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Cannabis

A widely used plant studied across pain, anxiety, sleep, and its interactions with mental health.

State of the evidence

Synthesized

Synthesized from 25 studies in the library · AI-generated, grounded in the abstracts below

Found by searching the library for Cannabis, marijuana, THC, cannabidiol, CBD, then ranked by relevance.

The research indicates that cannabis use is associated with an increased risk of psychotic symptoms and disorders, with controlled laboratory studies showing that cannabinoid agonists can transiently produce schizophrenia-like symptoms in healthy individuals and exacerbate symptoms in those with schizophrenia. However, the evidence is complicated by high rates of polysubstance use, and the long-term effects and mechanisms remain areas of active investigation. The findings are consistent across multiple study types, but the overall confidence is limited by the prevalence of observational designs and the confounding factor of co-use with other substances.

Evidence by study

Direction is which way each study's own result points, not our rating of the study.

What the directions mean
Supports:
the study found the intervention worked, or its hypothesis held.
Opposes:
it found the opposite, no benefit or a harm.
No effect:
no significant difference either way.
Mixed:
effects in both directions within the same study.
Unclear:
the abstract does not report a direction.
Cannabis sativa: A comprehensive ethnopharmacological review of a medicinal plant with a long history. 2018
Unclear

This comprehensive review describes the ethnopharmacology and pharmacology of Cannabis sativa, including its key psychoactive constituent THC and the endocannabinoid system, but does not directly assess clinical outcomes.

review

Human Laboratory Studies on Cannabinoids and Psychosis. 2016
Supports

Controlled laboratory studies demonstrate that cannabinoid agonists produce positive, negative, and cognitive symptoms resembling schizophrenia in healthy subjects and transiently exacerbate symptoms in individuals with schizophrenia, challenging the self-medication hypothesis.

review of RCTs

Drug-Induced Psychosis: How to Avoid Star Gazing in Schizophrenia Research by Looking at More Obvious Sources of Light 2011
Supports

This review discusses evidence that cannabis, among other drugs, can induce schizophrenia-like psychosis, contributing to the view that liability to psychosis is continuously distributed in the population.

review

Substance-Induced Psychoses: An Updated Literature Review 2021
Supports

This updated review finds that abuse of cannabis plays a significant role in increasing the incidence of episodes resembling a psychotic disorder, though it notes the difficulty in distinguishing induced psychosis from primary psychotic disorders due to frequent comorbidity.

narrative review

Functional recovery trajectories in cannabis-induced first-episode psychosis: The role of dissociative symptoms in the discrepancy between symptomatic improvement and functional outcomes. 2026
Supports

In a 24-month prospective study of 72 patients with cannabis-induced first-episode psychosis, continued cannabis use was associated with worse functional outcomes, with dissociative symptoms mediating 35% of this effect.

prospective cohort Sample size: 72

Drug models of schizophrenia. 2015
Unclear

This review selectively examines findings from cannabinoid pharmacological drug models to evaluate their similarity to schizophrenia, but does not provide a specific directional finding on cannabis itself.

review

A Clinical and Metabolic Study of Acute Intoxication with Cannabis Sativa and its Role in the Model Psychoses 1958
Unclear

This historical study describes the effects of oral cannabis administration and its potential as a model psychosis, but the abstract does not provide specific quantitative results.

clinical study

The confounding problem of polydrug use in recreational ecstasy/MDMA users: a brief overview 2006
Mixed

This review notes that cannabis use is a well-recognized risk factor for neuropsychiatric disorders and contributes to psychological problems in ecstasy users, but also that cannabinoids have neuroprotective actions that may partially block MDMA-induced neurotoxicity in animals.

review

MDMA in humans: factors which affect the neuropsychobiological profiles of recreational ecstasy users, the integrative role of bioenergetic stress 2006
Mixed

This review states that around 90-95% of ecstasy/MDMA users also take cannabis, which can independently contribute to adverse neuropsychobiological profiles, though acute co-use may be interactive rather than additive due to cannabis's relaxant and hypothermic properties.

review

Impaired cognitive performance in drug free users of recreational ecstasy (MDMA) 2000
Supports

This study raises concern that use of ecstasy, possibly in conjunction with cannabis, may lead to cognitive decline in otherwise healthy young people, suggesting an impairment of working memory.

