A look at 634 couples found that the more often they smoked marijuana, the less likely they were to engage in domestic violence.

The scholars attempted to clarify inconsistent findings about domestic violence among pot-smoking couples that primarily has been based on cross-sectional data (i.e., data from one point in time). Looking at couples over the first nine years of marriage, the study found:

More frequent marijuana use by husbands and wives (two-to-three times per month or more often) predicted less frequent intimate partner violence (IPV) perpetration by husbands.

Husbands' marijuana use also predicted less frequent IPV perpetration by wives.

Couples in which both spouses used marijuana frequently reported the least frequent IPV perpetration.

The relationship between marijuana use and reduced partner violence was most evident among women who did not have histories of prior antisocial behavior.

The analysis was published in Psychology of Addictive Behaviors. It was based on data collected by lead investigator Kenneth Leonard, PhD, director of the

University at Buffalo

Research Institute on Addictions.

"These findings suggest that marijuana use is predictive of lower levels of aggression towards one's partner in the following year." Leonard says. "As in other survey studies of marijuana and partner violence, our study examines patterns of marijuana use and the occurrence of violence within a year period. It does not examine whether using marijuana on a given day reduces the likelihood of violence at that time.

"It is possible, for example, that — similar to a drinking partnership — couples who use marijuana together may share similar values and social circles, and it is this similarity that is responsible for reducing the likelihood of conflict.

"Although this study supports the perspective that marijuana does not increase, and may decrease, aggressive conflict," he says, "we would like to see research replicating these findings, and research examining day-to-day marijuana and alcohol use and the likelihood to IPV on the same day before drawing stronger conclusions."