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Continued versus discontinued cannabis use in patients with psychosis: a systematic review and meta-analysis
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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“A meta-analysis of longitudinal studies [54] found that continued cannabis use in people with psychosis is associated with an increased risk of relapse to psychosis and with longer hospital stays than in non-users [55].”
From Cannabis, cannabinoids and health: a review of evidence on risks and medical benefits (2025) · cites this paper as [54]
In the citing paper
“A meta-analysis of longitudinal studies [54] found that continued cannabis use in people with psychosis is associated with an increased risk of relapse to psychosis and with longer hospital stays than in non-users [55].”
From Cannabis, cannabinoids and health: a review of evidence on risks and medical benefits (2025) · cites this paper as [54]
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Self-citationAdverse effects of heavy cannabis use: Even plants can harm the brain
Sideli, L., Trotta, G., Spinazzola, E., La Cascia, C., & Di Forti, M. (2021) · Pain · doi:10.1097/j.pain.0000000000001963 · Cited by 36
“Adverse effect Participants Studies Main findings Estimate Psychosis Marconi et al.18 66,816 individuals from 10 studies Random-effects meta-analysis on risk of psychosis High levels of cannabis use increase the risk of psychotic outcomes with a dose–response relationship OR 5 3.9, 95% CI [2.84-5.34] Large et al.77 81…”
BackgroundInfluentialMerritt, K., Pérez‐Iglesias, R., Sendt, K.-V., Arvanitis, A., Jauhar, S., Pepper, F., Barker, G. J., Glenthoj, B. Y., Arango, C., Lewis, S. W., et al. (2019) · Schizophrenia · doi:10.1038/s41537-019-0080-1 · Cited by 36
A Review of Cases of Marijuana and Violence
Miller, N. S., Ipeku, R., & Oberbarnscheidt, T. (2020) · International Journal of Environmental Research and Public Health · doi:10.3390/ijerph17051578 · Cited by 36
“These kinds of behaviors suggest that he was suffering from psychosis and paranoia since he was in the delusion that his acts would contribute to the Japanese society and the world [18,19].”
BackgroundSabé, M., Zhao, N., & Kaiser, S. (2020) · Neuroscience & Biobehavioral Reviews · doi:10.1016/j.neubiorev.2020.07.007 · Cited by 36
“Some evidence comes from a meta-analysis of longitudinal studies that showed a small trend-level effect, suggesting that cannabis discontinuers show less severe negative symptoms than continuous users and nonusers (Schoeler et al., 2016).”
InfluentialThe effects of cannabis use on salience attribution: a systematic review
Wijayendran, S. B., O’Neill, A., & Bhattacharyya, S. (2016) · Acta Neuropsychiatrica · doi:10.1017/neu.2016.58 · Cited by 36
“Inclusion criteria for the studies required that they were as follows: (1) studies of healthy humans; (2) investigating the acute or long-term effects of cannabis use, or effects of acute administration of THC; (3) measuring salience processing; (4) magnetic resonance imaging (MRI) studies.”
BackgroundSelf-citationPossible therapeutic applications of cannabis in the neuropsychopharmacology field
Fernández‐Ruíz, J., Galve‐Roperh, I., Sagredo, O., & Guzmán, M. (2020) · European Neuropsychopharmacology · doi:10.1016/j.euroneuro.2020.01.013 · Cited by 35
Cannabinoids, reward processing, and psychosis
Gunasekera, B., Diederen, K. M. J., & Bhattacharyya, S. (2021) · Psychopharmacology · doi:10.1007/s00213-021-05801-2 · Cited by 35
Self-citationEmsley, R., Asmal, L., Rubio, J. M., Correll, C. U., & Kane, J. M. (2020) · Schizophrenia Research · doi:10.1016/j.schres.2019.11.025 · Cited by 41
Gonçalves‐Pinho, M., Bragança, M., & Freitas, A. (2019) · International Journal of Methods in Psychiatric Research · doi:10.1002/mpr.1813 · Cited by 34
“Continued CU not only might play a role on the first psychotic event but also affects negatively the prognosis of a patient after the first episode of psychosis, increasing the relapse rate (Schoeler et al., 2016).”