observational

Patterns of simultaneous polysubstance use in drug using university students 2006
Unclear

This study found that cannabis is frequently co-administered with alcohol, tobacco, and other substances, but patterns of cannabis use were not systematically related to other substances administered.

observational Sample size: 149

Here today, gone tomorrow…and back again? A review of herbal marijuana alternatives (K2, Spice), synthetic cathinones (bath salts), kratom, Salvia divinorum, methoxetamine, and piperazines. 2012
Unclear

This review discusses synthetic cannabinoids (e.g., K2, Spice) as herbal marijuana alternatives, noting their adverse effects ranging from minimal to life-threatening, but does not directly address cannabis itself.

review

Interaction of drugs of abuse and maintenance treatments with human P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2). 2010
Unclear

This in vitro study found that THC inhibits human P-glycoprotein and breast cancer resistance protein in a concentration-dependent manner, suggesting potential drug-drug interactions, but does not assess clinical outcomes.

in vitro

Medicinal Plants with Psychoactive Properties: A Comprehensive Review 2026
Unclear

This review includes Cannabis sativa among 20 medicinal plants with psychoactive properties, noting its neuropharmacological activities through modulation of the endocannabinoid system, but does not provide specific clinical findings.

review

Cannabis Sativa, religion and society: Historical, medicinal, legal, and sacramental perspectives 2026
Unclear

This article examines the historical, medicinal, legal, and religious aspects of Cannabis sativa, but does not present empirical findings on health outcomes.

review

Prophylactic efficacy of cannabidiol and sodium nitroprusside in a ketamine model of schizophrenia: sex-dependent effects on positive-like and cognitive impairments 2026
Mixed

In a rodent model of schizophrenia, cannabidiol (CBD) combined with sodium nitroprusside showed prophylactic efficacy in preventing ketamine-induced positive-like and cognitive impairments, with sex-dependent effects, but CBD alone had limited efficacy.

preclinical (animal study)

Psychedelic-Assisted Psychotherapy for the Treatment of PTSD: A Systematic Review and Meta-Analysis 2026
No effect

In a meta-analysis of 11 RCTs for PTSD, a single cannabidiol trial showed no clear benefit, while MDMA-assisted psychotherapy showed a significant moderate-to-large reduction in PTSD symptom severity.

systematic review and meta-analysis Sample size: 358

Ayahuasca-Assisted Therapy for Addiction: Results from a Preliminary Observational Study in Canada 2013
Unclear

This study found that ayahuasca-assisted therapy was associated with improvements in factors related to problematic substance use, but does not directly address cannabis.

observational

Persisting Reductions in Cannabis, Opioid, and Stimulant Misuse After Naturalistic Psychedelic Use: An Online Survey 2020
Unclear

This survey found persisting reductions in cannabis, opioid, and stimulant misuse after naturalistic psychedelic use, but the cross-sectional design cannot determine causality.

cross-sectional survey

Standardised Mindfulness-Based Interventions in Healthcare: An Overview of Systematic Reviews and Meta-Analyses of RCTs 2015
Unclear

This review found that mindfulness-based interventions improved depressive symptoms, anxiety, stress, quality of life, and physical functioning, but does not address cannabis.

systematic review and meta-analysis Sample size: 8683

A cross-national comparison of nonmedical and medical use of psychedelic drugs in the international cannabis policy study. 2026
Unclear

This study estimated prevalence of psychedelic use and medical discussions, but does not directly address cannabis.

cross-sectional survey

The need for another tool: Australian healthcare professionals on the use of psilocybin for existential distress in people with cancer 2026
Unclear

This qualitative study explored healthcare professionals' attitudes toward psilocybin-assisted therapy for existential distress in cancer patients, but does not address cannabis.

qualitative Sample size: 11

Past-Year Psilocybin and Alcohol Co-Use: Associations With Mental Health Symptoms 2026
Unclear

This study found that individuals with past-year psilocybin and alcohol co-use had fewer depressive symptoms than those who used alcohol without psilocybin, but does not directly address cannabis.

cross-sectional survey Sample size: 2841

Attitudes of Mental Healthcare Professionals Towards the Use of Psychedelics in the Treatment of Substance Use Disorders: A Systematic Review 2026
Unclear

