Legalizing marijuana is “not associated with an increase in health service use or frequency of psychotic disorders”, according to a new study.
The study was published in the International Journal of Drug Policy, and it was conducted by researchers at Western University, McMaster University, the University of Ottawa, the University of Toronto, McGill University, Brescia University College and King’s College London.
“There is concern that non-medical cannabis legalization in Canada may have population-level impacts on psychotic disorders”, states the study’s abstract. “We 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.”
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.
“We 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”, states the study. “However, we found clear increasing trends in health service use and incident cases of substance-induced psychotic disorders over the entire observation window (2014–2020).”
In other words, psychotic disorders did increase between 2014 and 2020, but marijuana legalization does not appear to have had any impact on those rising numbers.
Our 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.
