The impact of medical marijuana laws on youth attitudes toward and use of illicit substances

Since 1996, 18 states (including DC) have passed laws that decriminalize marijuana use for medicinal purposes. Another 12 states are currently deliberating. Medical marijuana (MM) laws are intended to help patients cope with chronic pain and loss of appetite accompanying serious illness. They could, however, have unintended consequences for adolescents and young adults. It has long been argued that decriminalization could inadvertently “send the wrong message” to young people about the risks of using drugs. If poorly regulated and enforced, MM laws could also increase access to illicit marijuana and drive down its price, thereby leading to increased cannabis consumption and problems among young people.  This serial cross-sectional study examines the impact of medical marijuana (MM) laws on drug-related attitudes, initiation, consumption, and substance use disorders among U.S. adolescents and young adults.

We characterize the characteristics of state MM laws along three dimensions – ease of becoming a permitted user, quantity of product permitted, and organization of distribution system. The three indices that measure these characteristics were developed using a Delphi method after review of the statutory details of all state MM laws. We link these data, along with other state-level explanatory variables, with individual-level data from the National Survey on Drug Use and Health (NSDUH). The individual-level NSDUH data have only recently become available through a secure data system; this analysis is one of the first uses of the confidential data. Explanatory variables include state-level demographic characteristics, state-level economic variables, and other state laws that pertain to marijuana and alcohol.

Our central hypothesis is that state MM laws will be associated with decreased perceptions of risk and increased cannabis use, initiation, earlier age at first use and substance use disorders (e.g., abuse, dependence). At the same time, we hypothesize that marijuana will be an economic substitute for alcohol and other illicit drugs, thereby leading to reduced consumption and harms attributable to these other substances. We test whether the presence and characteristics of MM laws affect these outcomes using Generalized Estimating Equations (GEE). We use instrumental variables and/or other methods to address the non-random passage of MM laws across states. Results are too preliminary to report at this time, but as we now have access to the individual-level data we expect to have reportable results in April.