Background: Commitment to change is an innovative potential mediator and mechanism of behaviour change (MOBC) that has not been examined in adolescents with cannabis use. The Adolescent Substance Abuse Goal Commitment (ASAGC) questionnaire is a reliable and valid 2-scale measure developed to assess the adolescent’s commitment to either abstinence or harm reduction model for adolescents, which in addition to decrease in negative consequences includes consumption reduction as a stated treatment goal. The objective of this paper is to examine the ASAGC’s ability to predict adolescent substance use treatment outcome.
Methods: During Sessions 3 and 9 of a 10-week treatment program, therapists completed the ASAGC for 170 adolescents 13–18 years of age with alcohol use disorders, the majority of whom (82%) were diagnosed with co-occurring cannabis use disorder (CUD).
Results: Logistic regression analyses assessing goal commitment regarding cannabis use at Session 3 indicated that commitment to both abstinence and harm reduction predicted cannabis use at Session 3. However, only commitment to abstinence predicted later cannabis use (assessed at Session 9 and during aftercare). When goal commitment at Session 9 was examined, only commitment to abstinence predicted cannabis use, concurrently and longitudinally. These results indicated that adolescents who had higher scores for commitment to abstinence were less likely to be positive for cannabis use. In contrast, harm reduction was not a significant predictor of cannabis use.
Conclusions: Findings demonstrate that goal commitment consistently predicts cannabis use treatment outcome. Commitment to abstinence specifically is a salient predictor for concurrent and future cannabis use. A further prospective study is necessary to determine whether harm reduction may be an attainable goal for some youth given normative delayed neurodevelopmental processes of inhibitive behaviours.