An analysis of 35,000 Canadians shows that rising cannabis use and worsening mental‑health symptoms are increasingly appearing together, with the connection between the two strengthening over time.
The study, led by McMaster University and published in The Canadian Journal of Psychiatry on Feb. 25, 2026, analyzed data from two large, nationally representative Statistics Canada surveys of Canadians aged 15 and older living in the provinces, to examine cannabis use and mental‑health outcomes between 2012 and 2022.
With the legalization of cannabis in Canada landing at the midpoint of the study period, the authors suggest that stronger products, wider availability and increased use for stress relief – may be contributing to the patterns they observed. The study doesn’t prove causation, but it underscores a widening public‑health issue as cannabis use and mental‑health challenges rise in parallel.
"We see that Canadians who use cannabis tend to be more likely to meet criteria for anxiety and depressive disorders, and more likely to report suicidality. We also see that this co-occurrence has strengthened over time,” said Jillian Halladay, an assistant professor in the School of Nursing at McMaster and youth substance use research lead at the Peter Boris Centre for Addictions Research, a joint collaboration between McMaster and St. Joseph’s Healthcare Hamilton.
Key findings:
“This extends our prior study that similarly found a strengthening in the co-occurrence of cannabis use and these mental health problems between 2002 and 2012.”
Halladay and her fellow researchers emphasize that the growing overlap between cannabis use and mental health problems highlights the need for earlier detection of anxiety, depression, and suicidality among people who use cannabis, as well as routine screening for cannabis use in mental health settings.
The team also calls for improved prevention efforts, easier access to services that treat substance use and mental health issues together, and updates to Canada’s Lower Risk Cannabis Use Guidelines to reflect these strengthening associations. The study highlights the need for earlier detection of anxiety, depression, and suicidality among people who use cannabis, as well as routine screening for cannabis use in mental‑health settings.
“It’s important for people to recognize when and how their cannabis use may be impacting their mental health, and how their mental health may be influencing their cannabis use. It’s also increasingly important for health and mental health providers to assess and address both cannabis use and mental health concerns together.”
This study furthers recent research from McMaster that found anxiety and depression rates among teenagers increased nearly three-fold over the last decade. In that study, rates of anxiety and depression were higher in teens who use cannabis heavily.
The research was funded through 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.
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For a copy of the study or to arrange interviews, contact Adam Ward, media relations officer with McMaster University's Faculty of Health Sciences, at warda17@mcmaster.ca.
The Canadian Journal of Psychiatry