substance abuse, motor vehicle fatalities, pediatric exposures, and other harms.
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 auditory processing (MMN) than non-using patients, possibly reflecting a less impaired subgroup.
Cannabis-using psychosis patients were more dissatisfied with medication and rehospitalized more, but long-acting injectable antipsychotics reduced this risk.
At 10-year follow-up, first-episode psychosis patients who quit cannabis had outcomes matching never-users, while persistent users fared significantly worse.
PET brain imaging found altered CB1 receptor binding across cannabis use disorder, alcohol use disorder, schizophrenia, PTSD, and eating disorders.
Cannabis use history predicted longer delays before treatment in first-episode psychosis patients, alongside age and negative symptoms.
CBD given during adolescence prevented schizophrenia-like symptoms and normalized cannabinoid receptor changes in a rat model, while haloperidol did not.
Study of 83 first-episode psychosis patients found Moroccan immigrants had lower functioning and education but less cannabis use than Spanish-born patients.
10-year follow-up found women had higher early psychosis recovery rates (50% vs 31%) during specialized care, but the gap narrowed after discharge to community services.
A genome-wide study found a P2RX7 gene variant associated with psychotic experiences in cannabis users, replicated in a second cohort. THC and CBD affected the P2X7 receptor differently depending on genotype.
In a large NAPLS study of 543 individuals at clinical high risk for psychosis, slower startle responses predicted psychotic conversion (especially in females), and cannabis use showed opposite effects on sensory gating compared to healthy controls.
A study of 128 participants found chronic synthetic cannabinoid users had higher neuroticism, lower agreeableness, and greater schizotypal traits than natural cannabis users or non-users, suggesting SC users may be more psychiatrically vulnerable.
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.
A review found clear evidence that cannabis affects hippocampal function but weaker evidence for increased striatal dopamine, suggesting the cannabis-psychosis pathway may be more about hippocampal dysfunction than direct dopamine effects.
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.
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.
A review of animal models found adolescent cannabis exposure interacted synergistically with early-life maternal deprivation and immune activation to produce schizophrenia-like outcomes, with important sex differences.
Prospective study of 214 first-episode psychosis patients found continued cannabis use was associated with increased depression in those with high insight and medication adherence after one year.
Prospective study found 21% of first-episode schizophrenia patients had breakthrough psychosis despite long-acting antipsychotic injections, with cannabis use as an independent predictor.
Small retrospective study found 47% of first-episode mania patients who were screened tested positive for cannabis, higher than general population rates.
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.
Mega-analysis of 400 IV THC infusions found psychosis-like symptoms in 45% of healthy volunteers, with effects increasing with dose and decreasing with regular cannabis use history.
Systematic review of 8 studies with 210 participants found limited evidence for CBD as an antipsychotic but noted its favorable side effect profile compared to standard medications.
Study of 119 acutely psychotic patients found cannabinoid users showed an unusual inverse relationship between IL-6 inflammation and psychosis severity, with synthetic cannabinoid users more likely to need emergency sedation.
Portuguese hospital data showed cannabis-related psychosis hospitalizations increased 29-fold from 2000 to 2015, rising from under 1% to over 10% of all psychosis admissions.
Study of 165 schizophrenia patients found substance use disorder quadrupled self-harm risk, with cannabis and synthetic cannabinoids most commonly abused among those who self-injured.
Umbrella review of 26 meta-analyses confirms cannabis use is linked to increased psychosis risk, dose-dependent onset, earlier presentation, and higher relapse rates in psychotic patients.
Meta-analysis of 15 controlled studies confirms THC induces psychotic, negative, and general psychiatric symptoms with large effect sizes in healthy people, while CBD shows no consistent protective effect.
Longitudinal study of 437 homeless adults in Vancouver found that co-occurring substance use and psychotic disorders were associated with the highest mortality risk over 10 years.
Meta-analysis of two nationwide studies found daily cannabis use associated with 60% higher odds of violence in people with psychotic disorders, though stimulant and depressant use carried higher risks.
Systematic review of 25 CBD studies (927 patients) found the best evidence for anxiety and psychosis, with wide dosing variation and generally mild side effects.
Study of 106 psychiatric inpatients found 25.5% used cannabis the week before admission, but psychotic diagnosis, not cannabis dose, was the main predictor of symptom severity.
Among 938 young adults with first-episode psychosis, one-third had persistent cannabis use at 1 year with worse symptoms, while those who reduced use showed significant improvement.
Combining a serotonin 5-HT2A blocker with CB1 blocker improved prepulse inhibition in a schizophrenia mouse model, while neither cannabinoid drug worked alone.
Prospective study of 265 early psychosis patients found starting cannabis before age 15 was associated with 4.5 times higher odds of violent behavior.
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.
Study of 910 students found cannabis use predicted psychosis-like traits, with aberrant salience (abnormal importance assignment) mediating the relationship.
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.
Study of 1M+ schizophrenia inpatients found cannabis use disorders independently associated with 38% higher medication non-compliance after adjustments.
Systematic review found 10 of 12 studies support a cannabis-psychosis link, with THC identified as the primary risk and CBD as potentially therapeutic.
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.
Case of a long-time marijuana user who developed paranoid psychosis within one month of switching to "dabs" with up to 80% THC.
First clinically-focused systematic review found CBD tentatively supported for social anxiety and adjunctive schizophrenia, with high-THC showing no depression benefit.
Study of 71 schizophrenia patients found lifetime cannabis users had greater deficits in emotional expression, anticipatory pleasure, and social functioning.
Review of recent trials found CBD reduces positive psychotic symptoms but not negative symptoms, with inconsistent cognitive effects and generally good tolerability.
In a rat schizophrenia model, only the lowest THC dose (0.1 mg/kg) reversed social withdrawal, while higher doses worsened symptoms in healthy rats.
