New Study: Impact of non-medical cannabis legalization with market restrictions on health service use and incident cases of psychotic disorder in Ontario, Canada

A team of researchers led by Kelly Anderson with Rebecca Rodrigues, Britney Le, Maliha Mamun, Suzanne Archie, Jordan Edwards, Tara Elton-Marshall, Jason Gilliland, Daniel Thomas Myran, Lena Palaniyappan, Christopher Perlman, Jamie Seabrook, Robin Murray, and Salimah Shariff recently published an article entitled: “Impact of non-medical cannabis legalization with market restrictions on health service use and incident cases of psychotic disorder in Ontario, Canada.”

Cannabis is a risk factor in the onset and persistence of psychotic disorders. There is concern that non-medical cannabis legalization in Canada may have population-level impacts on psychotic disorders. The researchers sought to examine changes in health service use and incident cases of psychotic disorder following cannabis legalization, during a period of tight restrictions on retail stores and product types.

The researchers conducted a cross-sectional interrupted time-series analysis using linked population-based health administrative data from Ontario (Canada) from January 2014 to March 2020. They identified psychosis-related outpatient visits, emergency department visits, hospitalizations, and inpatient length of stay, as well as incident cases of psychotic disorders, among people aged 14 to 60 years.

The researchers did not find evidence of increases in health service use or incident cases of psychotic disorders over the short-term (17 month) period following cannabis legalization. However, they found clear increasing trends in health service use and incident cases of substance-induced psychotic disorders over the entire observation window (2014–2020).

The findings suggest that the initial period of tight market restriction following legalization of non-medical cannabis was not associated with an increase in health service use or frequency of psychotic disorders. A longer post-legalization observation period, which includes expansion of the commercial cannabis market, is needed to fully understand the population-level impacts of non-medical cannabis legalization; thus, it would be premature to conclude that the legalization of non-medical cannabis did not lead to increases in health service use and incident cases of psychotic disorder.

Citation: Kelly Anderson, Rebecca Rodrigues, Britney Le, Maliha Mamun, Suzanne Archie, Jordan Edwards, Tara Elton-Marshall, Jason Gilliland, Daniel Thomas Myran, Lena Palaniyappan, Christopher Perlman, Jamie Seabrook, Robin Murray, and Salimah Shariff. “Impact of non-medical cannabis legalization with market restrictions on health service use and incident cases of psychotic disorder in Ontario, Canada.” International Journal of Drug Policy 123 (2024); https://doi.org/10.1016/j.drugpo.2023.104285

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