Annual rates of overdose deaths related to prescription painkillers are an average of 24.8% lower in states with medical marijuana programs, a new study indicates. The researchers also found that such programs are associated with significantly lower opioid overdose mortality rates, and that the lower rate of overdose mortality strengthened over time. The authors of the study note that their analysis did not account for differences in health attitudes from state to state that could contribute to the correlation, according to Smithsonian. Critics contend that the study failed to examine the influence of other prevention and treatment measures such as expanded methadone and buprenorphine programs, reports CNN. The study “Medical Cannabis Laws and Opioid Analgesic Overdose Mortality in the United States, 1999-2010,” is available on the JAMA Internal Medicine website.