Direct and interactive effects of parent, friend and schoolmate drinking on alcohol use trajectories

Objective: This study considered the unique and interactive roles of social norms from parents, friends and schools in predicting developmental trajectories of adolescent drinking and intoxication. Design and outcome measures: Using data from the National Longitudinal Study of Adolescent Health, which followed adolescents (N=18,921) for 13 years, we used discrete mixture modelling to identify unique developmental trajectories of drinking and of intoxication. Next, multilevel multinomial regression models examined the role of alcohol-related social norms from parents, friends and schoolmates in the prediction of youths' trajectory group membership. Results: Results demonstrated that social norms from parents, friends and schoolmates that were favourable towards alcohol use uniquely predicted drinking and intoxication trajectory group membership. Interactions between social norms revealed that schoolmate drinking played an important moderating role, frequently augmenting social norms from parents and friends. The current findings suggest that social norms from multiple sources (parents, friends and schools) work both independently and interactively to predict longitudinal trajectories of adolescent alcohol use. Conclusions: Results highlight the need to identify and understand social messages from multiple developmental contexts in efforts to reduce adolescent alcohol consumption and alcohol-related risk-taking.