Cannabis and suicide: longitudinal study

Br J Psychiatry. 2009 Dec;195(6):492-7. doi: 10.1192/bjp.bp.109.065227.


Background: Some studies suggest that cannabis use is associated with suicidal ideation, but no detailed longitudinal study has examined suicide as an outcome.

Aims: To examine the association between cannabis use and completed suicide.

Method: A longitudinal study investigated 50 087 men conscripted for Swedish military service, with cannabis use measured non-anonymously at conscription. Suicides during 33 years of follow-up were identified by linkage with the National Cause of Death Register.

Results: There were 600 (1.2% of cohort) suicides or deaths from undetermined causes. Cannabis use was associated with an increased risk of suicide (crude OR for 'ever use' 1.62, 95% CI 1.28-2.07), but this association was eliminated after adjustment for confounding (adjusted OR = 0.88, 95% CI 0.65-1.20).

Conclusions: Although there was a strong association between cannabis use and suicide, this was explained by markers of psychological and behavioural problems. These results suggest that cannabis use is unlikely to have a strong effect on risk of completed suicide, either directly or as a consequence of mental health problems secondary to its use.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Humans
  • Longitudinal Studies
  • Male
  • Marijuana Abuse / mortality
  • Marijuana Abuse / psychology*
  • Military Personnel*
  • Odds Ratio
  • Risk Factors
  • Suicide / psychology*
  • Suicide / statistics & numerical data
  • Sweden / epidemiology
  • Young Adult