Researchers from Emory’s Rollins School of Public Health found an increase in adult marijuana use and binge drinking after the implementation of medical marijuana laws (MML) in ten states that permit marijuana use for medical purposes.

The study findings suggest that state MML implementation between 2004 and 2012 led to a 14 percent increase in past-month marijuana use and an 18 percent increase in marijuana abuse/dependence among adults aged 21 or above. MML implementation was also associated with a 10 percent increase in binge drinking among adults of legal drinking age.

"Even if we assume that the increases in marijuana use come from those who use the drug for legitimate medical purposes, our results indicate that MML implementation could result in increases in marijuana abuse/dependence and binge drinking," explains Hefei Wen, PhD candidate, of the Department of Health Policy and Management at Emory’s Rollins School of Public Health, "These potential public health consequences may impose considerable economic and social costs on the society."

Findings did not suggest any discernible effects of MMLs on either underage drinking among those aged 12-20 nor other substance use (i.e., non-medical use of prescription pain medication, heroin use, and cocaine use) in both age groups.

Complete findings are available in the Journal of Health Economics online at: http://www.sciencedirect.com/science/article/pii/S0167629615000351

"States contemplating MMLs and other similar liberalization policies should consider a proactive approach to mitigate the undesirable effects of marijuana liberalization," says Wen.