Motivation Precedes Goal Setting in Prediction of Cannabis Treatment Outcomes in Adolescents.

Studies have shown that motivation to change is related to better substance use outcomes among treatment-seeking adolescents. Goal setting, which may be related to motivation, also has been shown to be associated with positive treatment outcomes. However, relationships between motivation and goal setting as mediators of change in cannabis use over time among treated youth have not been investigated. This study tested direct and indirect associations of motivation and goal setting with cannabis use frequency over 12 month follow-up among treated adolescents. A longitudinal study of 163 adolescents enrolled in intensive outpatient substance use treatment (mean age = 16.69, 34% female, 87% Caucasian) provided repeated assessment of motivation, goal setting, and cannabis use. Path analysis tested direct and indirect effects of motivation and goal setting on cannabis use. A comparison of two path models that tested motivation and goal setting independently showed that goal setting had better model fit and accounted for more of the variance in 6-month ( R2 = .35) and 12-month ( R2 = .46) cannabis use frequency than motivation ( R2 = .28, .44, respectively). When both mediators were included in the same model, better model fit was found for motivation preceding goal setting in the context of double mediation. Overall, results suggest that goal setting, or the combination of motivation preceding goal setting in a double mediation model, predicted lower cannabis use in treated adolescents.