The Impact of Parental Involvement in Brief Interventions for Adolescent Marijuana Use

Introduction: Marijuana use in adolescence represents a significant risk factor for multiple negative outcomes, including limited academic achievement, risky sexual behavior, delinquency, and problematic use of other substances (Brook, Balka, & Whiteman, 1999). Evidence-based brief interventions for adolescent substance use represent a promising future direction in innovating treatment in this area (Winters et al., 2012). These interventions typically involve 1 to 4 sessions and include a motivational component. The goal of this study was to investigate the role of parent involvement in a brief substance use intervention on marijuana use outcomes for adolescents who present with or without existing marijuana dependence diagnoses.

Methods: A sample of 256 adolescents (aged 12 – 18 years) and their parents participated in a randomized controlled trial of two brief intervention conditions for adolescent substance use. Adolescents were divided approximately equally by gender and approximately two-thirds were European-American. Participants were referred by school staff due to concerns about substance use. They were randomly assigned to receive either a 2-session adolescent-only intervention (Youth) or a 2-session adolescent intervention with an additional parent session (Youth + Parent). Interventions were manually guided and delivery by counselors in a school setting. Assessments of marijuana use were completed at intake and a 6 month follow-up. Both intervention formats have been previously reported to be effective in reducing marijuana use when compared to a control condition (Winters et al., 2012).

Results: Using data from the 6-month follow-up point, a latent outcome variable was created representing multiple reports of youth-reported marijuana use outcomes. Predictors included treatment condition, diagnostic status at baseline, and an interaction term between treatment condition and diagnostic status. The model fit the data well (CFI = .99; SRMR = .019) and revealed that the Youth + Parent condition produced greater reductions in marijuana use when compared to the Youth condition (B =- .15, p<.05). The interaction term also added significantly to the model (B =- .13, p<.05) and revealed that youth with marijuana dependence diagnoses at baseline had a greater benefit from the parent component than those youth without an initial diagnosis.

Conclusions: Results of this study indicate that a parent component in a brief intervention for adolescent substance improves marijuana use outcomes for all youth, but is most beneficial for those youth with higher initial severity of marijuana use. These findings have implications for tailoring brief interventions for youth based on their initial marijuana use severity in order to improve outcomes.