Data were drawn from the baseline through 10-year follow-up data collection conducted with the prospective cohort of the Collaborative Study of the Genetics of Alcoholism (COGA), which is characterized in detail elsewhere (Bucholz et al., 2016). Briefly, the parent COGA study (Begleiter et al., 1995; Reich, 1996) aimed to delineate the genetic and environmental underpinnings of alcoholism and comorbid psychiatric disorders. High risk families were identified through probands who were in inpatient or outpatient clinics for alcohol problems; families with 2 additional relatives with alcoholism were further prioritized. Control families were ascertained from a variety of sources (e.g., driver’s license records) and alcoholism was not an exclusion criterion. First degree relatives and, in some cases, members from the extended pedigree, were interviewed. The prospective component of COGA is an ongoing data collection project that aims to understand the impact of genes and environment on substance use and related milestones in youth and young adults, most of whom (86.7%) are at high familial risk for alcoholism. In 2005, adolescent and young adult offspring born from 1982 onwards were recruited from alcoholic
