Between 1988 and 1998, investigators at six COGA sites used a common protocol to gather clinical information and biological data (including DNA and neurophysiologic measures) from families of subjects with alcoholism. Participants were recruited among patients undergoing alcoholism treatment (i.e., the probands) and their first-degree relatives. Control families were recruited from dental clinics, motor vehicle records, or random mailings at the six sites. Control families were not excluded if a family member had alcoholism or another psychiatric disorder; thus, these families represent a comparison group not selected with respect to psychopathology. Each control family included at least two parents and three children ages 14 and older. All participants were interviewed using a screening instrument called the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) (Bucholz et al. 1994), which allows for diagnostic assessment of various disorders, including alcoholism and depression.
