The ARIC MRI and Neurocognitive Longitudinal Study, is an ancillary study to the Atherosclerosis Risk in Communities (ARIC) Study and is funded by the National Heart Lung and Blood Institute (NHLBI). This study is designed to learn more about risk factors related to progression of brain abnormalities and how progression may relate to clinical outcomes such as cognitive decline and stroke. Brain morphology can be readily visualized using magnetic resonance imaging, or MRI, making it possible to detect and quantify changes in the brain's structure and vasculature. However, little is known about what factors influence brain changes and whether those changes have any prognostic significance. At the third ARIC visit (1993-1995) a sample of men and women 45-64 years old in Forsyth County NC and Jackson MS underwent an MRI scan. This study will repeat the MRI scans, add new volumetric measurements of selected brain regions, and reassess cognitive functioning in the original ARIC MRI cohort.