Association between cannabis and psychiatric hospitalization


Christian Schubart, University Medical Centre Utrecht, HP. B.01.206, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.


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.