All participants first provided verbal consent. A computer-assisted telephone interview adapted from the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) (Bucholz et al. 1994) was then administered. Data collected included demographic information, DSM-IV diagnoses of psychiatric and substance dependence disorders, and other non-diagnostic sections. To reduce respondent time commitment, younger cohort twins (born 1964 – 1975) and spouses of older cohort twins were not readministered some interview items identical to their prior assessment.