Cannabis use elevated the anti-inflammatory marker sgp130 in 401 schizophrenia patients but not 242 bipolar patients, suggesting diagnosis-specific immune modulation.
Postmortem brain study found CB1 receptor expression is highest fetally, drops after birth, is decreased in schizophrenia, and follows a COMT-genotype-dependent trajectory.
A South African study found 55.6% of patients with psychotic disorders had co-occurring substance use disorders, with cannabis use disorder being the most common at 34.3%.
Heavy cannabis use was linked to lower BDNF levels in first-episode psychosis patients who had never taken antipsychotics, but not in healthy volunteers, suggesting vulnerability-specific effects.
Cannabis use and subclinical psychosis traits showed consistent positive correlations in the general population, with one significant genetic link: social anhedonia was inversely correlated with cannabis use frequency.
The first PET study of brain FAAH in psychosis found lower enzyme levels predicted more severe positive psychotic symptoms (large effect size), suggesting FAAH as a potential biomarker and treatment target.
A longitudinal brain imaging study of 706 teens found that cannabis-related psychotic-like experiences were partially mediated by reduced growth of the uncus in the parahippocampal gyrus between ages 14 and 19.
A systematic review of 11 controlled trials found insufficient evidence for THC or CBD in schizophrenia treatment, with THC potentially worsening psychosis and CBD showing inconsistent benefits.
A review of 10 clinical studies found CBD may reduce psychotic symptoms caused by THC and positive symptoms of schizophrenia, though results for treating cannabis use disorder were mixed.
In a controlled THC study of 36 men, both a genetic variant (AKT1 rs1130233) and DNA methylation independently influenced how THC affected fear-related brain activity, with the epigenetic state partially mediating the genetic effect.
In a study of nearly 3,000 people with psychotic disorders, cannabis users had lower quality of life and worse functioning. Neither starting nor stopping cannabis changed outcomes within one year, suggesting accumulated effects from years of use.
In 124 patients with schizophrenia in a high-security hospital, cannabis use disorder was not linked to violence or impulsivity. Alcohol use disorder was nearly four times more likely to be associated with violent behavior.
Cannabis only increased psychosis risk in people with pre-existing elevated inflammation, providing the first human evidence for a two-hit hypothesis. Cannabis did not cause the inflammation itself.
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.
THC caused dose-dependent repetitive behavior in zebrafish that was reduced by an antipsychotic and a CB2 receptor blocker but not a CB1 blocker, offering a new model for studying cannabis-psychosis links.
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.
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.
Rats exposed to THC around birth showed lasting epigenetic changes in dopamine receptor genes and schizophrenia-like behaviors, but adolescent CBD treatment reversed the damage. Similar epigenetic changes were found in human schizophrenia patients.
Study of 437 homeless adults found cannabis use before age 15 was linked to substance-induced psychosis while use after 15 was linked to schizophrenia, with corresponding brain differences.
Study of 284 first-episode psychosis patients found tobacco-only users had a distinct clinical profile, while adding cannabis was linked to 2.5 years earlier onset and more hallucinations and disorganized thinking.
Systematic review found THC and CBD have opposite brain effects, with THC increasing and CBD decreasing activation, particularly in regions linked to psychosis.
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.
Danish national registry data showed cannabis-induced psychosis incidence more than doubled from 2006-2016, while alcohol-induced psychosis declined and other substance-induced psychoses remained stable.
Study of 88,637 individuals found genetic risk for schizophrenia did not predict cannabis use disorder, while genetic risk for ADHD did, challenging the shared-genetics hypothesis for the cannabis-schizophrenia link.
Mice with reduced Reelin protein showed worse social, behavioral, and stress outcomes after adolescent THC exposure than normal mice, suggesting genetic factors influence cannabis vulnerability.
Study of 50 treatment-resistant schizophrenia patients found THC consumers had nearly double the DNA methylation in the NRXN1 gene promoter compared to non-consumers, suggesting epigenetic links between cannabis and psychosis.
Large genetic study found cannabis use disorder (but not simply trying cannabis) was robustly associated with schizophrenia risk after controlling for tobacco, with mixed evidence on whether the relationship is causal.
Case report of a 52-year-old man with no psychiatric history who developed first-episode mania after self-medicating COVID-19 with cannabis-containing home remedies.
Community study of 2,142 people found heavy drinking, cannabis use, and stressful events each independently predicted psychosis, with two co-occurring risk factors raising incidence from 1.6% to 17.7%.
Small pilot trial of smoked CBD cigarettes for acute psychosis found no significant symptom differences, but the placebo group needed more antipsychotic medication while the CBD group did not.
Study of 247 first-episode psychosis patients found childhood violence and environmental adversity was the strongest predictor of premorbid substance use, more than interpersonal abuse or neglect.
Two experiments with 1,601 young adults found that learning about genetic predisposition for cannabis-related psychosis risk increased intentions to avoid marijuana, especially among prior users.
Two patients with untreated schizophrenia caused severe eye injuries to themselves while intoxicated on synthetic cannabinoid K2, both hallucinating a bug behind their eye.
A CB1 receptor positive allosteric modulator called GAT211 showed antipsychotic-like effects in rats by reducing dopamine-related hyperactivity, unlike THC which did not block the same signaling pathway.
Cannabis use before first psychiatric hospitalization in Ontario rose from 17% to 26% over a decade, with nearly half of young adults (18-24) using cannabis before admission by 2017.
A schizophrenia patient hospitalized 30 times in 8 years reported significantly less need for illegal cannabis and no further hospitalizations after switching to low-THC CBD cigarettes.
Two controlled studies found cannabis reliably increased psychotic-like symptoms, but CBD in the cannabis did not reduce these effects. Adolescents were actually less vulnerable to acute psychotic effects than adults.
