Participants of the GenerAAtions Study were identified through the electronic claims database of the Henry Ford Health System. Community-dwelling African Americans aged 65 and older who had at least one encounter with the Henry Ford Health System in the three years prior to their recruitment and who had an available proxy informant were eligible for this study. Cases met NINCDS-ADRDA criteria for possible or probable AD, determined in a consensus conference which included a behavioral neurologist, psychiatrist, neuropsychologist, and a behavioral neurology nurse practitioner. Phenotypic data were available for 242 AD cases and 204 cognitively normal controls.