• hospitalization;
  • cannabis;
  • mental health

Schubart CD, Boks MPM, Breetvelt EJ, van Gastel WA, Groenwold RHH, Ophoff RA, Sommer IEC, Kahn RS. Association between cannabis and psychiatric hospitalization.

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.