A study of 605 young adolescents (mean age 13) found cannabis users scored much higher on hopelessness, depression, and anomalous reality perception, with hopelessness being the strongest unique predictor of use.
A study of 40 cannabis-dependent patients found significant psychiatric symptoms but no changes in thyroid hormones or cardiovascular measures compared to controls, suggesting tolerance to some but not all effects.
In a Danish cohort of 1,632 children, early cannabis use by age 15 was the strongest independent predictor of subclinical hypomania at age 16, with a 3-fold increased risk.
Small crossover trial finds CBD increases hippocampal glutamate in psychosis patients, correlating with reduced symptom severity.
fMRI study finds single CBD dose partially normalizes altered brain activation in psychosis patients toward patterns seen in healthy controls.
Comparative study finds cannabis-induced psychosis and schizophrenia have distinct symptom profiles, with different patterns of speech and thought disorder.
Study finds cannabis users show elevated neurological soft signs regardless of psychosis status, suggesting cannabinoids affect brain circuits involved in motor and sensory processing.
Mouse study finds CBD prevents psychosis-like behavior with effects lasting 24 hours, involving DNA methylation changes in brain regions implicated in schizophrenia.
Study of 102 psychosis patients finds earlier cannabis use linked to altered cerebellar brain network structure previously implicated in schizophrenia.
Study of 247 first-episode psychosis patients finds cannabis users had less social withdrawal but more severe delusions, with no cognitive differences.
Large EU-GEI study finds genetic schizophrenia risk and daily cannabis use independently contribute to positive psychotic symptoms in both patients and healthy controls.
Large EU-GEI study finds daily high-potency cannabis use associated with the most severe positive psychotic symptoms in a dose-response pattern, while cannabis use was linked to fewer negative symptoms.
Study of 307 inpatients finds cannabis-induced psychosis differs from schizophrenia with fewer negative symptoms and more mania, with cannabis use linked to nearly a decade earlier first hospitalization.
Prospective study finds cannabis-using psychosis patients have higher dissociation and worsening functioning over 8 months, while non-users improve.
Study of 62 FEP patients finds cannabis use and treatment delay independently contribute to dissociative symptoms, though cannabis does not extend the untreated period itself.
Rat study finds prenatal THC creates a latent dopamine dysfunction in offspring that emerges as psychotic-like behavior only when triggered by stress or drug challenge.
Double-blind crossover study in 18 cannabis users finds CBD significantly reduces THC's psychotic-like effects when co-administered as a full-spectrum extract.
Multi-national study found first-episode psychosis patients reported more psychotic-like experiences during cannabis intoxication than controls, with sensitivity increasing at higher use levels, while euphoric experiences did not differ.
Study of 91 participants found that psychosis patients without cannabis history had worse smooth pursuit eye movements than those with cannabis history, suggesting less severe neurobiological impairment in cannabis-associated psychosis.
Study of 1,544 twins found that while cannabis use was associated with higher psychoticism scores, within-twin-pair comparisons showed no causal effect, suggesting shared genetics explain the link.
Study of 98 first-episode schizophrenia patients found cannabis users responded similarly to antipsychotic treatment over 24 months, but more frequent use predicted higher relapse risk.
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.
Study of 370 involuntary psychiatric patients found THC-positive patients were 2.29 times more likely to be readmitted within a year and more likely to be prescribed benzodiazepines at discharge.
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.
Study of 404 first-episode psychosis patients found cannabis users were less likely to develop metabolic syndrome, with lower triglycerides and higher HDL cholesterol.
Within-person analysis of nearly 8,000 people over 10 years found cannabis use predicted a sevenfold increase in psychotic experiences, but psychotic experiences did not predict cannabis use, supporting a causal direction.
Among 109,308 UK Biobank participants, cannabis use was strongly linked to psychotic experiences, with people in the top fifth of schizophrenia genetic risk showing nearly 10 times the effect size compared to those in the bottom fifth.
Study of 517 hospitalized patients with schizophrenia found cannabis use was not independently associated with longer hospital stays or more frequent admissions after adjusting for covariates.
Survey of 1,034 college students found higher cannabis use was associated with more hallucinations (independent of depression) and delusional ideation that was more distressing and held with greater conviction.
Three young men with autism developed mania or psychosis after using CBD/THC products, highlighting potential psychiatric risks of cannabis use in the ASD population.
Study of 167 clozapine-treated schizophrenia patients found cannabis use and trauma were associated with psychotic symptoms but not primary negative symptoms, suggesting distinct pathways.
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.
Meta-analysis of 19 studies (5,191 participants) found cannabis users had significantly worse formal thought disorder whether healthy, in first-episode psychosis, or with schizophrenia.
GRADE-based clinical guidelines found no evidence to recommend any specific antipsychotic for schizophrenia patients with cannabis use disorder, highlighting a critical evidence gap.
A review of CBD science following Malawi's cannabis legalization highlights epilepsy treatment, neuroprotective potential, and a novel proposal for malaria-related brain injury.
Boosting anandamide in adolescent rats reversed schizophrenia-like cognitive and social deficits through distinct CB1 and CB2 receptor pathways.
In a 3-year follow-up of first-episode schizophrenia patients, 93.2% of those who relapsed used cannabis, compared to 56.7% of those who stayed in remission.
A review warns that cannabis exposure in autistic individuals may increase psychosis risk through epigenetic effects on shared genetic pathways, with potential intergenerational consequences.
Cannabis-induced psychosis ER visits doubled from 2015-2019 in Ontario and Alberta, but statistical analysis found no significant increase attributable to Canada's 2018 legalization.
A survey of 70 psychosis patients found 86% willing to try CBD treatment, with most expecting symptom improvement and fewer side effects than antipsychotics.
A review argues CBD's antipsychotic effects and low side effect profile make it potentially ideal for early-phase psychosis, where minimizing adverse experiences is crucial.
