Citation

Schubart CD, Boks MPM, Breetvelt E, van Gastel W, Groenwold R, Ophoff R, Sommer IEC, Kahn R. Acta Psychiatr. Scand. 2011; 123(5): 368-375.

Copyright

(Copyright © 2011, John Wiley and Sons)

DOI

10.1111/j.1600-0447.2010.01640.x

PMID

unavailable

Abstract

Objective: To investigate the relationship between cannabis use and mental health.

Method: A cross‐sectional analysis in a sample of 17 698 individuals with a mean age of 22 years (SD: 4.2). Participants provided information on the amount and initial age of cannabis use and history of psychiatric hospitalizations through a web‐based questionnaire. To quantify Δ⁹‐tetrahydrocannabinol exposure, we operationalized cannabis use as the amount of money spent on cannabis per week over the last month. The odds ratio of having a history of psychiatric hospitalizations was the primary outcome measure.

Results: We found a dose-response relationship between the amount of cannabis use and the odds for psychiatric hospitalization. Adjusted odds ratios for hospitalization increased with the amount of cannabis consumed from 1.6 (95% CI: 1.1-2.3) in incidental users to 6.2 (95% CI: 4.3-8.9) in heavy users (>€25/week). Our data suggested that concomitant drug use was an intermediate factor. Exposure to cannabis before the age of 12 years was found to carry a 4.8 (95% CI: 2.9-7.8) times increased odds for past psychiatric hospitalizations.

Conclusion: We conclude that early and heavy uses of cannabis are each and independently associated with poor mental health in its users.