Sustained alcohol, nicotine, and marijuana misuse can progress to dependence and contribute to failure to successfully adopt adult roles and to the emergence of costly social, health, and mental health problems. 7; 8 It is critically important to understand predictors and mechanisms of persistence and desistence of alcohol use and related harms during young adulthood. Further, understanding how adolescent and adult influences lead to reductions in alcohol and other drug use is important in the current context where adult roles (e.g., marriage, child rearing, and education) are being progressively delayed. This study will identify processes that influence young adult persistence or desistence in alcohol, tobacco, and marijuana misuse and problem behavior. WA and VIC were chosen for their many similarities but also their critical substance use policy differences. Increased variation in substance use due to policy differences increases power to detect relationships and mechanisms, and provides a unique and important opportunity for testing existing theories and prevention models of harmful alcohol use. Results will inform the development of effective prevention and treatment interventions aimed at reducing adult alcohol use and related harms.
The study will follow up the Washington State (WA) International Youth Development Study (IYDS) cohort at ages 29 and 31 years. The proposed study will contribute to the scientific understanding of modifiable factors that influence adult alcohol problems. The IYDS is a gender-balanced, multiethnic, sample that was designed to be representative of students in WA and VIC in 2002. The study used matched assessments and methods to enable valid cross-national comparisons of the two states. The panel of 1,556 participants was previously interviewed at ages 13, 14, 15, and 25.