An international expert consensus concluded cannabis is a component cause of psychosis with dose-response and age-response relationships, but alone is neither necessary nor sufficient.
Cannabis users reported more schizotypy traits and subjective aberrant salience experiences, but showed normal salience processing on an objective lab task.
Narrative review found emerging evidence that CBD may address positive, negative, and cognitive symptoms of schizophrenia with fewer side effects than standard antipsychotics.
Large study of 6,229 people found lifetime cannabis use was linked to better facial emotion recognition across schizophrenia patients, siblings, and healthy controls.
German hospital data showed a 4.8-fold increase in cannabinoid-related psychiatric admissions from 2000-2018, while alcohol and schizophrenia admissions remained stable or declined.
Brain imaging showed schizophrenia patients with cannabis use had thinner cortex than cannabis-induced psychosis patients, supporting distinct pathophysiology.
Among 265 first-treatment psychosis patients, cannabis use was not linked to negative beliefs about antipsychotic medications despite predicting poor adherence.
Controlled trial showed THC and CBD each altered brain responses to unexpected sounds, with CBD modifying THC's effects differently in frequent vs less-frequent users.
THC modulates reward-related brain regions in ways that correlate with psychotic symptoms. CBD appears to act in the opposite direction on the same regions.
Schizophrenia patients with cannabis use disorder showed different blood biomarker patterns than those with schizophrenia alone, with elevated serotonin receptors and inflammation markers absent in dual-diagnosis patients.
In a schizophrenia rat model, THC-only cannabis vapor worsened brain oscillation deficits while balanced THC/CBD vapor preserved or enhanced brain activity.
In rats, CBD reduced risperidone-induced blood sugar elevation, movement abnormalities, and muscle stiffness without impairing cognition.
In Lebanon, cannabis use disorder nearly tripled the odds of needing intensive psychiatric outreach for psychosis, alongside other severity markers.
Only 16 controlled studies exist for CBD in psychiatric disorders. Most promising evidence for psychosis and anxiety, but not enough for clinical recommendations in any condition.
In 246 first-episode psychosis patients, 78% had used cannabis, with 94% starting use years before psychotic symptoms. Earlier exposure predicted worse outcomes.
Researchers proposed a "cannabinoid hypothesis" of schizophrenia describing multiple biological pathways through which THC may trigger psychosis, paralleling established dopamine and serotonin hypotheses.
Study of 667 schizophrenia patients found very high non-right-handedness (42.4%), which was associated with cannabis use disorder and learning disabilities, suggesting shared neurodevelopmental origins.
Review of 41 studies found cannabis was the most commonly abused substance in dual diagnosis patients with psychosis, and aripiprazole was the most studied second-generation antipsychotic treatment.
Review of 370 South African psychiatric inpatient records found nearly half (48.9%) used cannabis, with use strongly linked to male sex, alcohol co-use, and more frequent hospital readmissions.
National data found 129,070 psychosis-cannabis hospitalizations in 2017, with the Pacific division (mostly legal states) having 55% higher odds and a significant correlation between legality and hospitalization rates.
Review found cannabis is a risk factor for violence in early-phase psychosis, with impulsivity as a potential mediating mechanism linked to cannabis effects on frontal brain regions.
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.
Review explained how the developing endocannabinoid system makes adolescent brains uniquely sensitive to THC, particularly through disruption of still-maturing dopamine circuits linked to psychosis and addiction.
Focus groups with 16 young psychosis patients found they continued cannabis use not despite knowing risks but because they lacked alternative strategies for socializing, enjoyment, and mood management.
Nationwide Swiss data showed sharp increases in cannabis-related psychiatric hospitalizations from 1998-2020, concentrated in the 15-44 age range.
Review confirmed gender differences exist in cannabis-related psychosis, depression, and anxiety, but the direction varies. Women may be more vulnerable to mood effects; men may show stronger psychosis links.
Four patients with first cannabis-induced psychosis improved on lurasidone (74-128 mg/day) with symptom remission, functional recovery, and no significant side effects.
Systematic review of 6 studies found contingency management effectively reduced cannabis use and achieved abstinence periods in people with psychotic disorders or major depression.
Two-year study found methamphetamine, but not cannabis, predicted worse cognitive outcomes in first-episode schizophrenia patients.
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 study of 60 participants found cannabis-induced psychosis had fewer white matter abnormalities and more gray matter than schizophrenia with cannabis use.
Case report of a young adult with cannabis use, COVID history, and other complicating factors who developed severe psychosis but achieved complete recovery.
Study of 24 cannabis users found smoking high-THC cannabis changed DNA methylation enzyme levels in blood cells within hours, a potential link to psychosis risk.
Genome-wide study of 780,000+ people found shared genetic factor explaining 8.6% of schizophrenia risk, highlighting NCAM1 as a key gene linking smoking, cannabis, and psychosis.
Systematic review of 15 studies found cannabis use associated with aggression in PTSD and psychotic disorders, but causal conclusions cannot be drawn due to methodological limitations.
Controlled trial in 24 healthy people found a moderate dose of synthetic cannabinoid JWH-018 caused psychedelic effects, dissociation, amnesia, and confusion.
Study of 877 methadone patients found cannabis use shortened treatment retention by 3 years, but this effect was absent in patients with schizophrenia.
Colorado study found each increase in dispensary density was associated with 24% more psychosis ER visits after recreational legalization, while schizophrenia visits were unchanged.
Study of 1,099 people with psychotic disorders found those with atypical psychosis had early cannabis use rates (17.5%) closer to schizophrenia (11.5%) than psychotic bipolar disorder (5.3%).
London study of 2,130 catatonic episodes found 5.1% were substance-related, with cannabis the most frequently implicated substance. Cases increased between 2007 and 2016.
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.
Swedish conscript study found schizophrenia patients with adolescent cannabis history had earlier onset, more hospitalizations, and more hospital days than those without.
