Summary: A decade-long analysis of roughly 35,000 Canadians shows a growing and concerning overlap between cannabis use and mental health problems. Between 2012 and 2022, as cannabis use became more common, rates of generalized anxiety disorder, major depressive episodes, and suicidality rose in parallel. The association strengthened over time, especially after legalization, with frequent users in 2022 far more likely to report anxiety, depression, or suicidal thoughts than non-users.
This study does not establish causation but identifies an important public health trend: increasing co-occurrence of cannabis consumption and internalizing mental health problems across the Canadian population, with particularly strong signals among young people.
Key Facts
- Rising internalizing disorders: Reported generalized anxiety disorder rose to about 5.2% and major depressive episode to about 7.6% by 2022—approximately doubling from 2012 levels.
- More frequent cannabis use: The proportion of Canadians using cannabis multiple times per week more than doubled, and 20.7% reported past-year use by 2022.
- Youth vulnerability: Suicidality increased by 44% among youth (ages 15–24) while remaining relatively stable in older adults. Younger people showed some of the strongest links between cannabis use and mental health disorders.
- Higher risk for regular users: In 2022, people who used cannabis two or more times per week were about five times more likely to report anxiety, depression, or suicidality than non-users.
- Clinical implications: Researchers recommend routine screening for cannabis use in mental health settings and earlier identification of anxiety, depression, and suicidal thoughts among people who use cannabis.
Study overview
Researchers from McMaster University analyzed two nationally representative cross-sectional surveys of Canadians aged 15 and older: the 2012 Canadian Community Health Survey – Mental Health component (CCHS-MH) and the 2022 Mental Health and Access to Care Survey (MHACS). Combined, these surveys included about 35,000 respondents and allowed comparison of cannabis use frequency alongside past-12-month generalized anxiety disorder (GAD), major depressive episode (MDE), and suicidality over the ten-year period.
Because Canada legalized recreational cannabis midway through the study window, the authors note changes in market availability, product potency, and social norms as likely contributors to observed patterns. They caution that the study shows co-occurrence rather than direct causation, but the strengthening associations are notable for public health planning.
Findings in detail
- Across the whole population the prevalence of GAD, MDE, and cannabis use roughly doubled from 2012 to 2022.
- Frequency of cannabis use showed a dose-response relationship with mental health outcomes: higher use frequency was consistently associated with higher prevalence of anxiety, depression, and suicidality.
- Additive interactions comparing 2012 to 2022 demonstrated that associations between cannabis use and these mental health outcomes became stronger over time. For example, regular users (2+ times per week) moved from roughly two- to three-fold prevalence ratios in 2012 to about five-fold prevalence ratios by 2022 for several outcomes.
- Some subgroups showed stronger moderation effects: associations between cannabis and major depressive episodes or suicidality intensified more among youth (15–24), while associations with generalized anxiety disorder strengthened more among females.
Implications for clinicians and public health
The research team recommends routine screening for cannabis use in mental health settings and greater emphasis on early detection of anxiety, depression, and suicidality among people who use cannabis. They call for improved prevention strategies, expanded access to integrated services that treat substance use and mental health together, and updates to Canada’s Lower Risk Cannabis Use Guidelines to reflect emerging evidence of stronger associations.
Lead author Jillian Halladay and colleagues emphasize the importance of recognizing bidirectional influences: people may use cannabis to self-manage anxiety or depressive symptoms, while high-potency products and patterns of frequent use may worsen mental health over time. For clinicians, assessing both cannabis use patterns and mental health symptoms together has growing importance.
Key questions answered
A: This research documents a strong co-occurrence between cannabis use and internalizing disorders but does not prove cause and effect. The relationship is likely complex and bidirectional: some people may use cannabis to relieve symptoms, while others may experience worsening symptoms after prolonged or high-potency use.
A: Since legalization, the cannabis market has expanded with higher-potency products and greater availability. Increased use for stress relief combined with these market changes may contribute to stronger associations between use and mental health outcomes over time.
A: The highest risks were seen in regular users (twice weekly or more). However, the study found that people who used cannabis at any level were more likely than non-users to meet criteria for anxiety and depression, suggesting clinicians and users should remain attentive to potential mental health effects even at lower levels of use.
Funding and acknowledgements
Funding was provided by a Health Systems Impact Embedded Early Career Researcher award co-funded by the Canadian Institutes of Health Research (CIHR), McMaster University, and St. Joseph’s Healthcare Hamilton, along with a CIHR Fellowship. Additional support came from the Australian National Health and Medical Research Council, the Peter Boris Chair in Addictions Research, and a Canada Research Chair in Translational Addiction Research.
About this research
Author: Adam Ward
Source: McMaster University
Contact: Adam Ward – McMaster University
Image credit: Neuroscience News
Original research: “Changes in Cross-Sectional Associations Between Cannabis Use and Anxiety, Depression, and Suicidality in a Nationally Representative Sample of Canadians From 2012 to 2022” by Jillian Halladay et al., Canadian Journal of Psychiatry. DOI: 10.1177/07067437261420701. Open access.
Abstract (condensed)
Objective: With evolving patterns of cannabis use and internalizing mental health problems, particularly after legalization and the COVID-19 pandemic, it is important to reassess associations between cannabis use frequency and anxiety, depression, and suicidality.
Methods: The study compared two nationally representative cross-sectional surveys of Canadians aged 15 and up (2012 CCHS-MH, n≈25,113; 2022 MHACS, n≈9,861). Robust Poisson regression examined frequency-dependent associations between cannabis use and past-year generalized anxiety disorder, major depressive episode, and suicidality.
Results: From 2012 to 2022, prevalence of GAD, MDE, and cannabis use (any and 2+/week) rose substantially, while suicidality increased among youth. Across models, greater cannabis frequency was consistently associated with higher prevalence of internalizing problems, and these associations were stronger in 2022 compared with 2012.
Conclusions: Cannabis use is associated with higher prevalence of anxiety, depression, and suicidality, and these associations strengthened between 2012 and 2022. The findings support increased investment in early identification, prevention, and integrated treatment for substance use and mental health concerns.