The Minority Aging Research Study (MARS) is a longitudinal, epidemiological cohort study of decline in cognitive function and risk of Alzheimer’s disease in older African-Americans. MARS began in 2004 and over 600 persons have enrolled, 560 of which are currently alive. The study enrolls African-American men and women over age 65 that haven’t been diagnosed with dementia. After consent is obtained, a baseline evaluation is scheduled and performed in the participant’s home. At the baseline visit, a uniform, structured clinical evaluation is completed consisting of an interview to ascertain a variety of lifestyle and experiential risk factors, a neurological examination, a blood draw, and a comprehensive neuropsychological battery of 23 cognitive tests. The clinical evaluation is repeated on an annual basis. The autopsy program is offered to all subjects as well but not required. Participants also have yearly blood draws which result in the storage of serum, plasma and cells.