A study of data from pre and post-cannabis legalisation in Canada has found no increase in admissions to hospitals for cannabis-related episodes of psychosis.
The relationship between cannabis use and episodes of psychosis is a contentious issue that is often raised by opponents of legalisation. Results from previous studies have been mixed, with some finding evidence to suggest cannabis use, particularly in adolescence, can be a cause of psychotic episodes, and others finding no association between the two.
The present study was published in The Canadian Journal of Psychiatry in February 2024 and used data collected from the three emergency departments (EDs) in Quebec City. The number of admissions for psychosis where evidence of cannabis use was present was compared by researchers to the number of admissions in the 12 months following legalisation.
Only admissions from adults aged 18 years and above were included in the data, and evidence of cannabis use was obtained from the patient’s medical records and included results of urine tests as well as clinical notes.
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