Prevalence of schizophrenia spectrum and bipolar disorder among patients with cannabis induced psychosis: a systematic review and meta-analysis

Javed, Mohammad Saad, El-Khoury, Rayane, Taha, Amr Ahmed and Reagu, Shuja Mohd 2026. Prevalence of schizophrenia spectrum and bipolar disorder among patients with cannabis induced psychosis: a systematic review and meta-analysis. BMC Psychiatry 26 (1) , 186. 10.1186/s12888-025-07382-2

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Abstract

Background: Distinguishing cannabis-induced psychosis from primary psychiatric disorders is difficult and has significant clinical and prognostic implications. Current treatment approaches lack standardized guidelines, potentially leading to the development of schizophrenia spectrum and bipolar disorder. This study systematically reviews the literature and provides a pooled prevalence of later developing these disorders following a cannabis-induced psychosis diagnosis. Methods: We systematically reviewed Medline, Embase, Web of Science, Google Scholar, and PsychInfo for studies reporting on a group of patients with cannabis-induced psychosis and subsequent diagnoses of schizophrenia spectrum disorder, bipolar disorder, or both. The search was conducted until January 1, 2025. A modified version of the Newcastle-Ottawa scale was used to assess study quality. Random-effects meta-analyses were conducted to calculate pooled mean prevalence. Random-effects meta-regressions were used to identify predictors of higher prevalence. Results: Our strategy identified 13 studies eligible for inclusion with a total population size of 7,515 which reported a total of 16 outcomes of interest. Among cannabis induced psychosis patients, 20% (95% CI:15.8–29.5%) later received a schizophrenia spectrum diagnosis, 5% (95% CI:2.7–6.9%) bipolar and 63% (95% CI:26.8–90.5%) unspecified (both). Compared to individuals receiving a later schizophrenia spectrum disorder diagnosis, patients were 76% less likely to develop bipolar disorder. Later diagnosis of an unspecified disorder showed an approximate 3 folds higher risk with an ARR of 2.52 (95% CI: 1.03–6.15) compared to schizophrenia spectrum disorder alone. Conclusions: Approximately one in five patients diagnosed with cannabis-induced psychosis will develop schizophrenia spectrum disorder, while one in twenty will be later diagnosed with bipolar disorder.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Schools > Medicine
Additional Information:	License information from Publisher: LICENSE 1: URL: http://creativecommons.org/licenses/by-nc-nd/4.0/, Type: open-access
Publisher:	BioMed Central
Date of First Compliant Deposit:	23 February 2026
Date of Acceptance:	26 August 2025
Last Modified:	23 Feb 2026 14:00
URI:	https://orca.cardiff.ac.uk/id/eprint/185129

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