Cannabis Use Was Linked to Suicidal Behavior Even After Accounting for Depression, Though Depression Partly Explains the Connection | Research

The takeaway

A meta-analysis of 25 studies found cannabis use was significantly associated with suicidal ideation and suicide attempts even in studies that adjusted for depression, though depression accounted for part of the relationship.

Mental health clinicians, cannabis users with depression, and researchers studying substance use and suicide risk.

Adolescent cannabis users had 2.17x the odds of suicide attempts even after adjusting for depression

What the researchers found

Among adolescents, cannabis use was associated with suicidal ideation (OR=1.46) and suicide attempts (OR=2.17) in studies adjusting for depression. Among adults, cannabis was associated with suicidal ideation (OR=1.78) after depression adjustment. However, 12 of 25 studies found no association after adjusting for depression. Studies examining depression as a moderator produced conflicting results.

Why it matters

The cannabis-suicide link has been debated, with critics arguing depression explains it entirely. This meta-analysis shows the association persists even after accounting for depression in many studies, while also acknowledging that depression does partly confound the relationship.

The numbers in context

1,081 screened, 25 included. Adolescent cannabis-SI: OR=1.46 (1.17-1.83). Adolescent cannabis-attempts: OR=2.17 (1.56-3.03). Adult cannabis-SI: OR=1.78 (1.28-2.46). 12/25 studies found no association after depression adjustment. 6 studies examined moderation with conflicting results.

How the study worked

Systematic review and meta-analysis searching PubMed, Science Direct, and PsycArticles through May 2024. Included 25 quantitative observational studies investigating depression's role in the cannabis-suicidality relationship. Meta-analyses pooled adjusted odds ratios.

What this study cannot tell us

Observational studies cannot prove causation. Different studies adjusted for different confounders. Suicidal ideation and attempts were measured differently across studies. No studies investigated depression as a formal mediator. Heterogeneity in cannabis use definitions.

How to read the evidence

Strong: systematic meta-analysis with 25 studies, specific examination of depression as confounder/moderator, and consistent associations across age groups.

When this study was published

2025 study analyzing literature through May 2024.

The bigger picture

This nuanced analysis shows the cannabis-suicidality relationship is real but complex. Depression is both a confounding factor and potentially a mediating mechanism. The inconsistency across studies suggests the relationship may depend on factors like age, cannabis use patterns, and type of suicidal behavior.

Questions still open

Does cannabis increase suicide risk directly or primarily through worsening depression? Would treating depression in cannabis users reduce suicide risk? Is there a dose-response relationship between cannabis use and suicidality?

Common questions

Does cannabis cause suicidal thoughts?

This meta-analysis found a significant association between cannabis use and suicidal thoughts/attempts, even after accounting for depression. However, observational data cannot prove causation, and the relationship is complex with depression playing a partial confounding role.

Is the risk higher for teens?

Adolescent cannabis users had 2.17 times the odds of suicide attempts and 1.46 times the odds of suicidal ideation, compared to 1.78 times for adult suicidal ideation, suggesting teens may be at higher relative risk.

Read the original research

The role of depression in the relationship between cannabis use and suicidal behaviours: A systematic review and meta-analysis.

Drug and alcohol dependence, 273, 112714

View on PubMed ↗Publisher’s paper ↗

Citation

Maffre Maviel, Gustave; Somma, Camilla; Davisse-Paturet, Camille; Airagnes, Guillaume; Melchior, Maria. (2025). The role of depression in the relationship between cannabis use and suicidal behaviours: A systematic review and meta-analysis.. Drug and alcohol dependence, 273, 112714. https://doi.org/10.1016/j.drugalcdep.2025.112714