This systematic review found that mental healthcare professionals hold cautiously optimistic attitudes toward psychedelic-assisted therapy for substance use disorders, but does not directly address cannabis.

systematic review Sample size: 966

Spiritual health and healing in Ethiopia: A scoping review and thematic analysis of beliefs, practices, and gaps in healthcare integration 2026
Unclear

This scoping review maps spiritual health beliefs and practices in Ethiopia, but does not address cannabis.

scoping review

Points of agreement

  • Multiple reviews and controlled laboratory studies converge on the finding that cannabinoid agonists can induce transient psychotic-like symptoms in healthy individuals and exacerbate symptoms in those with schizophrenia.
  • Observational studies consistently report an association between cannabis use and increased risk of psychotic disorders, though causality is difficult to establish due to confounding factors.
  • The evidence suggests that cannabis use is a significant environmental factor in the development of psychosis, particularly in vulnerable individuals.

Conflicts

  • There is a conflict between the potential neuroprotective effects of cannabinoids (e.g., blocking MDMA-induced neurotoxicity in animal studies) and the observed adverse neuropsychiatric effects in human observational studies.
  • The role of cannabis in cognitive decline is debated, with some studies suggesting impairment while others note that effects may be confounded by polysubstance use.
  • The self-medication hypothesis for cannabis use in schizophrenia is challenged by laboratory studies showing exacerbation of symptoms, but observational data cannot fully rule it out.

Gaps

  • Long-term prospective studies with adequate control for polysubstance use are lacking, making it difficult to isolate the specific effects of cannabis on psychosis and cognition.
  • The durability of cannabis-induced psychotic symptoms and the long-term functional outcomes in patients with cannabis-induced psychosis are not well characterized.
  • There is a need for more research on the dose-response relationship and the differential effects of various cannabinoids (e.g., THC vs. CBD) on mental health outcomes.
  • The role of genetic vulnerability (e.g., COMT, DAT1 polymorphisms) in moderating the effects of cannabis on psychosis is underexplored in large-scale studies.
  • Most studies focus on acute or short-term effects; the long-term neurobiological and cognitive consequences of chronic cannabis use remain poorly understood.
Browse these studies in the library
How we analyze this

This synthesis reads the 15 most-cited and 10 most recent studies whose primary subject is Cannabis, up to 25 in all. The most-cited set anchors the established evidence, and the recent set surfaces work that is too new to have gathered citations yet.

A study qualifies only when Cannabis or a known alias appears in its title or keywords, so broad reviews that mention it only in passing are left out. Each study is read from its abstract, strongest evidence first, and the summary reports the direction of the results along with any conflicts and gaps.

Ask your own question in the Research Synthesis Tool

Latest monthly recap: June 2026 →

1,163 articles · 306 from the last two years · 3,613,849 participants across 550 studies reporting sample size

Common study designs

review 187 observational cohort 128 cross-sectional survey 67 randomized controlled trial 60 theoretical or philosophical paper 54

Research

Synthesize the evidence → Search all →

The subjective effects of △9-tetrahydrocannabinol: A systematic review and dose-response meta-regression.

Neuroscience and Biobehavioral Reviews September 1, 2026 Isabella Goodwin, Dominic Oliver, Edward Chesney et al.

A meta-analysis of 41 double-blind, placebo-controlled experiments involving 1,020 infrequent cannabis users found that acute THC administration increases feelings of high, anxiety, and tiredness, while decreasing alertness and contentedness, with no effect on calmness. Inhaled THC dose-dependently increased high and contentedness but decreased calmness, with greater consistency in high and contentedness at higher doses. On a 100-point scale, inhaling 5 mg THC increased high by 34.3 points, anxiety by 14.4, tiredness by 26.3, and calmness by 4.5, while decreasing alertness by 40.2 and contentedness by 71.0. Oral THC showed no significant subjective effects, though higher oral doses produced more consistent alertness. These findings can inform public health guidance on expected THC effects.

DOI: 10.1016/j.neubiorev.2026.106795 (opens in new tab) Full text (opens in new tab) Cannabis THC Meta-analysis Meta-regression +2

Functional recovery trajectories in cannabis-induced first-episode psychosis: The role of dissociative symptoms in the discrepancy between symptomatic improvement and functional outcomes.

