Couples who use marijuana are less likely to engage in domestic violence

Marital marijuana?

A new study by researchers at the University of Buffalo finds a significantly lower incidence of domestic violence among married couples who smoke pot. "Couples in which both spouses used marijuana frequently reported the least frequent IPV [intimate partner violence] perpetration," the study concludes.

These findings were robust even after controlling for things like demographic variables, behavioral problems, and alcohol use. The authors studied data from 634 couples over nine years of marriage, starting in 1996. Couples were administered regular questionnaires on a variety of issues, including recent drug and alcohol use and instances of physical aggression toward their spouses.

Previous research on the relationship between marijuana use and domestic violence has largely been based on cross-sectional data (that is, data from one point in time), and those findings have been mixed: some studies found links between marijuana use and/or abuse and domestic violence, while others did not. The Buffalo study is one of the few to use data collected over the course of decades to examine the question, putting it on solid methodological ground compared to previous work.

The authors caution that while these findings are predictive--meaning couples who smoke are less likely to commit domestic violence--they don't necessarily draw a causal line between the two behaviors. Among the connections they hypothesize, "marijuana may increase positive affect, which in turn could reduce the likelihood of conflict and aggression." Translation: stoned people are happy, and happy people don't fight.