In 1990, six COGA sites began recruitment of treated alcohol dependent subjects, as well as their first degree and extended family members, a number of whom were also alcohol dependent. Community-ascertained comparison families were also included. Both samples were administered the same broad assessment protocol, which included: a) a comprehensive interview (the Semi-Structured Assessment for the Genetics of Alcohol, SSAGA; Bucholz et al., 1994, 2006) that measures major psychiatric diagnoses, including drinking and substance use disorders, as well as key environmental domains such as childhood upbringing and peer substance use; and b) questionnaires that address a wide range of personal and environmental characteristics related to drinking (e.g., sensation seeking). In addition, participating families that were most genetically informative were genotyped and administered EEG/ERP protocols and neuropsychological tasks that tap addiction-relevant constructs (e.g., executive functioning, reward sensitivity; Begleiter et al., 1995). In 2005, COGA initiated an ongoing prospective study of adolescents and young adults (Bucholz et al., 2017). To date, over 17,000 subjects have participated in one or more phases of COGA. About half (53%) are female, and most ethnicities are represented (67% European ancestry, 23% African ancestry, 7% Hispanic, 1% Asian, 2% Other).
