An important effort of the Baltimore Longitudinal Study of Aging (BLSA) is to identify predictors of cognitive morbidity, and to identify which cognitive processes are preserved with aging and which processes are vulnerable to disease. Cognitive test administered through this project are intended to provide insight into impairments associated with aging, most notably Alzheimer's disease (AD). Early markers or indicators of Alzheimer's disease have the potential to lead researchers to identify factors and therapies that are important in both preventing and reducing the risk for AD