0
0
Ontario Study Reveals Rising Connection Between Cannabis Use Disorder and Schizophrenia
A recent study published in JAMA Network Open has found that cases of schizophrenia linked to cannabis use disorder (CUD) have nearly tripled over the past 17 years in Ontario, Canada. Researchers from ICES, The Ottawa Hospital, the University of Ottawa’s Department of Family Medicine, and the Bruyère Health Research Institute analyzed healthcare data to examine whether cannabis legalization has influenced the relationship between CUD and schizophrenia diagnoses.
Key Findings
- The proportion of new schizophrenia cases associated with CUD has risen from 4% before cannabis legalization to 10% post-legalization in Ontario.
- The study observed a 270% increase in hospital visits for CUD, from 1.3 per 1,000 people before legalization to 4.6 per 1,000 afterward.
- Among new schizophrenia cases, the percentage of individuals who had previously received hospital care for CUD rose from 7% to 16%.
- Researchers estimated that during the legalization period, 10% of new schizophrenia cases could have been prevented if individuals with severe CUD had stopped using cannabis. In men aged 14 to 24, that figure rose to 18%.
Study Scope and Methodology
The study included over 13.5 million Ontario residents aged 14 to 65 and tracked three policy periods: pre-legalization, post-liberalization of medical cannabis in 2015, and post-legalization of non-medical cannabis in 2018. The findings suggest a growing public health concern, particularly among younger males who appear most vulnerable to the risks associated with cannabis use.
Dr. Daniel Myran, lead researcher and Canada Research Chair in Social Accountability at the University of Ottawa, emphasized the significance of the findings, stating, “Regular cannabis use is strongly associated with an increased risk of schizophrenia, and one of the main areas of uncertainty surrounding cannabis legalization is whether there would be changes in the number of new cases of schizophrenia.” He added, “Our study highlights the growing public health challenge posed by increasingly high-potency cannabis and rising regular cannabis use.”
Ongoing Debate and Public Health Implications
While the study establishes a link between cannabis use disorder and schizophrenia, it does not definitively conclude that cannabis use directly causes schizophrenia. However, researchers stress that heavy cannabis use can exacerbate symptoms and worsen the prognosis for those already living with the disorder.
Dr. Myran and his team call for targeted prevention strategies, especially among young people, to mitigate potential risks. “The tripling of schizophrenia cases associated with cannabis use disorder over the past 17 years and rising cases of psychosis underscores the urgent need for prevention efforts,” he stated.
Disclaimer
This article is based on research findings and does not constitute medical advice. The association between cannabis use disorder and schizophrenia is an area of ongoing study, and individual risk factors may vary. Readers are encouraged to consult healthcare professionals for personalized guidance regarding cannabis use and mental health.
For further details, the full study can be accessed in JAMA Network Open: DOI: 10.1001/jamanetworkopen.2024.57868.
