Predicting life-time and regular cannabis use during adolescence; the roles of temperament and peer substance use: the TRAILS study.

AIMS: The aim of the present study was to determine the mediating role of affiliation with cannabis-using peers in the pathways from various dimensions of temperament to life-time cannabis use, and to determine if these associations also contributed to the development of regular cannabis use.
METHODS: Objectives were studied using data from 1300 participants of the Tracking Adolescents' Individual Lives Survey (TRAILS), a large, general population study of Dutch adolescents. We used parent-reports on the Early Adolescent Temperament Questionnaire to assess the dimensions of high-intensity pleasure, shyness, fearfulness, frustration and effortful control at age 10-12 years. By means of self-reports, life-time and regular cannabis use were determined at age 15-18 years, and proportion of substance-using peers was determined at ages 12-15 and 15-18 years. Models were adjusted for age, sex, intelligence and parental cannabis use.
RESULTS: High-intensity pleasure [odds ratio (OR) = 1.09, 95% confidence interval (CI) = 1.05-1.13] and effortful control (OR = 0.92, 95% CI = 0.89-0.96) affected the risk for life-time cannabis use through their influence on affiliation with cannabis-using peers. Shyness affected this risk independently from peer cannabis use. Only the pathway from effortful control was associated additionally with the development of regular cannabis use (OR = 0.93, 95% CI = 0.89-0.98).
CONCLUSIONS: Peer cannabis use and, to a lesser extent, certain temperamental characteristics affect an adolescent's risk of cannabis use, and should be considered in prevention programmes. We recommend future research to focus upon factors that potentially modify the association between temperament, affiliation with cannabis-using peers and cannabis use.