All participants completed a telephone-administered adaptation of the SSAGA, a semi-structured diagnostic interview designed for genetic studies of alcoholism (36). Interviews were completed by lay interviewers who received 2-weeks of basic training in telephone-interviewing and continuing in-service training (33). Interviewers were supervised by a Master’s-level Clinical Psychologist, and interviews were audio-taped for quality-control purposes unless permission to do so was refused. The SSAGA has been shown to have excellent within-center and across-center AD reliability (kappas: 0.84–0.89, [36]) and test-retest reliability (tetrachoric correlation=0.77, [33]). Alcohol use and lifetime DSM-IV alcohol abuse and dependence questions were asked of all respondents who had either used alcohol regularly (defined as having consumed alcohol at least once a month for 6 months or more) or who reported having gotten drunk. Heaviness of consumption was assessed through 2 lifetime indices and 3 indices from the 12-month period of heaviest use. Lifetime indices were maximum drinks consumed in a 24-hour period (log-transformed) and maximum tolerance (maximum drinks consumed before becoming drunk, or maximum drinks consumed before feeling any effect for those who had never been drunk; log-transformed).
