Do Medical Marijuana Laws Lead to Illicit Drug Use, Cannabis Use Disorder?

Laws enacted to loosen regulations around the use and sale of marijuana for medical purposes have been implemented to benefit populations with certain chronic diseases. A new study published by JAMA Psychiatry, however, questions whether the legislation has promoted illicit cannabis use and cannabis use disorder.

The authors discovered that states with medical marijuana laws had higher rates of illicit use of the drug and cannabis use disorder. This calls into question whether the risks of the legislation outweigh the benefits it brings to patients with specific diseases.

This study is among the first to examine the differences in illicit cannabis use and cannabis use disorder before and after medical marijuana laws were passed, as well as examining individual states.

Included in the study were data from 118,497 adults included in: the 1991 to 1992 National Longitudinal Alcohol Epidemiologic Survey, the 2001 to 2002 National Epidemiologic Survey on Alcohol and Relatied Conditions, and the 2012 to 2013 National Epidemiologic Survey on Alcohol and Related Conditions-III.

The authors discovered that between 1991 to 1992 and 2012 to 2013, illicit cannabis use and cannabis use disorder increased significantly among states with medical marijuana laws compared with states that have not passed laws permitting cannabis use for medical purposes.

From 2001 to 2002 and 2012 to 2013, marijuana use increased 3.5% in states with no medical marijuana laws, while it increased 7% in Colorado, according to the study. The authors found similar patterns for cannabis use disorder.

"Medical marijuana laws may benefit some with medical problems. However, changing state laws -- medical or recreational -- may also have adverse public health consequences, including cannabis use disorders," said study author Deborah Hasin, PhD. "A prudent interpretation of our results is that professionals and the public should be educated on risks of cannabis use and benefits of treatment, and prevention/intervention services for cannabis disorders should be provided."

The authors noted little change in marijuana use disorder and a decrease in illicit marijuana use between 1991 to 1992 and 2001 to 2002, but the prevalence of use and the disorder increased between 2001 to 2002 and 2012 to 2013, according to the study.

In California specifically, the authors predicted higher rates of marijuana use and cannabis use disorder compared with other states from 1991 to 1992. During this time, the rate of illicit cannabis use was 7.6% compared with 4.5% in other states, while cannabis use disorder was 2% versus 1.15% in other states, according to the study.

However, the authors discovered that the predicted prevalence of past year use in California was not significantly different than states that passed the laws more recently, according to the study.

"Future studies are needed to investigate mechanisms by which increased cannabis use is associated with medical marijuana laws, including increased perceived safety, availability, and generally permissive attitudes," Dr Hasin concluded.