Does cannabis use predict the first incidence of mood and anxiety disorders in the adult population?

<h4>Aims</h4>To investigate whether cannabis use predicted the first incidence of mood and anxiety disorders in adults during a 3-year follow-up period.<h4>Design and participants</h4>Data were derived from the Netherlands Mental Health Survey and Incidence Study (NEMESIS), a prospective study in the adult population of 18-64 years. The analysis was carried out on 3881 people who had no life-time mood disorders and on 3854 people who had no life-time anxiety disorders at baseline.<h4>Measurements</h4>Life-time cannabis use and DSM-III-R mood and anxiety disorders, assessed with the Composite International Diagnostic Interview (CIDI).<h4>Findings</h4>After adjustment for strong confounders, any use of cannabis at baseline predicted a modest increase in the risk of a first major depression (odds ratio 1.62; 95% confidence interval 1.06-2.48) and a stronger increase in the risk of a first bipolar disorder (odds ratio 4.98; 95% confidence interval 1.80-13.81). The risk of 'any mood disorder' was elevated for weekly and almost daily users but not for less frequent use patterns. However, dose-response relationships were less clear for major depression and bipolar disorder separately. None of the associations between cannabis use and anxiety disorders remained significant after adjustment for confounders.<h4>Conclusions</h4>The associations between cannabis use and the first incidence of depression and bipolar disorder, which remained significant after adjustment for strong confounders, warrant research into the underlying mechanisms.