Psychiatry Research September 1, 2026 Valerio Ricci, Andrea Paggi, Giovanni Martinotti et al.

In patients with cannabis-induced first-episode psychosis, dissociative symptoms—especially depersonalization and derealization—are strong independent predictors of poor functional recovery over 24 months. Among 72 patients, three recovery trajectories emerged: Rapid Recovery (34.7%, GAF +29.1 points), Gradual Recovery (40.3%, GAF +15.7 points), and Persistent Impairment (25.0%, GAF +4.7 points). A symptom-function discrepancy occurred in 31.9% of patients, where psychotic symptoms improved but functioning did not; these patients had higher baseline dissociation scores (33.8 vs. 18.1). Dissociation mediated 35% of cannabis's negative effect on functional outcomes. A high-risk subgroup (22%) with elevated dissociation, depression, and continued cannabis use showed minimal improvement despite treatment. Routine dissociation assessment and targeted interventions may improve outcomes.

DOI: 10.1016/j.psychres.2026.117240 (opens in new tab) Full text (opens in new tab) Cannabis-induced psychosis Depersonalization Dissociation First-episode psychosis +1

A cross-national comparison of nonmedical and medical use of psychedelic drugs in the international cannabis policy study.

The International journal on drug policy August 1, 2026 Myfanwy Graham, Yimin Ge, Rosalie Liccardo Pacula et al. 1 citation

An estimated 19% of adults in Canada, the United States, Australia, and New Zealand have used psilocybin, LSD, MDMA, or ketamine at some point in their lives. Psilocybin was the most commonly used substance, with lifetime use highest in Canada (16.3%), followed by the US (13.0%) and New Zealand (12.1%), and lowest in Australia (7.8%). Among those who had ever used a psychedelic, 10-20% had asked their medical provider about medical use, and over a third of past-year users reported experiencing an adverse health effect. Past-month use was low across all countries. Consumer interest in therapeutic use has outpaced clinical trials and therapeutic provisions, and many people use these substances outside regulated pathways, which may increase the risk of adverse events.

DOI: 10.1016/j.drugpo.2026.105348 (opens in new tab) Full text (opens in new tab) Adverse events Drug policy Nonmedical use Psychedelics

Cannabis, psychosis, and violence: case reports and comprehensive evidence review

Frontiers in Psychiatry July 21, 2026 Kenneth P. Finn, Robin Murray, Elizabeth Stuyt et al.

Cannabis use, especially high-potency products with THC concentrations above 10%, has been linked to rising psychosis cases from 1995 to 2010. Psychosis has multiple causes including genetics, childhood adversity, and drug use. This perspective argues that cannabis-associated violence deserves more attention, presenting high-profile media cases where THC was the only substance involved or cannabis use preceded psychosis and violence. Toxicology often fails to test for THC. The evolving evidence on cannabis, psychosis, and violence should inform medical screening, law enforcement, and policy.

DOI: 10.3389/fpsyt.2026.1824748 (opens in new tab) Full text (opens in new tab) Cannabis-induced psychosis Harm Violence

Disruption of Reelin signaling in a dual-hit mouse model of schizophrenia: impact of postnatal Δ9-tetrahydrocannabinol exposure in a maternal immune activation model

Translational Psychiatry July 16, 2026 Celia Martín-Cuevas, Víctor Darío Ramos‐Herrero, Álvaro Flores‐Martínez et al.

A dual-hit mouse model combining prenatal immune activation with adolescent THC exposure produces schizophrenia-relevant behavioral and brain changes, particularly in males. Social deficits and repetitive behaviors emerged, along with reduced cortical thickness and decreased dendritic spine density in the prefrontal cortex and hippocampus. Reelin signaling pathway alterations occurred in a sex-dependent manner: males showed reduced Reelin levels mainly after THC exposure alone, while females had general reductions across treatment groups. The number of Reelin-positive cells also decreased. Adolescent THC exposure appears to be a major driver of Reelin alterations, with prenatal immune activation potentially modulating this effect. The findings highlight complex, domain-specific interactions between environmental risk factors in schizophrenia-related processes.

