Teens Reducing Marijuana Also Drank Less Alcohol When Taking NAC | Research

The takeaway

In a marijuana cessation trial for teens, those taking N-acetylcysteine who reduced marijuana use also reduced alcohol use, while this relationship was not seen in the placebo group.

Read this if you are a teen using both marijuana and alcohol, or if you work with adolescents who use multiple substances.

In the NAC group, less marijuana use was significantly associated with less alcohol use (p = 0.016).

What the researchers found

In a secondary analysis of a marijuana cessation trial for adolescents, researchers examined whether reducing marijuana use affected alcohol consumption. Among 116 marijuana-dependent adolescents aged 15-21, most (77 of 89 who returned for follow-up) also drank alcohol, averaging 1.3 binge drinking days per week.

A key interaction emerged: in the NAC-treated group, less marijuana use (measured by urine testing) was associated with less alcohol use. This relationship was not found in the placebo group.

Importantly, there was no evidence of compensatory drinking. The concern that teens who reduce marijuana might increase alcohol use was not supported. Instead, the opposite occurred in the NAC group: reducing one substance was associated with reducing the other.

This suggests NAC's glutamatergic mechanism may have broad effects on substance use rather than being specific to marijuana.

Why it matters

Adolescent substance use rarely involves just one substance. This finding suggests that an effective marijuana treatment may have beneficial spillover effects on alcohol use, at least when using NAC. It also addresses the common clinical concern that reducing one substance leads to increased use of another.

The numbers in context

116 adolescents randomized. 77 of 89 who returned reported alcohol use. Average 1.3 binge drinking days per week. In NAC group, less marijuana use (via urine) was significantly associated with less alcohol use (p = 0.016). No such association in placebo group.

How the study worked

Secondary analysis of an 8-week randomized, placebo-controlled trial. 116 marijuana-dependent adolescents (ages 15-21) received NAC 1200mg or placebo twice daily. Marijuana use was measured via urine cannabinoid levels. Alcohol use was assessed by self-report. Participants were not required to be alcohol users or interested in alcohol cessation.

What this study cannot tell us

Secondary analysis, not the primary study aim. Alcohol use was not the target behavior. Self-reported alcohol use may be unreliable in adolescents. The sample was moderate in size. The correlation between reduced marijuana and reduced alcohol could reflect broader lifestyle changes rather than a direct NAC effect on alcohol.

How to read the evidence

Moderate evidence from a secondary analysis of a randomized controlled trial. The association is statistically significant but was not the primary study outcome.

When this study was published

Published in 2016. NAC has continued to be studied for various substance use disorders.

The bigger picture

The finding that NAC may reduce alcohol use alongside marijuana use aligns with the glutamate hypothesis of addiction, which suggests that glutamate dysregulation is a common pathway across substance use disorders. If a single compound can address multiple substances, it would be valuable for the typical polysubstance-using adolescent.

Questions still open

Would a clinical trial specifically targeting adolescent alcohol use with NAC show significant effects? Is the NAC-marijuana-alcohol relationship causal or does reducing marijuana use naturally lead to less drinking? Would NAC be effective for adult polysubstance use?

Common questions

Does quitting marijuana make you drink more?

This study found no evidence of compensatory alcohol use when teens reduced marijuana. In fact, in the NAC treatment group, reducing marijuana was associated with also reducing alcohol use.

What is NAC?

N-acetylcysteine is an over-the-counter antioxidant supplement that affects glutamate signaling in the brain. It has shown promise for marijuana cessation in adolescents and may have broader effects on substance use behaviors.

Read the original research

Alcohol use during a trial of N-acetylcysteine for adolescent marijuana cessation.

Addictive behaviors, 63, 172-7

View on PubMed ↗Publisher’s paper ↗

Citation

Squeglia, Lindsay M; Baker, Nathaniel L; McClure, Erin A; Tomko, Rachel L; Adisetiyo, Vitria; Gray, Kevin M. (2016). Alcohol use during a trial of N-acetylcysteine for adolescent marijuana cessation.. Addictive behaviors, 63, 172-7. https://doi.org/10.1016/j.addbeh.2016.08.001