Trajectories of alcohol and cannabis use from early to late adolescence and important determinants for intervention purposes

Alcohol and cannabis use are subject to change during the adolescent period. Social, contextual and developmental factors influence the patterns of use of these substances. Longitudinal trajectory studies can shed light on the normative development of the use of these substances as well as on problematic patterns of use. It is important that underlying determinants of problematic and relatively normal use are identified so treatment efforts can be aligned towards these determinants. Results are therefore discussed with a focus on informing the development of effective intervention strategies. In this study, data of large longitudinal national representative study are presented including +/-2,230 adolescents who were followed from 11-22 years (study is ongoing). Trajectories of alcohol and cannabis use covering the whole adolescent period (14-22 years) are evaluated in relation to important cognitive determinants such as behavioral control and reward sensitivity. Latent transition analyses revealed that pubertal development as well as reward sensitivity are important predictors of the increase in both substances. Relatively stronger increase in behavioral control skills predicted decrease in the use of alcohol use, not in cannabis use, and only in a small group of adolescents (