Cannabis Users in Brazil Had Three Times the Rate of Suicidal Thoughts as the General Population | Research

The takeaway

In a nationally representative Brazilian survey, cannabis users had markedly elevated rates of suicidal ideation (31.5%) and suicide attempts (16.5%) that remained significant even after controlling for demographics, tobacco use, family history, and depression.

Mental health clinicians, suicide prevention researchers, substance use counselors.

31.5% of cannabis users reported suicidal ideation vs 9.9% of the general sample; the association persisted after controlling for depression.

What the researchers found

Among cannabis users, 31.5% reported suicidal ideation and 16.5% reported suicide attempts, compared to 9.9% and 5.4% in the general sample. After adjusting for demographic characteristics, tobacco use, family history of suicide, and depression, cannabis use remained positively associated with both suicidal ideation and attempts.

Why it matters

The persistence of the cannabis-suicide association after adjusting for depression and other confounders suggests cannabis use may be an independent risk marker for suicidal behavior, warranting screening in cannabis-using populations.

The numbers in context

4,607 participants. Cannabis users: 31.5% suicidal ideation (vs 9.9% overall), 16.5% suicide attempts (vs 5.4% overall). Associations remained significant after adjusting for depression, tobacco use, family history, and demographics.

How the study worked

National probability sample survey (II BNADS) of 4,607 Brazilians aged 14+ using multistage cluster design. Self-reported substance use, suicidal ideation, and suicide attempts. Response rate 77%.

What this study cannot tell us

Cross-sectional design cannot determine causation. Self-reported measures of both substance use and suicidality. Cannabis users may differ from non-users in unmeasured ways. Brazilian context may differ from other countries.

How to read the evidence

Moderate - large nationally representative sample with 77% response rate and multivariable adjustment, but cross-sectional.

When this study was published

Published in 2019.

The bigger picture

This study from Brazil adds to a growing body of evidence linking cannabis use with suicidal behavior across diverse populations and cultures. The finding that the association persists after controlling for depression is particularly noteworthy.

Questions still open

Does cannabis use contribute to suicidal behavior or do shared risk factors explain the association? Would cannabis cessation reduce suicide risk? Should suicide screening be standard in cannabis use disorder treatment?

Common questions

Is cannabis use linked to suicide?

This Brazilian national survey found cannabis users had markedly higher rates of suicidal ideation (31.5% vs 9.9%) and suicide attempts (16.5% vs 5.4%). The association remained significant even after accounting for depression, tobacco use, and family history of suicide.

Does depression explain the link between cannabis and suicide?

Not entirely. While depression was also associated with suicidal behavior, the cannabis-suicide association persisted after controlling for depression, demographics, tobacco use, and family history. This suggests cannabis use may be an independent risk marker.

Read the original research

Suicidal behavior among substance users: data from the Second Brazilian National Alcohol and Drug Survey (II BNADS).

Revista brasileira de psiquiatria (Sao Paulo, Brazil : 1999), 41(5), 437-440

View on PubMed ↗Publisher’s paper ↗

Citation

Abdalla, Renata R; Miguel, André C; Brietzke, Elisa; Caetano, Raul; Laranjeira, Ronaldo; Madruga, Clarice S. (2019). Suicidal behavior among substance users: data from the Second Brazilian National Alcohol and Drug Survey (II BNADS).. Revista brasileira de psiquiatria (Sao Paulo, Brazil : 1999), 41(5), 437-440. https://doi.org/10.1590/1516-4446-2018-0054