Motives matter: predictive value of cannabis use motives in adolescents with dual disorders - A longitudinal study.

Cannabis is the most widely used illicit substance among adolescents, and early or frequent use is associated with adverse outcomes, particularly among those with dual disorders. This study examined whether specific cannabis use motives are associated with baseline clinical severity and short- and mid-term outcomes in adolescents with cannabis use disorder (CUD) and psychiatric comorbidity A sample of 235 adolescents (aged 13-18 years; 40% female), who had met DSM-5 criteria for CUD at admission to outpatient program, was recruited from a specialized hospital-based outpatient unit within the public mental health system for adolescents with dual disorders and assessed at baseline shortly after being admitted into the program, and followed up at 3 and 6 months. Cannabis use motives were measured using the Marijuana Motives Measure. Outcomes included overall clinician-rated severity and improvement (CGI-S, CGI-I), global functioning (CGAS), and biological indicators of cannabis use based on urinary Δ9-tetrahydrocannabinol (THC) concentrations. Multivariate regression models examined the predictive value of motives while adjusting for relevant variables. Coping motives were associated with greater baseline cannabis use disorder severity and lower likelihood of externalizing comorbidity. Enhancement motives were linked to lower overall clinical severity and fewer comorbid disorders, and predicted abstinence based on THC concentrations at 6 months. Conformity motives predicted abstinence based on THC concentrations at 3 months; however, no associations were observed between social or expansion motives and clinical outcomes. Overall, associations were few and generally modest in magnitude, with substantial uncertainty across estimates. These findings indicate that some cannabis use motives show selective and time-dependent associations with clinical outcomes in adolescents with dual disorders. Larger clinical samples may help clarify whether motives may aid clinical characterization and risk stratification in adolescent substance use treatment.