The Indianapolis Ibadan cohort was established in 1991 and is a longitudinal, prospective population-based comparative epidemiological study of the prevalence and incidence rates and risk factors for Alzheimer’s disease and other age associated dementias. The project compares samples of community-dwelling elderly (6770 subjects age >70 years) African Americans living in Indianapolis to Yoruba living in Ibadan, Nigeria. Blood samples for DNA were collected from all consenting participants. Cell lines and cell line DNA were obtained from a subset of subjects. Enrollment and data collection for this cohort is closed.