This project used three longitudinal cohort studies for developmentally-informed gene discovery: The Collaborative Study on the Genetics of Alcoholism (COGA), The Avon Longitudinal Study of Parents and Children (ALSPAC), and The National Longitudinal Study of Adolescent to Adult Health (Add Health). In order to model developmentally-salient genetic effects, data were aggregated within developmental periods by taking the maximum value of available data for each participant within the following age ranges: ages 12-17 (adolescence), ages 18-25 (early adulthood), and ages 26+ (adulthood). In alignment with previous work suggesting that genetic liabilities for initiation and use of alcohol are distinct (Heath et al. 1991a; Pagan et al. 2006; Fowler et al. 2007), all analyses excluded lifetime non-drinkers. Additionally, all analyses were limited to European ancestry participants to limit the confounding influence of population stratification.
