The MAP is a clinical-pathologic study that enrolled participants without known dementia. The study primarily enrolled residents of continuous care retirement communities. From September of 1997 through to April of 2005, more than 1,000 older persons without known dementia from more than 30 residential facilities across the Chicago metropolitan area agreed to participate, and 952 of them completed their baseline clinical evaluation. Of those 952, the mean age was 80.7 years, mean education was 14.4 years, 27.9% were male, and 91.7% were non-Hispanic and white. A third of participants had 12 or fewer years of education, and 60% had fewer than 16 years.