Stewart DG, Felleman BI, Arger CA. Effectiveness of Motivational Incentives for Adolescent Marijuana Users in a School-Based Intervention.
J Subst Abuse Treat 2015;
58:43-50. [PMID:
26231697 DOI:
10.1016/j.jsat.2015.06.002]
[Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 05/26/2015] [Accepted: 06/01/2015] [Indexed: 10/23/2022]
Abstract
PURPOSE
This study examined whether adolescents receiving Motivational Interviewing (MI) intervention have different outcomes compared to those receiving Motivational Incentives (Motivational Interviewing combined with Contingency Management; MI+CM).
METHOD
A total of 136 adolescents (from a parent study of 220 adolescents) with problematic substance use were recruited from 8 high schools in Washington State, where they completed either 8-weeks of MI or MI+CM. Frequency of marijuana use was assessed at baseline, at the end-of-treatment, and at 16-week follow-up.
RESULTS
A balanced and matched sample was created using propensity scores, then analyzed using Hierarchical Linear Modeling (HLM). Multilevel regression analyses revealed that adolescents who received MI+CM exhibited a greater reduction in use across time (p<.05). Reductions at the end-of-treatment were greater for the MI+CM condition (Cohen's d=-.82) compared to MI alone (Cohen's d=-.33), but did not differ at 16-week follow-up. Adolescents receiving MI+CM showed significantly fewer negative consequences of marijuana use at the end-of-treatment (t1, 124=2.26, p<.05), higher use of coping strategies (t1, 124=3.01, p<.01), and increased likelihood to attend additional treatment for substance use (χ2 1, 124=4.12 p<.05), though hypothesized improvements in motivation and school attendance were not found. Use of coping strategies at the end-of-treatment had a significant indirect effect on the relationship between the intervention condition and marijuana use at the end-of-treatment (F3, 121=10.20, R2=.20, p<.01).
CONCLUSION
These results suggest that the inclusion of contingencies into adolescent marijuana treatment decreases the end-of-treatment frequency of marijuana use and related consequences while increasing the use of coping strategies and the pursuit of additional treatment.
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