BackgroundArgote, M., Sescousse, G., Brunelin, J., Baudin, G., Schaub, M. P., Rabin, R. A., Schnell, T. G., Ringen, P. A., Andreassen, O. A., Addington, J., et al. (2023) · EClinicalMedicine · doi:10.1016/j.eclinm.2023.102199 · Cited by 34
Livne, O., Shmulewitz, D., Sarvet, A. L., Wall, M. M., & Hasin, D. S. (2021) · American Journal of Psychiatry · doi:10.1176/appi.ajp.2021.21010073 · Cited by 35
Arranz, S., Monferrer, N., Algora, M. J., Cabezas, Á., Solé, M., Vilella, E., Labad, J., & Sánchez‐Gistau, V. (2018) · Schizophrenia Research · doi:10.1016/j.schres.2018.04.040 · Cited by 30
Setién‐Suero, E., Neergaard, K. D., de la Foz, V. O., Suárez‐Pinilla, P., Martínez‐García, O., Crespo‐Facorro, B., & Ayesa‐Arriola, R. (2019) · Acta Psychiatrica Scandinavica · doi:10.1111/acps.13081 · Cited by 30
“Retrospective studies have described a high prevalence of consumption among patients with a first psychotic episode (FEP) (7), a harmful effect of cannabis on disease prognosis (8) combined with more severe symptoms (9, 10) and higher relapse rates (11).”
BackgroundGroening, J. M., Denton, E., Parvaiz, R., Brunet, D. L., von Daniken, A., Shi, Y., & Bhattacharyya, S. (2023) · Psychiatry Research · doi:10.1016/j.psychres.2023.115626 · Cited by 36
“The meta-analysis by Schoeler et al. (2016) suggested that continued cannabis users experienced higher positive symptoms compared to non-users (see Fig.”
BackgroundMethodInfluentialSelf-citationColizzi, M., McGuire, P. K., Giampietro, V., Williams, S., Brammer, M. J., & Bhattacharyya, S. (2018) · European Neuropsychopharmacology · doi:10.1016/j.euroneuro.2018.04.003 · Cited by 28
Self-citationAthanassiou, M., Dumais, A., Gnanhoue, G., Abdel-Baki, A., Jutras-Aswad, D., & Potvin, S. (2021) · Expert Review of Neurotherapeutics · doi:10.1080/14737175.2021.1942845 · Cited by 29
“Crossreferencing of previous systematic reviews [31,44,45] on the”
BackgroundAppiah‐Kusi, E., Wilson, R., Colizzi, M., Foglia, E., Klamerus, E., Caldwell, A., Bossong, M. G., McGuire, P. K., & Bhattacharyya, S. (2019) · Psychological Medicine · doi:10.1017/s0033291719001946 · Cited by 26
“Introduction Independent of evidence associating cannabis use and onset and relapse of psychosis (Moore et al., 2007; Schoeler et al., 2016a, 2016b, 2016c; Sami and Bhattacharyya, 2018), evidence has also been accumulating regarding alterations in components of the eCB system in patients with…”
BackgroundSelf-citationSchoeler, T., Petros, N., Forti, M. D., Klamerus, E., Foglia, E., Murray, R. M., & Bhattacharyya, S. (2017) · Psychiatry Research · doi:10.1016/j.psychres.2017.05.009 · Cited by 26
“Cannabis users were classified based on their pattern of use following onset, depending on continuity and type (hash-like vs. skunk-like) (Di Forti et al., 2014; Schoeler et al., 2016) of cannabis use.”
BackgroundMethodResultInfluentialSelf-citation"Considerations for the Use of Medical Cannabis: An Overview of Benefits and Harms"
Shakya, D. R. (2021) · Biomedical Journal of Scientific & Technical Research · doi:10.26717/bjstr.2021.36.005886 · Cited by 8
“, increased relapserate, prolonged hospital-stay, severe positive symptoms [30].”
BackgroundSami, M. B., Notley, C. J., Kouimtsidis, C., Lynskey, M. T., & Bhattacharyya, S. (2018) · Psychological Medicine · doi:10.1017/s0033291718000569 · Cited by 25
“…and independent evidence that continued cannabis use is associated with greater risk of relapse in those with a pre-existing psychotic disorder (Schoeler et al. 2016a, b) and that this association is more likely than not to reflect a causal effect of continued cannabis use on outcome (Schoeler…”
BackgroundMethodSelf-citationMarino, L. A., Scodes, J. M., Richkin, T., Alves-Bradford, J.-M. E., Nossel, I. R., Wall, M. M., & Dixon, L. B. (2020) · Schizophrenia Research · doi:10.1016/j.schres.2020.05.035 · Cited by 25
Fischer, B., Hall, W., Fidalgo, T. M., Hoch, E., Foll, B. L., Medina‐Mora, M. E., Reimer, J., Tibbo, P. G., & Jutras‐Aswad, D. (2023) · Journal of Dual Diagnosis · doi:10.1080/15504263.2023.2226588 · Cited by 27
Rabin, R. A., Kozak, K., Zakzanis, K. K., Remington, G. J., & George, T. P. (2017) · Schizophrenia Research · doi:10.1016/j.schres.2017.03.010 · Cited by 25
“This effect was not present in patients who discontinued cannabis (Schoeler et al., 2016).”
