Cited by 322Cannabis and Cannabinoid ResearchSchizophrenia research and treatmentSubstance Abuse Treatment and Outcomes

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Continued versus discontinued cannabis use in patients with psychosis: a systematic review and meta-analysis

Schoeler, Tabea, Monk, Anna, Sami, Musa B, Klamerus, Ewa, Foglia, Enrico, Brown, Ruth, Camuri, Giulia, Altamura, A Carlo, Murray, Robin, Bhattacharyya, Sagnik·2016·The Lancet Psychiatry

DOI 10.1016/s2215-0366(15)00363-6

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Abstract

Background Although the link between cannabis use and development of psychosis is well established, less is known about the effect of continued versus discontinued cannabis use after the onset of psychosis. We aimed to summarise available evidence focusing on the relationship between continued and discontinued cannabis use after onset of psychosis and its relapse. Methods In this systematic review and meta-analysis, we searched MEDLINE for articles published in any language from the database inception date up until April 21, 2015 that included a sample of patients with a pre-existing psychotic disorder with a follow-up duration of at least 6 months. We used a combination of search terms for describing cannabis, the outcome of interest (relapse of psychosis), and the study population. We excluded studies if continued cannabis use or discontinued cannabis use could not be established. We compared relapse outcomes between those who continued (CC) or discontinued (DC) cannabis use or were non-users (NC). We used summary data (individual patient data were not sought out) to estimate Cohen's d, which was entered into random effects models (REM) to compare CC with NC, CC with DC, and DC with NC. Meta-regression and sensitivity analyses were used to address the issue of heterogeneity. Findings Of 1903 citations identified, 24 studies (16 565 participants) met the inclusion criteria. Independent of the stage of illness, continued cannabis users had a greater increase in relapse of psychosis than did both non-users (dCC-NC=0·36, 95% CI 0·22-0·50, p<0·0001) and discontinued users (dCC-DC=0·28, 0·12-0·44, p=0·0005), as well as longer hospital admissions than non-users (dCC-NC=0·36, 0·13 to 0·58, p=0·02). By contrast, cannabis discontinuation was not associated with relapse (dDC-NC=0·02, -0·12 to 0·15; p=0·82). Meta-regression suggested greater effects of continued cannabis use than discontinued use on relapse (dCC-NC=0·36 vs dDC-NC=0·02, p=0·04), positive symptoms (dCC-NC=0·15 vs dDC-NC=-0·30, p=0·05) and level of functioning (dCC-NC=0·04 vs dDC-NC=-0·49, p=0·008) but not on negative symptoms (dCC-NC=-0·09 vs dDC-NC=-0·31, p=0·41). Interpretation Continued cannabis use after onset of psychosis predicts adverse outcome, including higher relapse rates, longer hospital admissions, and more severe positive symptoms than for individuals who discontinue cannabis use and those who are non-users. These findings point to reductions in cannabis use as a crucial interventional target to improve outcome in patients with psychosis. Funding UK National Institute of Health Research.