Study found clinical psychosis risk youth had elevated cannabis, alcohol, and tobacco use, while genetically at-risk youth (22qDel) had lower rates, with social and cognitive factors explaining the difference.
Meta-analysis of 3,053 schizophrenia patients found cannabis use associated with more positive symptoms and excitement but fewer negative symptoms, with no link to depression or disorganization.
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.
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.
Lancet Psychiatry study found significant genetic overlap between cannabis use and schizophrenia/bipolar disorder, with evidence of causal effects running in both directions.
Prospective study of 334 people at clinical high risk of psychosis found no association between baseline cannabis use and transition to psychosis over 2 years.
Multi-site study of 1,185 people found cannabis and childhood trauma interacted to predict earlier psychosis onset, with hippocampal volume as a biological mediator.
A study of nearly 10 million people found ER visits for substance-induced psychosis carried a 163-fold increased risk of later schizophrenia, with cannabis showing the highest transition risk of any substance.
Ontario data showed no increase in cannabis psychosis ER visits after initial legalization, but a 30% jump after retail and product expansion, driven by youth aged 19-24.
A review of purified CBD clinical trials found the strongest evidence for anxiety (17 RCTs), psychosis (8 RCTs), PTSD (4 RCTs), and substance abuse (3 RCTs), but not for pain or sleep.
Scoping review found no proven intervention for reducing cannabis use in young adults with psychosis, though MI, CBT, and family training show minimal evidence.
15-year Swedish study of 12,143 CUD patients found 23% readmission rate, with schizophrenia (54% higher), low education (40% higher), and ages 18-35 as top risk factors.
Mini-review of 12 studies found suggestive evidence that cannabis use increases suicide risk in schizophrenia, particularly among men and during first-episode psychosis.
Among 62 first-episode psychosis patients, synthetic cannabinoid users showed worse symptoms, slower recovery, and higher aberrant salience than THC users or non-users.
Among 61 first-episode psychosis patients followed for 9 months, synthetic cannabinoid users had worse symptoms, more suicidal ideation, and poorer recovery than THC users or non-users.
Registry data from all three Scandinavian countries showed cannabis-induced psychosis doubled while alcohol-induced psychosis declined from 2000 to 2016.
Among 441 cannabis users, paranoid and dysphoric intoxication experiences were the strongest predictors of motivation to quit, more than psychosis-like hallucinations.
In 249 first-episode psychosis patients, polygenic risk scores for cannabis use predicted symptom trajectories, suggesting partially independent genetic factors for initiation vs. disorder.
EU-GEI study of 1,125 people found those who first used cannabis to cope with negative emotions had higher psychosis risk than those who started for social reasons.
National survey of 68,000+ US teens found nondisordered cannabis use (10.2%) associated with doubled odds of depression, suicidal ideation, and academic problems vs. non-use.
Prospective study of 56 patients found cannabis-induced psychosis presents with positive symptoms and improves steadily over one month after cannabis cessation.
Chart review of 110 teens found aripiprazole associated with shorter hospital stays (5.8 vs. 9.7 days) than risperidone for cannabis-related psychosis.
EU-GEI study of 2,112 people found cannabis use partially mediates the relationship between childhood adversity and first-episode psychosis.
Rome police seizures show hashish THC nearly doubled from 13.7% to 27.1% in seven years, with some samples exceeding 40% — and young males are the primary users.
Review finds cannabis increases psychosis risk, worsens outcomes in vulnerable youth, and recommends integrated treatment approaches for co-occurring use and psychotic symptoms.
Review proposes neuropsychological testing to differentiate cannabis-induced psychosis from schizophrenia, conditions that often look identical clinically.
Longitudinal study found continued cannabis use predicted worse outcomes in first-episode psychosis, with early intervention services only partially offsetting the disadvantage.
Study found tobacco dependence worsened cannabis withdrawal symptoms in both people with and without schizophrenia-spectrum disorders.
ABCD Study data linked prenatal cannabis exposure to blunted brain reward responses and psychotic-like experiences in youth, suggesting dopamine-related circuitry disruption.
Two large studies found daily high-potency cannabis use carried 5x psychosis risk independently of genetic predisposition, and schizophrenia genetics did not predict heavy cannabis use.
Across 14 European sites, lower homeownership and higher daily cannabis use prevalence each independently predicted psychosis incidence, with daily cannabis use specifically linked to affective psychosis.
New theoretical framework explains how cannabis and other psychotomimetic drugs can both relieve psychiatric symptoms (compensation) and increase psychosis risk (sensitization) through the same neurotransmitter systems.
Review argues that standard cannabis use questionnaires are unreliable in psychosis patients due to symptoms, cognitive deficits, and concealment, recommending quantitative biological measures instead.
Retrospective study of 317 Thai patients with cannabis-induced psychosis found rapid symptom improvement with antipsychotics (primarily risperidone) over 28 days, but 7% were diagnosed with schizophrenia within 1.3 years.
Systematic review of 41 studies reveals the endocannabinoid and stress hormone (HPA) systems interact bidirectionally in psychosis: THC affects stress hormones while childhood trauma alters endocannabinoid signaling.
In a Brazilian community sample, cannabis use was linked to worse disorganization symptoms among people at risk for psychosis but did not predict transition to full psychiatric disorders over 2.5 years.
A Swedish study of 1,820 patients with first-episode psychosis and cannabis use disorder found clozapine and long-acting injectable antipsychotics were most effective at preventing relapse and rehospitalization.
Psychotic subjects showed elevated DNA methylation at cannabinoid and dopamine receptor genes compared to controls, but active THC use reversed these changes, complicating their potential as biomarkers.
Ontario study matching 54,006 medical cannabis patients to 161,265 controls found a 38% higher risk of psychosis-related ER visits, increasing to 63% for those with no prior psychosis history.
