Among 544 patients seeking substance use disorder treatment, those currently using cannabis had higher rates of trauma history, psychiatric diagnoses, and suicidality than lifetime or never users.
Addiction treatment providers and people in SUD treatment who also use cannabis.
Trauma may mediate the cannabis-mental health link in SUD patients
What the researchers found
Cannabis use was significantly associated with trauma history and several psychiatric diagnoses including anxiety and depression, with the highest prevalence in current users. However, cannabis use was not independently associated with anxiety, depression, sleep quality, or disability scores after controlling for trauma exposure, suggesting trauma may mediate the relationship.
Why it matters
Understanding the mental health profile of cannabis users in SUD treatment is essential for tailoring care. The finding that trauma may explain much of the cannabis-mental health link suggests that trauma-informed approaches could be more effective than focusing on cannabis use alone.
The numbers in context
N = 544. Current users: 363, past users: 109, never users: 72. Trauma and psychiatric diagnoses significantly associated with cannabis group. Anxiety, depression, sleep, and disability scores not independently associated with cannabis use after adjusting for trauma.
How the study worked
Cross-sectional online survey of 544 patients in Ontario, Canada seeking SUD treatment. Participants grouped by cannabis use: current (past-year, n=363), past (lifetime but not past-year, n=109), and never (n=72). Validated measures assessed GAD-7, PHQ-9, PSQI, WHODAS, psychiatric diagnoses, trauma, and suicidality.
What this study cannot tell us
Cross-sectional design prevents causal inference. Self-reported measures may be subject to recall bias. Ontario-specific treatment population may not generalize. Current cannabis use was not distinguished from cannabis use disorder.
How to read the evidence
Moderate-sized cross-sectional study with validated clinical measures. Cannot determine causation.
When this study was published
Published in 2025.
The bigger picture
The high overlap between cannabis use, trauma, and psychiatric comorbidity in SUD treatment populations suggests these issues need integrated rather than siloed treatment approaches.
Questions still open
- Would trauma-focused therapy reduce cannabis use in this population? Is cannabis use a consequence of, or a coping response to, trauma and mental illness?
Common questions
Does cannabis make mental health worse in people with addiction?
Should SUD treatment programs address cannabis use?
Read the original research
Associations Between Cannabis Use and Mental Health in Patients Accessing Treatment for Substance Use Disorders: An Exploratory Cross-Sectional Study.
Substance use & misuse, 60(12), 1883-1891
Citation
Matheson, Justin; MacKillop, James; Sloan, Matthew E; Sanches, Marcos; Saini, Harseerat; Haines-Saah, Rebecca; Zaweel, Adam; Hassan, Ahmed; Buckley, Leslie; Porath, Amy; Hendershot, Christian S; Kloiber, Stefan; Le Foll, Bernard. (2025). Associations Between Cannabis Use and Mental Health in Patients Accessing Treatment for Substance Use Disorders: An Exploratory Cross-Sectional Study.. Substance use & misuse, 60(12), 1883-1891. https://doi.org/10.1080/10826084.2025.2519419
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