Data for this study were drawn from COGA, a multi-site, large, multigenerational family study that aims to understand genetic influences on alcoholism (Begleiter et al., 1995). Probands were identified through alcohol treatment programs at six U.S. sites and were invited to participate if they had a sufficiently large family with two or more members in the COGA catchment areas. Population-based comparison families were also recruited. Data collection for COGA started in 1991 (Phase I) when adults in the target extended families were invited to complete the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA), a comprehensive interview that assesses demographic factors, alcohol use behaviors, and a variety of psychiatric phenotypes (Bucholz et al., 1994). COGA Phase II data collection occurred around 1996, where participants in COGA Phase I were invited for a follow-up assessment and eligible family members who did not participate in Phase I were invited to participate as well. Participants also completed questionnaires at each phase. All COGA participants were asked to provide a DNA sample via blood or saliva. Institutional Review Boards at all sites approved this study, and written consents were obtained from participants.