Study of 80 male subjects found serum BDNF levels were highest in those with both cannabis use disorder and schizophrenia compared to either condition alone or tobacco-only controls.
A Danish registry study of 35,714 schizophrenia patients found cannabis-related cases used less antipsychotic medication but had more hospitalizations, suggesting a potentially distinct clinical profile.
Among 143 first-episode psychosis patients, cannabis use at program exit was linked to fourfold higher relapse risk and one-third the odds of continuing psychiatric care.
A 10-year follow-up of 192 first-episode psychosis patients found four symptom trajectories, with frequent cannabis use delaying remission and stimulant use triggering relapse.
Norwegian registry data showed cannabis-induced psychosis declined during COVID while stimulant-induced episodes rose, with recurrent patients more likely to switch between triggering substances.
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.
A scoping review found that cannabis exposure alters DNA methylation at genes tied to dopamine signaling, neurodevelopment, and cell survival, with links to psychiatric symptoms.
A study of 11,363 Ontario youth found cannabis use was associated with 11-fold psychosis risk during adolescence but no significant risk during young adulthood.
Content analysis finds most US states with legal cannabis have weak warning labels averaging 57 words, with almost none requiring mental health or psychosis risk warnings.
In a rat schizophrenia vulnerability model, adolescent THC impaired social behavior but did not worsen or interact with prenatal immune activation-induced cognitive deficits.
A 23-year-old with substance use history developed recurrent catatonic episodes after cannabis use, requiring ongoing lorazepam to prevent relapse.
Study of 104 psychotic disorder patients in Greenland found 68% had harmful cannabis use and 80%+ smoked daily.
Cannabis use among 187 forensic psychiatric patients rose after Canadian legalization, with over half showing mental health decline after use, though violence rates did not increase.
Four patients developed psychotic symptoms after abruptly stopping chronic cannabis use, suggesting withdrawal itself may trigger psychosis in vulnerable individuals.
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.
EU-GEI study across five European countries found cannabis use explained very little of the elevated psychosis risk among ethnic minorities, except in two specific subgroups.
Canadian survey of 13,527 cannabis users found that after legalization, only people with schizophrenia showed significant increases in daily use (9-fold higher odds), while other psychiatric groups showed no change.
Review of the past decade of research explains how cannabis triggers psychosis by disrupting the endocannabinoid system during adolescent brain development, affecting synaptic pruning and neurotransmitter signaling.
JAMA Psychiatry neuroimaging study found cannabis use disorder linked to elevated dopamine function in the same midbrain region associated with psychosis.
Twin study of 232 adolescents found cannabis use linked to psychotic-like experiences, driven by environmental rather than genetic factors, with no mediation by brain connectivity.
Genetic analysis of 200,000+ individuals found cannabis use disorder and schizophrenia share genetic roots — polygenic liability for each independently predicted the other condition.
Genetic risk scores for cannabis use disorder predicted schizophrenia even in people without documented cannabis use, suggesting shared genetic pathways between the two conditions.
Application of Bradford Hill causation criteria to longitudinal studies found substantial evidence that adolescent cannabis use may precipitate bipolar disorder in vulnerable individuals.
Italian study found area-level teen cannabis use was associated with higher first-episode psychosis rates and 12.9 months longer delays before treatment.
Meta-analysis of 13 studies found converging experimental and observational evidence that cannabis use causes paranoid symptoms, with THC-dominant products producing the strongest effects.
Kynurenine, a metabolite elevated in schizophrenia, amplified THC-induced motor impairment and behavioral effects in mice, possibly by raising THC blood levels.
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.
Large European case-control study found cannabis-associated psychosis risk declined after quitting and returned to never-user levels after about 37 weeks, though heavy high-potency users may retain elevated risk longer.
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.
Large study across four African countries found cannabis and other substance use patterns among people with psychosis varied significantly by country and sex, differing from Western research findings.
Crossover RCT found CBD pre-treatment (1000mg) worsened cannabis-induced memory impairment and psychotic symptoms in 30 patients with schizophrenia, contradicting the protective hypothesis.
Among 182 first-episode psychosis patients in South Africa, cannabis use was linked to worse psychotic symptoms across multiple domains, with HIV-positive cannabis users showing additional burden.
Analysis of 21.9 million Arizona hospital visits found cannabis-related visits were ~7 times more likely to involve psychosis, a stable pattern from 2016 to 2022.
Pilot trial with 101 young adults with psychosis found a digital cannabis harm reduction app was feasible (82% retention) and showed early signals of benefit.
A systematic review of 49 controlled studies across 11 mental health diagnoses found CBD may offer short-term anxiety relief and CBD/THC combinations helped with cannabis withdrawal and sleep, but THC worsened psychosis and no long-lasting benefits were found for any product.
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.
Prenatal THC exposure reprogrammed dopamine receptor expression in the prefrontal cortex of adolescent rats through epigenetic changes, with male offspring showing the strongest effects on D2 receptors, neuron excitability, and neural guidance systems.
A review of international trends suggests Germany should expect more cannabis-related ER visits after legalization, with Canada seeing doubled hospital admissions and acute intoxication as the top reason.
A Swedish study of 7,320 people found cannabis-induced psychosis had the highest relapse rate (25.7%) among all substance-induced psychoses, with 2.42x higher risk than alcohol-induced cases.
CBD reversed elevated dopamine neuron activity in both male and female rats in a schizophrenia model and corrected memory deficits in males.
First-episode psychosis patients who showed cognitive deterioration had higher cannabis exposure and environmental risk scores than those who maintained cognitive function.
Parents of youth who used cannabis described it triggering or worsening severe mental health crises, while frequently encountering healthcare providers who minimized cannabis-related risks.
Youth in early psychosis programs described cannabis as creating family tension around psychosis risk while some family members' own use created contradictory messages and even bonding opportunities.
