In Teens and Young Adults, Does Abstaining from Cannabis Mean Drinking More Alcohol?

As more states have legalized the medical and/or recreational use of marijuana, we are seeing increased usage among teens and young adults, coupled with a steady increase in the availability of cannabis-containing products and an overall increase in the potency of these products. The use of cannabis has increased significantly over the last few decades, most notably in young adults, with 18.4% of adolescents and 32.6% of college age students in North America reporting the use of cannabis during the past 30 days. 

We are particularly concerned about the growing use of cannabis, and the associated perception that it is a recreational drug with little risk of harm, among young adults.  In terms of neurodevelopment, late adolescence and early adulthood constitute a particularly vulnerable time, as the brain is undergoing extensive changes, including the development of higher cognitive functioning and increases in connectivity between various regions of the brain.  We thus recommend that teens and young adults abstain from using cannabis. 

A new study from Randi Schuster, PhD and colleagues at the Center for Addiction Medicine at MGH raises new concerns, indicating that abstinence from cannabis in adolescents and young adults may lead to increased use of alcohol in this population.

In this study, 160 healthy, non-treatment seeking, cannabis users between the ages of 14 and 25 years were recruited.  The participants were randomly assigned to 4 weeks of cannabis abstinence using a contingency management framework (i.e., they received incentive payments for cannabis abstinence) or monitoring with no abstinence requirement.  Participants were assessed at baseline and at 4, 6, 10, 17, 24, and 31 days after enrollment.  Urine tests were used to verify cannabis abstinence.  

In this study, four weeks of incentivized cannabis abstinence among adolescents and young adults was associated with an overall increase in both the frequency and amount of alcohol used during the first week, an increase which was sustained until the resumption of cannabis use.  However, there was considerable variability in alcohol use patterns when the researchers looked at individual participants.  While 60% increased their alcohol use, 23% actually decreased their alcohol use during cannabis abstinence. 

While the finding of increased alcohol use is obviously concerning, the authors point out that the risks associated with long-term cannabis use may outweigh the risks of a small increase in alcohol use.  It is noteworthy that the youth included in the study were not seeking treatment, and it is possible that the results could be different in youth who were motivated to seek treatment.  In addition, future studies will determine whether additional recovery-related resources and support may help to reduce use of alternate substances in adolescents and young adults who are attempting to abstain from cannabis.  

Schuster RM, Potter K, Lamberth E, Rychik N, Hareli M, Allen S, Broos HC, Mustoe A, Gilman JM, Pachas G, Evins AE.  Alcohol substitution during one month of cannabis abstinence among non-treatment seeking youth.  Prog Neuropsychopharmacol Biol Psychiatry. 2021 Apr 20;107:110205.

Randi Melissa Schuster, PhD is a neuropsychologist and Director of Neuropsychology in the Center for Addiction Medicine.  She is an Assistant Professor of Psychiatry at Harvard Medical School.  Her research focuses on the cognitive ramifications of early drug exposure. She is currently funded by a five-year NIH NIDA career development award, mentored by Dr. Eden Evins in the Center for Addiction Medicine and Dr. Jordan Smoller in the Psychiatric and Neurodevelopmental Genetics Unit.