Changes in Symptoms of Cannabis Use Disorder of Ontario Youth Across the COVID-19 Pandemic: A Longitudinal Cohort Study

Background: Cannabis use increased among youth during the COVID-19 pandemic. However, there is a lack of research examining whether there were lasting changes in cannabis use and, in particular, problematic cannabis use, across the pandemic. This is particularly important to examine among young adults because problematic cannabis use is associated with a greater likelihood of impaired neurodevelopment and adverse health outcomes. Methods: The study was a longitudinal cohort survey of Canadian youth (n = 1579; 55% female; mean age 22 years) aged 16 to 30 residing in Ontario who reported cannabis use in the past 3 months. Respondents completed online questionnaires regarding their cannabis use once in 2022 and again in 2023. Linear regression examined the association between reporting increased cannabis use during the pandemic and changes in symptoms of cannabis use disorder (CUD) (measured by the Cannabis Use Disorder Identification Test–Revised [CUDIT-R]). Models were adjusted for sociodemographic factors and psychological distress. Results: Linear regression indicated that increased cannabis use in response to the COVID-19 pandemic was significantly associated with increased CUDIT-R scores across survey waves (β: 1.49; 95% CI: 0.99, 2.00). The association between increased cannabis use and changes in symptoms of CUD was stronger for younger than older participants ( P = .04). Conclusion: The COVID-19 pandemic was associated with increasing symptoms of CUD, particularly among youth, even 3 years after it was initially declared. This study highlights the importance of addressing the ongoing impacts of the COVID-19 pandemic and developing strategies to prevent hazardous substance use in future health crises.