Cannabis involvement among mass shooters doubled after medical legalization began in 1996, while remaining stable among non-firearm mass murderers, though causation cannot be established.
Mice given THC during adolescence showed lasting social deficits, sensorimotor gating problems, and disrupted cortico-striatal brain connectivity with altered dopamine receptor balance persisting into adulthood.
Mendelian randomization study using genetic data found potential causal links between cannabis use and increased risk of Parkinson's disease and ADHD in women.
Study of 93 people found lifetime cannabis use lowered the endocannabinoid 2-AG in schizophrenia patients, while non-clozapine antipsychotics altered CB2 receptors.
Analysis of 4+ million VHA patients over 18 years found cannabis legalization drove greater CUD increases among veterans with psychiatric disorders than those without.
Teen cannabis use has held steady despite legalization, but ER visits, child ingestions, and product potency have all increased—changing the risk landscape.
Longitudinal study using both self-report and hair THC analysis found cannabis use at 20 predicted increased psychotic-like experiences, worse mental health, and poorer functioning at 24.
In 62,000 Americans, the link between cannabis and psychotic-like experiences disappeared after accounting for methamphetamine, cigarette, and opioid use.
Denver Health data showed youth psychosis hospitalizations rose significantly after cannabis legalization, with CUD-involved cases quadrupling from 2.0 to 8.5 per 100,000 monthly.
An analysis of 121,061 Ontario schizophrenia patients found cannabis legalization was associated with a 26% decrease in cannabis-related ER visits for men and an 18.5% decrease in mental health ER visits for women.
A 10-year study of 320 first-episode psychosis patients found that most immune markers only predicted outcomes in cannabis users, suggesting inflammation and cannabis interact in shaping psychosis trajectories.
A meta-analysis of 47 longitudinal studies identified cannabis use as a novel risk factor for violence in psychosis (OR=3.34), comparable to criminal history (OR=3.50).
A massive meta-analysis of 359 animal experiments confirmed that adolescent cannabinoid exposure consistently produces schizophrenia-like behavioral changes including memory impairment, social deficits, and disrupted sensory gating.
A 13-year analysis of Canadian hospital data found cannabis-related hospitalizations rose 120% and ER visits rose 113%, driven largely by psychosis cases and youth intoxications.
A 16-year study of 52,000+ psychiatric admissions found cannabis users were more likely to need intensive care during the 3-5 day cannabis withdrawal window, especially women and older adults.
German national data shows cannabis-related medical diagnoses tripled between 2009 and 2021, rising faster than use prevalence, with the biggest increases in middle-aged adults.
Australian early psychosis service found medicinal cannabis THC concentrations nearly doubled in prescriptions written after psychosis onset, with 60% of patients experiencing attributed deterioration.
Interviews with 20 young adults at psychosis risk reveal coping motives and social pressure as top barriers to cutting back on cannabis, informing mobile intervention design.
A review of 55 studies found drug legalization and decriminalization had mostly neutral effects on population-level mental health outcomes including depression, anxiety, and 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.
Over a third of Irish drug users tried HHC before its 2025 ban, with 90% reporting negative effects—a cautionary tale about legal synthetic cannabinoid alternatives.
Two-hit rat study finds prenatal immune activation plus adolescent THC causes hidden brain changes visible on imaging and gene expression, even before behavioral symptoms appear.
Meta-analysis of 29 studies finds cannabis use in schizophrenia linked to 40% higher suicide attempt odds and 21% higher suicide death risk.
A review warns that 30 years of rising methamphetamine and high-potency cannabis use have fueled a growing wave of drug-induced psychosis, with up to half of cases progressing to schizophrenia.
An Ontario study of 13.6 million people found the share of schizophrenia cases linked to cannabis use disorder nearly tripled from 3.7% to 10.3% during a period of cannabis policy liberalization, reaching 18.9% among young men.
A PET imaging study found cannabis use was linked to significantly lower brain MAO-B (an astrocyte marker) in early psychosis and high-risk individuals, particularly in striatal regions associated with dopamine.
A review proposes that cannabis may trigger psychosis in genetically vulnerable individuals by disrupting glutamate signaling in the brain's default mode network, and outlines how to test this hypothesis.
A 3-year study of 279 bipolar patients found cannabis linked to earlier onset and more psychotic symptoms but not more hospital readmissions, while tobacco predicted higher relapse rates.
An ABCD Study analysis of 11,858 adolescents found psychosis symptoms were already rising before cannabis initiation, supporting self-medication and shared vulnerability models alongside any direct contributing risk.
British Journal of Psychiatry editorial argues cannabis policy should reduce psychosis harm while improving access to regulated medicinal products.
Systematic review applying Hill causality criteria found cannabis likely contributes to schizophrenia development (OR 2.88), with adolescent use carrying roughly double the risk.
Combined CBD and sodium nitroprusside during early brain development prevented schizophrenia-like symptoms in rats, with stronger effects in females than males.
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.
Systematic review of case reports found delta-8-THC is associated with psychosis and mood symptoms in young adults despite being marketed as a milder, legal alternative to regular cannabis.
Preprint companion to RTHC-00197 with additional detail: sex-balanced cohorts and extended testing confirm lasting hippocampal theta disruptions from adolescent cannabinoid exposure.
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).
Review of 22 studies found daily high-potency cannabis tripled dissociation risk in first-episode psychosis, with worse functional outcomes, though 75% improved after stopping cannabis.
Review of 62 studies found childhood trauma plus cannabis use amplified psychosis risk up to 31-fold, with earlier onset and worse outcomes than either factor alone.
Review of 50 studies found cannabis nearly tripled suicide risk in first-episode psychosis patients, with dose-dependent effects and identified high-risk intervention windows.
