Substance-Induced Psychosis Tied to Schizophrenia Risk


Individuals who visited the ER for substance-induced psychosis had a 160% greater risk of developing a schizophrenia spectrum disorder (SSD) compared with the general population, new research shows. Three years after an initial ER visit, 18.5% of those with substance-induced psychosis were diagnosed with an SSD. Cannabis-induced psychosis was associated with the greatest risk.


  • In this retrospective, population-based cohort study, investigators evaluated the risk of transition to a diagnosis of SSD for individuals with an ER visit for substance use vs the general population.

  • Investigators at The Ottawa Hospital and the Institute for Clinical Evaluative Sciences in Ontario analyzed data from six linked databases containing health information on nearly 10 million Ontario residents aged 14 to 65 years eligible for medical coverage.

  • Investigators collected the health data between January 2008 and March 2022 on residents with substance use-related ER visits with, and without, psychosis.


  • There were nearly 408,000 individuals with an ER visit for substance use, of which 13,800 (3.4%) of the visits were for substance-induced psychosis.

  • Individuals with substance-induced psychosis were at a 163-fold (age- and sex-adjusted hazard ratio [aHR], 163.2; 95% CI, 156.1 – 170.5) increased risk of transitioning to an SSD, relative to the general population (3-year risk, 18.5% vs 0.1%).

  • Individuals with an ER visit for substance use without psychosis had a lower relative risk of transitioning (aHR, 9.8; 95% CI, 9.5 – 10.2; 3-year risk, 1.4%), but incurred more than three times the absolute number of transitions (9969 vs 3029).

  • ER visits related to cannabis use had the highest transition risk among visits with psychosis (aHR, 241.6; 95% CI, 225.5 – 258.9) and the third-highest risk among visits without psychosis (aHR, 14.3; 95% CI, 13.5 – 15.2).

  • Younger age and male sex were associated with a higher risk of transition, and the risk of male sex was greater in younger compared with older individuals, particularly for cannabis use.


“Primary prevention efforts aimed at reducing substance use and substance use disorders could substantially reduce the population-level burden of chronic psychoses,” the investigators write. “Our findings also highlight the need for targeted secondary prevention providing early intervention and reducing substance use in the highest-risk groups, which may delay or prevent transition to schizophrenia spectrum disorders.”


Daniel T. Myran, MD, MPH, of the Ottawa Hospital Research Institute led the study, which was funded by the Canadian Institutes of Health Research and the University of Ottawa department of family medicine. The study was published online September 27 in JAMA Psychiatry.


Investigators did not have access to detailed data on substance-related outpatient visits or patterns of substance use, which could provide additional prognostic information.


Myran reported receiving grants from the Canadian Institutes of Health Research during the conduct of the study. Solmi reported receiving honoraria for participation on advisory boards or presentations from AbbVie, Angelini, Lundbeck, and Otsuka outside the submitted work. The remaining authors have disclosed no relevant financial relationships.

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