Augmenting Brief Interventions for Adolescent Marijuana Users: The Impact of Motivational Check-Ins

Objective: Brief interventions for adolescent marijuana users offered in schools reach users who would not otherwise present for treatment. The current study builds on previous trials of a school-based, 2-session motivational enhancement therapy (MET) intervention by adding periodic, brief motivational check-ins to reinforce gains and bolster motivation. Method: Adolescent participants were randomly assigned to a motivational check-in (MCI; n = 128) or assessment-only check-in (ACI; n = 124) comparison condition. Both conditions received 2 sessions of MET. Participants in the MCI condition then attended 3 MET-based check-in sessions at 4, 7, and 10 months after baseline, whereas the ACI condition participants attended assessment-only check-ins at the same time points. Optional cognitive behavior therapy (CBT) sessions were available as needed for 12 months from baseline in both conditions. Results: Outcomes were assessed at 6, 9, 12, and 15 months after baseline. Participants (59% Caucasian; 68% male; mean age = 15.84) reported using marijuana on an average of 37 of the last 60 days, and 70% met diagnostic criteria for a marijuana use disorder. Both conditions were associated with reduced use and negative consequences that were sustained throughout the 15 months of follow-up. The MCI condition resulted in greater reductions at the 6 months follow-up, but differences between conditions were not found at later follow-ups, and MCI participation did not increase engagement in CBT as predicted. Conclusions: Results replicated the efficacy of the brief intervention for adolescent marijuana use and provided mixed evidence on the utility of adding repeated check-in sessions. What is the public health significance of this study? Marijuana is the most widely used illicit substance in the United States, with approximately 25 million people having used marijuana at least once in the past year. An estimated 10% of persons who have ever used marijuana will become daily users, with lifetime marijuana dependence rates estimated at 4% of the general population, the highest of any illicit drug. Given that the great majority of adults with 1 or more marijuana use disorder symptoms report they began smoking before age 18, early intervention efforts with adolescents, particularly those who are using heavily, becomes an important public health objective in order to prevent later problems.