Systematic review of 85 studies found synthetic cannabinoids carry 4-5x higher psychosis risk than cannabis, with a distinct clinical syndrome termed "spiceophrenia."
Patients who continued cannabis after first psychotic episode had dramatically worse depression, 3x higher relapse rates, persistent suicidality, and no functional improvement over 9 months.
Systematic review of 38 studies finds high-potency cannabis, genetic predisposition, and environmental stressors interact to drive psychotic-like experiences in otherwise healthy people, with evidence of a bidirectional relationship.
Annals of Internal Medicine review of 99 studies (221K participants) finds high-THC cannabis consistently associated with psychosis and addiction, with mixed results for anxiety and depression depending on therapeutic context.
CBD reversed memory deficits, restored protective brain cells, and reduced neuroinflammation in a mouse model of schizophrenia, working through serotonin and cannabinoid receptor pathways.
Study of 573 psychosis cases found genetic and environmental risks (including cannabis) act independently, with schizophrenia-spectrum disorders driven more by genetics and affective psychosis by environment.
Review explains why cannabis-mental health findings seem contradictory: it depends on THC vs CBD content, use frequency, age, genetics, and other often-overlooked factors.
A genetic variant in the cannabinoid receptor 1 gene (rs1049353) differed in frequency between cannabis users who developed psychosis and those who didn't.
A 21-year-old with prior cannabis psychosis developed catatonia after resuming use, triggering rhabdomyolysis, kidney injury, and autonomic instability.
Study of 108 Dutch people with psychotic disorders found pain did not predict cannabis use, but those on less-sedating antipsychotics used more cannabis, suggesting different motivations than pain relief.
3-year study of 467 first-episode psychosis patients found distinct alcohol and cannabis trajectories: alcohol users maintained use while some cannabis users reduced it, though cannabis reducers still had higher hospitalization rates than abstainers.
A study of 412 young adults found cannabis use was associated with paranoid thinking only in those with a history of childhood trauma, not in those without.
A preclinical review suggests partial dopamine agonists like cariprazine could treat both schizophrenia and cannabis addiction by stabilizing dopamine signaling.
A nonjudgmental two-session cannabis intervention for young adults with psychosis achieved 92% completion and universal recommendation, supporting its feasibility for a larger efficacy trial.
CBD reduced schizophrenia-like symptoms in animals through two pathways: reducing neuroinflammation and modulating serotonin-MAPK signaling.
ABCD Study analysis of 11,854 children finding prenatal cannabis exposure associated with 58% higher odds of hallucinatory-like psychotic experiences, distinct from genetically-driven paranoid symptoms.
Expert commentary urging caution about medical cannabis for adolescent Tourette syndrome, highlighting the gap between adult evidence and adolescent safety concerns.
Large ABCD Study finds prenatal cannabis exposure alters brain reward processing in children, with blunted striatal responses predicting psychotic-like experiences over 4 years of follow-up.
Case report of cannabis hyperemesis syndrome developing during psychiatric admission for drug-induced psychosis, highlighting diagnostic challenges and the need for multidisciplinary cannabis-related care.
Five-year study of 1,379 first-psychosis patients finds cannabis-related psychosis follows a more chronic course than expected for substance-induced conditions, challenging treatment assumptions.
In one inpatient psychosis sample, cannabis users had higher MoCA scores than non-users.
A case report describes a patient who attempted suicide after 28 days of paranoia triggered by heavy use of THC gummies and THC-A products, highlighting the dangers of cannabinoid labeling confusion.
People with psychosis increased their cannabis use by nearly 10 percentage points after recreational legalization — larger than general population increases — with the effect linked to retail store openings.
Meta-analysis of 7,515 patients found ~34% with cannabis-induced psychosis later developed schizophrenia spectrum disorder and ~11% developed bipolar disorder.
Prenatal THC in rats altered placental expression of genes previously linked to schizophrenia in human studies, with sex-specific effects and fetal growth restriction.
Interviews with 15 young people in first-episode psychosis treatment and 16 parents reveal both want non-judgmental cannabis conversations with good information, but struggle to understand each other.
Brain imaging shows cannabis use has opposite inflammation effects in healthy people (lower) versus psychosis patients (higher), and may block antipsychotic medication's brain effects in psychosis.
Swedish nationwide study found moderate antipsychotic doses most effective for preventing psychotic relapse after cannabis-induced psychosis — higher doses added no benefit.
Case report of a daily cannabis user who developed delusional infestation -- believing parasites were under his skin -- highlighting an unusual presentation of cannabis-associated psychosis.
Analysis of 988 schizophrenia patients found THC-positive individuals had 36% lower odds of metabolic syndrome, with significantly less central obesity.
Study links gray matter loss in Parkinson's psychosis to CB1 cannabinoid receptor brain distribution, suggesting the endocannabinoid system may play a role in these symptoms.
A JAMA Psychiatry meta-analysis of 35 trials (4,136 participants) found current psychological interventions provided no meaningful benefit for reducing substance use in people with schizophrenia, except for a small effect on nicotine, highlighting an urgent need for new treatment approaches.
Retrospective review of 200 first-episode psychosis patients at a Soweto hospital found 73.6% had substance use, with cannabis most common at 46% and substance-induced psychosis as the top diagnosis.
Large Kaiser study found adolescent cannabis use associated with significantly higher rates of psychotic, bipolar, depressive, and anxiety disorders diagnosed through age 25.
CBD matched amisulpride for treating acute schizophrenia with dramatically fewer side effects — working through a novel mechanism: enhancing the brain's own anandamide signaling rather than blocking dopamine.
The definitive 468-page review: strong evidence for chronic pain and psychosis risk, insufficient evidence for most other claims, and a call to remove research barriers.
Largest CBD-for-psychosis RCT: 88 patients, 6 weeks. CBD 1000mg/day significantly reduced positive symptoms with zero side effect burden.