Twins completed adaptations of the Semi-Structured Assessment of the Genetics of Alcoholism (SSAGA; Bucholz, Cadoret, Cloninger, Dinwiddie, Hesselbrock, et al., 1994; Hesselbrock, Easton, Bucholz, Schuckit, & Hesselbrock, 1999), which was developed for the Collaborative Study on the Genetics of Alcoholism (COGA) to assess physical, psychological, and social manifestations of alcoholism and related psychiatric disorders in adults. All interviews, both initial and follow-up, were administered by trained interviewers, who were supervised by a project coordinator and clinical psychologist. Interviews were tape-recorded, with a random sampling of tapes reviewed for quality control and coding inconsistencies. Informed consent was obtained from all participants using procedures approved by the institutional review boards at both Washington University School of Medicine and Queensland Institute of Medical Research.
