Medical marijuana and suicide

A priori, it's hard to tell what increased marijuana access would do to suicide rates. There's evidence of comorbidity of marijuana use and psychological disorders, but sorting out causality is tough - marijuana can often be a form of self-treatment for those with existing disorders. Similarly, marijuana could attenuate or exacerbate the effects of significant life events that bring on marijuana use.

The University of Bonn's Institute for the Study of Labor (IZA) this year released a working paper (HT: @ColbyCosh) using US panel data to show that medical marijuana legislation is associated with strong decreases in suicide rates.

Our results suggest that the passage of a MML is associated with an almost 5 percent reduction in the total suicide rate.  

When we examine the relationship between legalization and suicides by gender and age, we find evidence that MMLs are associated with decreased suicides among 20-through 29-year-old males and among 30- through 39-year-old males.  This result is consistent with registry data from Arizona, Colorado, and Montana showing that most medical marijuana patients are male, and that roughly half are under the age of 40 (Anderson et al. 2011).  Estimates of the relationship between legalization and suicides among females are less precise, and are sensitive to functional form.  We conclude that the legalization of medical marijuana leads to an improvement in the psychological well-being of young adult males, an improvement that is reflected in fewer suicides.  

Shame Obama's been cracking down on the dispensaries providing product to those with medical marijuana prescriptions; a greater shame that New Zealand doesn't yet allow medical marijuana.