DOI: 10.1038/s41398-026-04282-1 (opens in new tab) Full text (opens in new tab) Schizophrenia object-oriented programming Reelin Neuroscience Immune system +10

Prefrontal connectivity alterations and oscillatory dynamics in cannabis use disorder.

Biological Psychology July 9, 2026 Nattanon Bunrodchu, Ekkasit Kumarnsit, Wan Khairunizam Wan Ahmad et al.

Long-term cannabis use alters default mode network (DMN) dynamics and cross-frequency interactions in the brain. Resting-state EEG recordings from 23 participants with cannabis use disorder (CUD) and 23 healthy controls showed that delta-high gamma and beta-high gamma coupling in prefrontal regions distinguished CUD participants from controls, especially with eyes open. Frontal-parietal and frontal-temporal coherence was heightened during eye closure in CUD participants. A multilayer perceptron classifier using these multidimensional EEG features successfully differentiated cannabis users from controls, suggesting that altered DMN function and cross-frequency coupling are potential electrophysiological markers of long-term cannabis use.

DOI: 10.1016/j.biopsycho.2026.109344 (opens in new tab) Full text (opens in new tab) Cannabis Frontal cortical networks Multilayer perceptron Neural oscillations +1

Dynamic Brain States With Cannabis Intoxication: Beyond "More Is Better" in Interpreting Brain Connectivity.

Biol Psychiatry July 1, 2026

Cannabis intoxication does not simply increase or decrease brain connectivity; instead, it shifts the brain into more variable and less stable dynamic states. The findings indicate that intoxication leads to greater fluctuations in connectivity patterns over time, challenging the idea that more cannabis simply produces stronger effects. The authors suggest that the relationship between cannabis dose and brain connectivity is nonlinear, with different brain networks responding differently to intoxication.

DOI: 10.1016/j.biopsych.2026.05.005 (opens in new tab)

Cannabis Sativa, religion and society: Historical, medicinal, legal, and sacramental perspectives

Acta Theologica June 30, 2026 Norman Nyazema, Jo Nel

As cannabis decriminalization and legalization evolve globally, this article examines the relationship between Cannabis sativa and religion. It covers the plant's ancient origins, chemical structure, historical medicinal uses from ancient China to modern applications, and its criminalization, questioning the constitutionality of current legal frameworks. The article also explores cannabis's role in selected religions. The authors suggest future research, including a questionnaire to investigate how religious beliefs shape attitudes toward cannabis.

DOI: 10.38140/cq5s1148 (opens in new tab) Decriminalization Nexus standard Constitutionality Cannabis sativa +6

Cannabis use and glutamate across the psychosis spectrum: in vivo evidence from 7T proton magnetic resonance spectroscopy

Molecular Psychiatry June 27, 2026 David R. Roalf, Tyler M Moore, Jacquelyn Stifelman et al.

Cannabis use is linked to higher psychosis risk, and this study examined whether brain glutamate levels in the anterior cingulate cortex (ACC) relate to symptoms depending on cannabis use. Among 79 participants across the psychosis spectrum, higher ACC glutamate independently predicted greater positive and negative symptoms. However, in cannabis users, lower glutamate was associated with more positive symptoms. Psychosis patients who used cannabis had lower ACC glutamate, suggesting glutamatergic dysfunction may amplify symptom severity. The findings implicate ACC glutamate as a transdiagnostic correlate of symptom burden, especially in cannabis users with psychosis.

DOI: 10.1038/s41380-026-03705-1 (opens in new tab) Full text (opens in new tab) Glutamatergic Psychosis Glutamate receptor Effects of cannabis +8

Psychotic-like experiences and neurobehavioral reward processing in adolescents who use cannabis

PsyArXiv Preprints June 25, 2026

Adolescents who use cannabis and also report psychotic-like experiences show reduced motivation to work for rewards, especially when the effort required is low or medium. Higher cannabis use was linked to more psychotic-like experiences, but only in adolescents with elevated tissue iron signal (1/nT2*), a marker of dopamine-related brain activity, in the putamen and thalamus. The findings suggest that cannabis use during adolescence may alter reward processing and dopamine-related neurophysiology in ways that depend on vulnerability to psychosis.

DOI: osf:rsmun_v1 (opens in new tab) Full text (opens in new tab) Cannabis Adolescence Psychosis Reward effort +3

Clinical trials

All Cannabis trials →