A newly published study from Yale University found that recreational marijuana use was associated with increased impulsivity and greater hostile perceptions and behaviors.

While the negative effects of chronic marijuana use are being documented in a growing body of research, it has been unclear whether recreational use of the substance produces problematic effects in everyday life.

A new study, published online ahead of print in the journal Drug and Alcohol Dependence, suggests that recreational users of marijuana may experience deleterious effects on impulse control and increases in hostility.

Participants in the study used smartphones to monitor their use of marijuana, alcohol, and tobacco, and to assess the impulsivity of their actions, hostile behaviors, and perceived hostility during social interactions. For each subject, days of marijuana use and non- use were compared to look for changes in impulsivity and social behaviors resulting from use.

The findings show that on days where use occurred, impulsivity and hostility were higher than days where no use occurred. Impulsivity was also higher on the day after marijuana use, suggesting a directional and lasting effect of marijuana use on impulse control.

“Contrary to perceptions of low associated risk with marijuana use among young adults, our findings suggest that recreational use of marijuana may have negative impacts on day-to-day psychological processes and psychosocial function,” said Emily Ansell, lead author and assistant professor of psychiatry at Yale School of Medicine. The results could have implications for recent changes in the legal status of marijuana in some states.

Additional co-authors include Holly Laws of Yale, Michael Roche of Pennsylvania State University, and Rajita Sinha, Foundations Fund Professor of Psychiatry and professor in the Child Study Center and of neurobiology at Yale School of Medicine.

Publication: Emily B. Ansell, et al., “Effects of marijuana use on impulsivity and hostility in daily life,” Drug & Alcohol Dependence, 2015; doi:10.1016/j.drugalcdep.2014.12.029

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