A randomized trial of contingency management for adolescent marijuana abuse and dependence

Abstract

An initial efficacy test of an innovative behavioral outpatient treatment model for adolescents with problematic use of marijuana enrolled 69 adolescents, aged 14-18, and randomly assigned them to one of two treatment conditions. Both conditions received individualized Motivational Enhancement and Cognitive Behavioral Therapy (MET/CBT) and a twice-weekly drug-testing program. The experimental contingency management condition involved a clinic-delivered, abstinence-based incentive program, and weekly behavioral parent training sessions that included a parent-delivered, abstinence-based, substance monitoring contract. The comparison condition included an attendance-based incentive program, and weekly psychoeducational parent sessions. Follow-up assessments were performed at 3, 6, and 9 months post-treatment. The experimental condition showed greater marijuana abstinence during treatment, e.g., 7.6 vs. 5.1 continuous weeks and 50% vs. 18% achieved > or = 10 weeks of abstinence. Improvements were found in parenting and youth psychopathology across treatment conditions, and improvements in negative parenting uniquely predicted post-treatment abstinence. The outcomes observed in the experimental condition are consistent with adult substance-dependence treatment literature, and suggest that integrating CM abstinence-based approaches with other empirically based outpatient interventions provides an alternative and efficacious treatment model for adolescent substance abuse/dependence. Replication and continued development of more potent interventions remain needed to further advance the development of effective substance abuse treatments for adolescents.

Figure 1

CONSORT participant flow diagram. EXP=Experimental condition; Control=Control condition

Figure 2

GEE model of marijuana positive urine drug tests from intake to 9 months post treatment. Circles and squares represent observed percentages for the CONTROL and EXP conditions, respectively. The estimated cubic curves for each treatment condition are displayed. EXP=Experimental condition; CONTROL=Control condition; UA=Urinalysis

Figure 3

Mixed model of reported percentage of days used marijuana in the 90 days prior to intake and between each subsequent assessment. Circles and squares represent observed percentages for the CONTROL and EXP conditions, respectively. The estimated cubic curves for each treatment condition are displayed. EXP=Experimental condition; CONTROL=Control condition.

Figure 4

Structural model predicting a post treatment marijuana use construct, defined by marijuana (THC) positive urine drug test results at 3, 6, and 9 month follow ups. Factor loadings of the THC result variables were all constrained to 1. EXP=Experimental condition; EXT=mean maternal and paternal CBCL Externalizing scores; Neg Dis=mean maternal and paternal APQ Negative Discipline scores; model p=.65, TLI=1.01, RMSEA=.00; Standardized coefficients are displayed; solid lines indicate estimates significant at p<.05.