Overall, the study highlights the urgent need for ongoing research into the long-term effects of cannabis policy on the prevalence of psychotic disorders.
A recent study has established a concerning link between Canada's cannabis legalization and a notable rise in schizophrenia cases associated with cannabis use disorder (CUD) in Ontario.
Analyzing electronic medical records from over 13.5 million Ontario residents between 2006 and 2022, the study found that new schizophrenia cases related to CUD nearly tripled following legalization.
The research specifically investigates the relationship between cannabis use disorder and schizophrenia in Canada, particularly after significant changes in cannabis policy.
Post-legalization, the number of individuals requiring hospital care for CUD surged by 270%, increasing from 1.3 to 4.6 per 1,000 people.
The population-attributable risk fraction (PARF) for CUD linked to schizophrenia rose dramatically from 3.7% before legalization to 10.3% during the legalization period, with young men aged 19-24 being particularly affected.
Among individuals diagnosed with CUD, 8.9% developed schizophrenia, a stark contrast to just 0.6% in the general population without CUD.
While the overall annual incidence of schizophrenia remained stable, the incidence of psychosis not otherwise specified (NOS) saw a significant increase of 83.7% after legalization.
The research raises alarms about the public health consequences of increased cannabis potency and usage, especially among younger populations.
Jodi Gilman from Massachusetts General Hospital emphasized the necessity for comprehensive epidemiological studies to evaluate the long-term mental health effects of cannabis legalization on vulnerable groups.
These findings underscore the critical need to consider the public health implications of cannabis legalization, particularly concerning mental health disorders.
Study investigator Daniel Myran cautioned that legalization does not mitigate the risks associated with cannabis use, similar to the dangers posed by legal substances like alcohol and tobacco.
