Cannabis, Psychosis, and Mortality: A Cohort Study of 50,373 Swedish Men.
Edison Manrique-Garcia, Antonio Ponce de Leon, Christina Dalman, Sven Andréasson, Peter Allebeck
The American journal of psychiatry August 1, 2016 DOI: 10.1176/appi.ajp.2016.14050637 (opens in new tab) via PubMed
Summary
AI-generated from the abstractHeavy cannabis use at age 18-19 is linked to a 40% higher risk of death up to around age 60, compared with nonuse. People with psychotic disorders have about a 3.7-3.8 times higher risk of death regardless of whether they used cannabis. There is no combined effect: cannabis use does not further raise mortality risk in those with psychosis. The findings come from a longitudinal study of 50,373 Swedish male conscripts followed for about 40 years. Results are cautious because the study lacked information on later-life confounders.
Study at a glance
| Characteristics | Longitudinal study Peer reviewed |
|---|---|
| Sample size | 50,373 |
| Population | Swedish male military conscripts ages 18-19 |
| Duration | Followed up to around age 60 |
| Key finding | Heavy cannabis use at baseline was associated with a 40% higher risk of death (hazard ratio=1.4); cannabis use did not interact with psychotic disorders to affect mortality. |
Abstract
The authors assessed 1) the overall risk of death among cannabis users compared with nonusers and the extent to which psychosis affects excess mortality; 2) mortality among persons with psychotic disorders and the extent to which cannabis use affects excess mortality; and 3) the interaction effect of cannabis use and diagnosis of psychotic disorders on mortality. This was a longitudinal study of 50,373 Swedish male military conscripts (ages 18-19) who were followed in the National Cause of Death Register up to around age 60. Cox proportional hazard modeling was used to assess risk of death in relation to baseline cannabis use and diagnosis of psychotic disorders. Subjects with a baseline history of heavy cannabis use had a significantly higher risk of death (hazard ratio=1.4, 95% CI=1.1, 1.8) than those without such a history. The authors found an excess mortality among subjects with psychotic disorders, but the level did not differ between those with a history of cannabis use (ever users: hazard ratio=3.8, 95% CI=2.8, 5.0; heavy users: hazard ratio=3.8, 95% CI=2.6, 6.2) and those without such a history (hazard ratio=3.7, 95% CI=3.1, 44). No interaction was observed between cannabis use and diagnosis of psychotic disorders with regard to mortality. The results suggest that individuals with an early history of heavy use of cannabis are at a higher risk of death than those with a history of no use of cannabis. Although the authors adjusted for several confounders at baseline, the results should be interpreted with caution because of a lack of information on confounders in the period after conscription.