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“Introduction Cannabis use is a risk factor for psychosis (Colizzi & Bhattacharyya, 2020; Schoeler et al., 2016a, b).”
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Behind the heterogeneity in the long-term course of first-episode psychosis: Different psychotic symptom trajectories are associated with different patterns of cannabis and stimulant use
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“…(Rognli et al., 2023; Tikka and D'Souza, 2019), and have been linked to exacerbations of psychotic symptoms in persons with psychotic disorders (Brown et al., 2020; Hasan et al., 2020; San et al., 2013; Schoeler et al., 2016a), including treatment-compliant individuals (Levi et al., 2023).”
Background
ARAS recent onset acute phase psychosis survey, a prospective observational cohort of first episode psychosis in Iran—the cohort profile
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Exploring the relationship between recency and frequency of cannabis use and diminished expression and apathy as two dimensions of negative symptoms in first episode psychosis. A one-year follow-up study
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Is the effect of cognitive reserve in longitudinal outcomes in first-episode psychoses dependent on the use of cannabis?
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“, 2019), but it is important to consider moderating variables such as the amount and pattern of consumption (Schoeler et al., 2016), sex (AyesaArriola et al.”
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Non-Dependent and Dependent Daily Cannabis Users Differ in Mental Health but Not Prospective Memory Ability
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“…of use increased the risk of substance used disorders in later life, but, more importantly, that the precocity of use before the age of 15, was also related to delinquency, may pre-dispose to VB (Rioux et al., 2018; Schoeler et al., 2016b) and was a risk factor of VB in EPP (Moulin et al., 2020).”
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“…found that patients who continue to use cannabis, and in particular thosewho use daily high potency cannabis after their first episode of psychosis, show a longer time spent in hospital, have higher rates of psychosis relapse and show more severe psychotic symptoms (Schoeler et al., 2016).”
Background
Avatar Intervention in Virtual Reality for Cannabis Use Disorder in Individuals With Severe Mental Disorders: Results From a 1-Year, Single-Arm Clinical Trial
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Randomized Laboratory Study of Single-Dose Cannabis, Dronabinol, and Placebo in Patients With Schizophrenia and Cannabis Use Disorder
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Cannabis Use Cessation and the Risk of Psychotic Disorders: A Case–Control Analysis from the First Episode Case–Control EU-GEI WP2 Study: L’arrêt de l’utilisation du cannabis et le risque de troubles psychotiques: Une analyse cas-témoins tirée de l’étude cas-témoins EU-GEI WP2 centrée sur les premiers épisodes psychotiques
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Cannabinoids and Their Role in Chronic Pain Treatment: Current Concepts and a Comprehensive Review
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“, 2017) as well as the impact of substance abuse discontinuation on outcome (Lambert et al., 2005; Schoeler et al., 2016) , it is very important to assess this variable in such studies.”
Background
Comorbid Cannabis and Tobacco Use Disorders in Hospitalized Patients with Psychotic-Spectrum Disorders
Reeves, L. E., Gaudiano, B. A., Metrik, J., Holst, C. G., Morena, A., Sydnor, V. J., Weinstock, L. M., & Epstein-Lubow, G. P. (2018) · Journal of Dual Diagnosis · doi:10.1080/15504263.2018.1470359 · Cited by 6
“Similarly, cannabis users with psychosis have a greater number of relapses, longer hospital admissions, and more severe positive symptoms than nonusers (Schoeler et al., 2016); although other research suggests that they may have better social functioning (Leeson, Harrison, Ron, Barnes, & Joyce, 2012; Salyers & Mueser,…”
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Adolescent cannabis use disorders
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“5 to 13 years: patients who continued to use cannabis, compared with those who never used cannabis or discontinued use, had more psychosis relapses; continued cannabis users also had longer hospitalizations compared with nonusers.(9) Among young adults with recentonset psychosis, those with concurrent substance use, i…”
Background
Relapse in substance‐induced psychosis and associated risk factors. A Nationwide register‐linkage study from Sweden
Ellilä, V., Taipale, H. T., Tiihonen, J., Mittendorfer‐Rutz, E., & Niemelä, S. (2025) · Addiction · doi:10.1111/add.70014 · Cited by 5
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“43 However, 69.7% of the sample were re-diagnosed with CUD (F12.x) by the end of the follow-up, suggesting persistence of these diagnoses after CIP.”
Influential
Cannabis and psychosis
