New research conducted by the Bruyère Research Institute, University of Ottawa Department of Family Medicine, The Ottawa Hospital, and ICES sheds light on the correlation between cannabis use and the development of anxiety disorders. This study, which is the largest of its kind to date, involved over 12 million individuals in Ontario, Canada, spanning from 2008 to 2019. These individuals had no prior history of anxiety diagnosis or treatment. Published in The Lancet’s eClinical Medicine, the study utilized health record data from ICES to analyze the risk of anxiety disorder development among those who had visited the emergency department (ED) for cannabis use compared to the general population.
Key findings from the study include:
- New anxiety disorder risk: Within three years, 27.5% of individuals who visited the ED for cannabis use were diagnosed with a new anxiety disorder, in contrast to 5.6% of the general population—a 3.9-fold increased risk, even after adjusting for social factors and other mental health diagnoses.
- Severe or worsening anxiety disorder risk: Within three years, 12.3% of ED cannabis users had hospitalizations or ED visits for anxiety disorders, compared to 1.2% of the general population—a 3.7-fold increased risk after adjustments.
- Those whose ED visit was primarily due to cannabis had a 9.4-fold increased risk of hospitalization or ED visit for an anxiety disorder compared to the general population.
- Both men and women, across all age groups, showed elevated risk of developing new anxiety disorders after an ED visit for cannabis use. Notably, young adults (10-24 years) and men were at particularly heightened risk.
The study addresses ongoing debates about whether cannabis use contributes to the onset of anxiety disorders or if individuals use cannabis to self-medicate existing anxiety symptoms. While the findings suggest that cannabis use may exacerbate anxiety, they do not establish causality definitively.
Regardless of causality, the researchers advise against using cannabis to manage anxiety symptoms due to the lack of evidence supporting its efficacy. Additionally, cannabis use may delay access to evidence-based treatments and could potentially worsen anxiety symptoms significantly.