The study, brought to you by the Institute for the Study of Labor (IZA) in Bonn, Germany, the same firm that found that legalizing medical marijuana was associated with fewer deaths on the highways — possibly because people use marijuana instead of drinking — is titled “High on Life? Medical Marijuana Laws and Suicide,” reports Christopher Shea at the Wall Street Journal.
“Using state-level data for the period 1990 through 2007, we estimate the effect of legalizing medical marijuana on suicide rates,” says the IZA Discussion Paper from January 2012. “Our results suggest that the passage of a medical marijuana law is associated with an almost 5 percent reduction in the total suicide rate, an 11 percent reduction in the suicide rate of 20- through 29-year-old males, and a 9 percent reduction in the suicide rate of 30- through 39-year-old males.”
“Estimates of the relationship between legalization and female suicides are less precise and are sensitive to functional form,” according to the study’s authors, D. Mark Anderson, Daniel I. Rees, and Joseph J. Sabia.
”Could marijuana use help individuals cope with the negative shocks to happiness that, according to Hamermesh and Soss (1974), lead to suicide?” the study’s authors ask. “Alternatively, could marijuana use magnify the impact of SLEs [stressful life events]?”
While the majority of epidemiological studies have found that cannabis use is positively associated with both the symptoms of depression and suicidal ideation, according to the study, “any association between marijuana use and outcomes such as these could be driven by difficult-to-observe factors … or simply reflect self-medication.”
A recent review of the literature, according to the study, noted that “the majority of studies for affective outcomes [such as depression and suicidal ideation] did not adequately address the problem of reverse causation as a possible alternative explanation for any association observed.”
In other words, rather than causing suicide to become more likely, it appears that existing studies haven’t sufficiently examined the possibility that any association between cannabis and suicide is due to suicidally depressed people self-medicating with marijuana.
“The current study avoids the problems of reverse causality and unobserved heterogeneity at the individual level by examining the relationship between the legalization of medical marijuana and completed suicides,” the study’s authors note.
It may be that the reduction in alcohol use after medical marijuana legalization — which was noted in IZA’s previous study — could also be a major factor in suicide reduction in states which allow medicinal cannabis. There is a strong association between alcohol consumption and suicide-related outcomes, as found by previous researchers.
According to the study’s authors, this “raises the possibility that medical marijuana laws reduce the risk of suicide by decreasing alcohol consumption.”
“Although 16 states have passed medical marijuana laws, and others are considering legalization, very little is known about the effects of these laws,” the study’s authors conclude. “Policymakers weighing the pros and cons of legalization should consider the possibility that medical marijuana laws may lead to fewer suicides among young adult males. However, the exact mechanism through which suicides are reduced remains a topic for future study.”
To read the entire study in PDF format, click here.