States with Medical Marijuana See a Drop in Prescriptions for other Drugs

 A new study published in the journal Health Affairs shows a significant reduction in prescription painkiller use as well as other prescribed drugs in states where medical marijuana has been legalized. 

Researchers at the University of Georgia analyzed data on all Medicare part D prescriptions filled by enrollees from 2010 to 2013, and looked for conditions that could be alternatively treated with medical marijuana.  Medicare part D covers the costs of prescription medications for people over 65 and people with certain disabilities and other complex medical conditions.

The results show that prescriptions to treat anxiety, depression, nausea, pain, psychosis, and sleep disorders all were lower in states where medical marijuana use is legal, even after controlling for other factors that could influence prescription levels.  

Their findings suggest that medical marijuana could not only help stem abuse and addiction by lowering the amount of prescribed opioids and serving as a less adictive substitute treatment, but also lower healthcare spending since neither Medicaid nor Medicare cover the costs associated with purchasing medical cananbis. The study estimates that if all 50 states legalized medical marijuana, total Medicare spending for prescriptions could drop by almost $500 million.

Earlier studies looking into the relationship between marijuana laws and opioid abuse have produced similar findings.  A 2014 article published in the Journal of the American Medical Association found that states that had legalized medical marijuana had 24.8 percent fewer opioid overdose fatalities than states that did not.  Additionally, a 2015 study found that medical marijuana states not only experienced fewer overdose fatalities, but also a 15 to 35 percent reduction in substance abuse treatment for painkiller addiction.

Despite these findings, some researchers have cautioned against using state-level data to make inferences about individual behavior.  Keith Humphreys, a research scientist at Stanford, has argued that the only way to accurately study the influence of medical marijuana on opioid use is to study individuals directly.

One individual-level study of prescription opioid users in Australia found that those who were also prescribed medical marijuana had a higher propensity to abuse opioids and engage in other factors that increase the risk of overdose such as alcohol and benzodiazepine use. This study, however, only examined individuals who were prescribed both opioids and medical marijuana and therefore is not suggestive for determining the effects of using medical marijuana as an alternative to opioid treatments.

An overview of legalization in Ohio, the most recent state to allow medical marijuana, as well as a complete list of medical marijuana polices by state can be found here.