Li, S., Solmi, M., Myran, D. T., & Fabiano, N. (2025) · Canadian Medical Association Journal · doi:10.1503/cmaj.250659 · Cited by 5
The rising tide of drug-induced psychosis
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Exploration of cannabis use and polygenic risk scores on the psychotic symptom progression of a FEP cohort
Segura, À. G., Mané, A., Prohens, L., Rodríguez, N., Mezquida, G., Cuesta, M. J., Vieta, E., Amoretti, S., Lobo, A., González-Pinto, A. M., et al. (2023) · Psychiatry Research · doi:10.1016/j.psychres.2023.115249 · Cited by 5
“Cannabis has a remarkable effect on FEP development and outcome (Di Forti et al., 2019; Schoeler et al., 2016).”
Background
Genome-wide association studies of lifetime and frequency of cannabis use in 131,895 individuals
Thorpe, H. H. A., Fontanillas, P., Meredith, J. J., Jennings, M. V., Cupertino, R. B., Pakala, S. R., Elson, S. L., Khokhar, J. Y., Davis, L. K., Johnson, E. C., et al. (2025) · Molecular Psychiatry · doi:10.1038/s41380-025-03219-2 · Cited by 7
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“Few studies have evaluated whether individuals with schizophrenia or schizoaffective disorder who use cannabis differ from non-substance users in number of psychiatric hospitalizations and length of stay (Schoeler et al., 2016; Williams et al., 2019).”
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How to quit cannabis when you have a mental illness: study from the perspective of patients who have successfully quit
Bruins, J., Crutzen, S., Veling, W., & Castelein, S. (2023) · BJPsych Bulletin · doi:10.1192/bjb.2023.69 · Cited by 5
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The effect of non-medical cannabis retailer proximity on use of mental health services for psychotic disorders in Ontario, Canada
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“Cannabis use is associated with the earlier onset of schizophrenia (Donoghue et al., 2014), acute episodes of psychosis (Sideli et al., 2020), and a higher risk of relapse for people with existing psychotic disorders (Schoeler et al., 2016).”
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Correlation still does not imply causation – Authors' reply
Schoeler, T., Murray, R. M., & Bhattacharyya, S. (2016) · The Lancet Psychiatry · doi:10.1016/s2215-0366(16)30044-x · Cited by 5
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The Züri Can study: Can regulated cannabis sales promote lower-risk cannabis use? Mini-review and study protocol
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“(8) 20 conducted a meta-analysis to examine the effects of continued or discontinued cannabis use in 21 patients with psychosis.”
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Predictive impact of different acute cannabis intoxication effects with regard to abstinence motivation and cessation of use
Schnell, T. G., Grömm, C.-M., & Klöckner, N. (2023) · Scientific Reports · doi:10.1038/s41598-023-27592-6 · Cited by 4
Predictors of relapse and engagement in care one year after ending services in an urban safety net coordinated specialty care program for first episode psychosis
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Authors: Schoeler, T., Monk, A., Sami, M. B., Klamerus, E., Foglia, E., Brown, R., Camuri, G., Altamura, A. C., Murray, R., & Bhattacharyya, S.
Affiliations: King's College London (GB)
University of Milan (IT)
Corresponding author: Bhattacharyya, Sagnik
ORCID: Schoeler, Tabea
Monk, Anna
Sami, Musa B
Klamerus, Ewa
Murray, Robin
Bhattacharyya, Sagnik
Venue: The Lancet Psychiatry
Publisher: Elsevier BV
Published: 2016-03
Volume: 3
Issue: 3
Pages: 215-225
ISSN: 2215-0366 (ISSN-L)
DOI: 10.1016/s2215-0366(15)00363-6
OpenAlex: W2257957527
Cited by: 322
References: 90
Citations by year: 2026: 17 · 2025: 25 · 2024: 33 · 2023: 34 · 2022: 39 · 2021: 28 · 2020: 39 · 2019: 34 · 2018: 30 · 2017: 24 · 2016: 18
FWCI: 4.07
Type: journal article
Language: en
Open access: closed
Licence: www.elsevier.com/tdm/userlicense/1.0/ (tdm)
Locations: The Lancet Psychiatry (publishedVersion)
PubMed (publishedVersion)
UCL Discovery (University College London) (submittedVersion)
Research Portal (King's College London) (submittedVersion)
Funders: National Institute for Health and Care Research (NF-SI-0512-10110, NIHR-CS-011-001, RP-PG-0606-1049)
Medical Research Council (MR/J012149/1, MR/K013807/1)
Topics: Health Sciences › Medicine › Pharmacology (medical) › Cannabis and Cannabinoid Research
Health Sciences › Medicine › Psychiatry and Mental health › Schizophrenia research and treatment
Health Sciences › Medicine › Epidemiology › Substance Abuse Treatment and Outcomes
Keywords: cannabis use, psychosis, relapse, hospitalization, positive symptoms, functioning, schizophrenia, bipolar disorder, schizoaffective disorder, delusional disorder, cannabis harm reduction, relapse prevention
MeSH terms: Humans, Marijuana Smoking, Psychotic Disorders, Recurrence

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Continued versus discontinued cannabis use in patients with psychosis: a systematic review and meta-analysis

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