The overall methodologies and design of the IAS have been previously described [Yates et al., 1998; Philibert, 2006]. In the latest wave of the studies, the subjects were re-interviewed with an extensive environmental, cognitive and behavioral assessment battery that included the Semi-Structured Assessment for the Genetics of Alcoholism, version 2 (SSAGA-II [Bucholz et al., 1994]) and phlebotomized to provide biomaterial for cell lines and DNA. Symptom counts and categorical diagnoses for MD and AD were derived from SSAGA-II data using criteria from the DSM-IV [Association, 1994] and our previously described methods [Yates et al., 1998]. Briefly, lifetime history of AD was defined as having met three or more criteria in the current or past wave of SSAGA interviews. Lifetime history of MD was defined as having met five or more criteria of a MD episode, including low mood or anhedonia, in the current or past wave of SSAGA interviews. Current MD is defined as having low mood or anhedonia and four other symptoms at the time of the phlebotomy draw. All procedures and protocols described in this communication were approved by the University of Iowa Institutional Review Board.
