Alcohol use is common among college students who use marijuana. A recent study investigated whether marijuana use reduces the effectiveness of alcohol interventions delivered within a stepped-care approach, as well as the impact of such interventions upon marijuana use. Participants were 530 mandated U.S. undergraduate students. All students received a didactic Brief Advice (BA) session facilitated by a peer counselor and completed an online follow-up assessment six weeks later. Students who screened as higher-risk on this assessment were randomly assigned to receive either a Brief Motivational Intervention (BMI) (n = 211) or assessment only (n = 194). All students completed follow-up assessments at three, six, and nine months. Self-reported past-month marijuana use, heavy drinking episodes, estimated peak blood alcohol content (BAC), and alcohol-related consequences were collected at all time-points. 44.2% (n = 234) of the sample reported using marijuana at baseline. The authors analyzed the impact of each type of intervention upon alcohol and marijuana use among marijuana users and non-marijuana users. Marijuana use at baseline was not associated with changes in the frequency of heavy drinking episodes, estimated peak BAC, or alcohol-related consequences after the BA intervention. Marijuana users were more likely to have engaged in heavy episodic drinking at greater frequencies than non-users; however, marijuana use was not associated with any changes in the frequency of heavy drinking episodes during any follow-up period. Following the BMI, there were no significant interactions between marijuana user status and the frequency of heavy drinking episodes. Additionally, receiving a BMI was not associated with changes in marijuana use frequency during any follow-up period.
Take away: Among high-risk drinkers, there was no evidence receiving a Brief Motivational Intervention (BMI) was more or less effective for marijuana users than non-users, nor was receiving the BMI associated with any changes in marijuana use. Marijuana-focused interventions may be needed to change college student marijuana use.