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Increased Risk of Schizophrenia in Patients With Substance Use-Related ED Visits
Emergency department (ED) visits for substance use, both with and without psychosis, were associated with an increased risk of developing schizophrenia spectrum disorder within 3 years, according to a retrospective cohort study published in JAMA Psychiatry.
“Our findings demonstrate an important increase in risk of being diagnosed with schizophrenia after an episode of substance-induced psychosis or substance use without psychosis – 163 times and 10 times higher than the background risk in the general population,” said lead author Daniel T. Myran, MD, MPH, Ottawa Hospital Research Institute, Bruyère Research Institute, and University of Ottawa, in Ontario, Canada.
The population-based study included 9.8 million people, aged 14 to 65 years and without a psychosis history, in Ontario, Canada. Between January 2008 and March 2022, 407,737 individuals had an ED visit for substance use. Substance-induced psychosis was involved in 3.4% of the ED visits.
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The risk of transitioning to schizophrenia spectrum disorder over 3 years was 18.5% in patients with an ED visit for substance-induced psychosis and 1.4% in patients with an ED visit for substance use without psychosis, according to the study. The comparative risk in the general population was 0.1%.
“Although substance-induced psychoses had a greater relative transition risk, substance use without psychosis was far more prevalent and resulted in a greater absolute number of transitions,” researchers reported.
Specifically, a total 9969 transitions to schizophrenia occurred among patients with an ED visit for substance use without psychosis and 3029 transitions occurred among those with substance-induced psychosis.
Cannabis posed the highest transition risk for patients with substance-induced psychosis; 26% of patients developed schizophrenia within 3 years, the research team reported. For patients without psychosis, amphetamine use — predominantly methamphetamine or crystal meth — posed the highest risk; 3.7% developed schizophrenia within 3 years.
Younger age and male sex were associated with a higher transition risk. More than 40% of males between 14 and 24 years with cannabis-induced psychosis were later diagnosed with schizophrenia, the study found.
“The high risk of cannabis use, particularly for young men, has important implications for public education and policies given global trends of increasing cannabis use and interest in the legalization of cannabis,” Dr Myran said.
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