New research suggests medical marijuana reforms may reduce suicide rate

The Cato Institute has posted this short research brief in which a group of social scientists summarize this study recently published in the American Journal of Public Health titled "Medical Marijuana Laws and Suicides by Gender and Age." Here are excerpts from the research brief (with references removed and my emphasis added):

Our research examines the relationship between medical marijuana laws (hereafter MMLs) and suicides. While the majority of people who suffer from mental illness do not commit suicide, over 90 percent of those who do commit suicide have a diagnosable mental or substanceuse disorder. The relationship between marijuana use and suicide-related outcomes (e.g., depression, suicidal ideation, and suicide attempts) has been studied extensively, but there have been no previous attempts to estimate the relationship between medical marijuana laws and completed suicides, the tenth leading cause of death in the United States....

Our empirical analysis draws on data from the Centers for Disease Control from 1990 through 2007 to examine the relationship between legalizing medical marijuana and suicide rates. This empirical approach can be thought of as exploiting a “natural experiment” unrelated to comorbidities or personality. 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....

We conclude that the legalization of medical marijuana leads to fewer suicides among young adult males.  This result is consistent with the oft-voiced, but controversial, claim that marijuana can be used to cope with depression and anxiety caused by stressful life events.  However, the result may, at least in part, be attributable to the reduction in alcohol consumption among young adults that appears to accompany the legalization of medical marijuana.

Our study is relevant to the ongoing debate surrounding marijuana legalization for medical or recreational purposes.  Opponents of these policy changes contend that any increase in marijuana use is undesirable.  Yet our research suggests the public-health benefits of legalization may outweigh the costs.