Participants came from the Collaborative Study on the Genetics of Alcoholism (COGA) prospective study.26 COGA is a diverse family-based study the objective of which is to identify genetic and environmental factors implicated in the development of AUD and related psychiatric disorders. Probands were identified through alcohol treatment centers across 6 sites in the United States, with a seventh site added for one wave. Probands along with their families were invited to participate if the family was sufficiently large (usually sibships greater than 3 with parents available), with 2 or more members living in the COGA site’s catchment area. Comparison families not selected for the presence or absence of alcohol problems were recruited from the same communities. Beginning in 2004, a sample of adolescent and young adult offspring (12-22 years of age) of prior adult COGA participants from the initial 6 sites were recruited into the COGA prospective study on the development of alcohol use disorders and related problems.26 Participants were interviewed at enrollment and followed up at approximately biennial intervals. The Institutional Review Board at all data collection sites approved the study, and written consent (and assent for adolescents whose parents had provided consent) was obtained from all participants.