BackgroundThomsen, K. R., Thylstrup, B., Pedersen, M. M., Pedersen, M. U., Simonsen, E. H., & Hesse, M. (2017) · Schizophrenia Research · doi:10.1016/j.schres.2017.09.026 · Cited by 25
“…causal links between cannabis use and exacerbation of positive symptoms (D'Souza et al., 2009; Morrison et al., 2009), and recent studies suggest that this link may be particularly relevant for use of high-potency cannabis (Di Forti et al., 2015; Iseger and Bossong, 2015; Schoeler et al., 2016b).”
InfluentialRains, L. S., Marston, L., Hinton, M., Marwaha, S., Craig, T., Fowler, D. G., King, M., Omar, R., McCrone, P., Spencer, J., et al. (2019) · BMC Medicine · doi:10.1186/s12916-019-1395-5 · Cited by 25
Johnson, S., Rains, L. S., Marwaha, S., Strang, J., Craig, T., Weaver, T. D., McCrone, P., King, M., Fowler, D. G., Pilling, S., et al. (2019) · Health Technology Assessment · doi:10.3310/hta23450 · Cited by 28
Rup, J., Freeman, T. P., Perlman, C. M., & Hammond, D. G. (2022) · Substance Use & Misuse · doi:10.1080/10826084.2022.2034872 · Cited by 24
“For example, evidence has shown an increased risk of relapse to psychosis and longer hospital admissions following continued cannabis use after onset of psychosis (Schoeler et al., 2016).”
BackgroundBlest‐Hopley, G., O’Neill, A., Wilson, R. P., Giampietro, V., & Bhattacharyya, S. (2019) · Psychopharmacology · doi:10.1007/s00213-019-05407-9 · Cited by 25
Self-citationMurray, R. M., Correll, C. U., Reynolds, G. P., & Taylor, D. M. (2017) · Therapeutic Advances in Psychopharmacology · doi:10.1177/2045125317693200 · Cited by 23
Self-citationKansagara, D. L., Terry, G. E., Ayers, C. K., & D'Souza, D. (2026) · JAMA Internal Medicine · doi:10.1001/jamainternmed.2025.8215 · Cited by 23
Early onset of cannabis use and violent behavior in psychosis
Moulin, V., Alameda, L., Framorando, D., Baumann, P.-S., Gholam, M., Gasser, J., Kim, Q., & Conus, P. (2020) · European Psychiatry · doi:10.1192/j.eurpsy.2020.71 · Cited by 22
“Cannabis is themostwidely used illicit recreational drug amongyoung people (18–25years) [1] and in patients with psychosis [1,2].”
BackgroundPrakash, J., Chatterjee, K., Srivastava, K., & Chauhan, V. S. (2021) · Industrial Psychiatry Journal · doi:10.4103/ipj.ipj_38_21 · Cited by 27
Current Cannabidiol Safety: A Review
Singh, C., Rao, K., Yadav, N., Vashist, Y., Chugh, P., Bansal, N., & Minocha, N. (2022) · Current Drug Safety · doi:10.2174/1574886317666220902100511 · Cited by 22
Colizzi, M., Weltens, N., McGuire, P. K., Oudenhove, L. V., & Bhattacharyya, S. (2019) · Brain Sciences · doi:10.3390/brainsci9040093 · Cited by 21
Self-citationBlest‐Hopley, G., O’Neill, A., Wilson, R. P., Giampietro, V., Lythgoe, D. J., Egerton, A., & Bhattacharyya, S. (2019) · Addiction Biology · doi:10.1111/adb.12827 · Cited by 22
Self-citationCorrelation still does not imply causation
Ksir, C. J., & Hart, C. L. (2016) · The Lancet Psychiatry · doi:10.1016/s2215-0366(16)30005-0 · Cited by 21
Kansagara, D. L., Hill, K. P., Yost, J., Humphrey, L. L., Shaw, B., Obley, A. J., Haeme, R., Akl, E. A., Qaseem, A., Humphrey, L. L., et al. (2025) · Annals of Internal Medicine · doi:10.7326/annals-24-03319 · Cited by 20
Levi, L. W., Haim, M. B., Rossum, I. W.-V., Davidson, M. L., Leucht, S., Fleischhacker, W. W., Park, J., Davis, J. M., Kahn, R. S., & Weiser, M. (2023) · Schizophrenia Bulletin · doi:10.1093/schbul/sbad033 · Cited by 20
Reid, S. W., & Bhattacharyya, S. (2019) · Psychiatry Research · doi:10.1016/j.psychres.2019.112523 · Cited by 20
Self-citation
Metadata
- 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
- Venue
- The Lancet Psychiatry
- Publisher
- Elsevier BV
- Published
- 2016-03
- Volume
- 3
- Issue
- 3
- Pages
- 215-225
- ISSN
- 2215-0366 (ISSN-L)
- 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
- 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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