UCSF

Objective

Concurrent use of marijuana and alcohol among college students is highly prevalent and associated with negative consequences. It remains unclear whether marijuana use is influenced by or lessens the efficacy of alcohol interventions delivered within a stepped-care approach.

Method

Participants were 530 college students who violated campus alcohol policy and were mandated to an alcohol-focused brief advice (BA) session. Participants who reported continued risky alcohol use (4+ heavy drinking episodes and/or 5+ alcohol-related consequences in the past month) six weeks following the BA session were randomized to a brief motivational intervention (BMI; n=211) or assessment only (AO; n=194) condition. Follow-up assessments were conducted 3, 6, and 9months' post-intervention.

Results

Multiple regression analyses revealed that marijuana user status did not influence drinking outcomes following the BA session. However, hierarchical linear models suggested that marijuana users who were randomized to BMI or AO reported higher levels of binge drinking, pBAC and consequences compared to non-users, regardless of condition. Despite this, heavy drinking marijuana users and nonusers had equivalent reductions on alcohol use outcomes following the BMI sessions. Marijuana users who received a BMI did not significantly reduce marijuana use frequency compared to participants in the AO group.

Conclusion

Use of marijuana did not lessen the efficacy of the BA session on alcohol use or consequences. Findings suggest that marijuana users respond similarly to alcohol interventions as do non-users and can benefit from brief or more intensive alcohol interventions. A marijuana-focused intervention may be warranted to facilitate changes in marijuana use.