Dementia in the elderly is a chronic syndrome with multiple causes that is already major public health burden and presents a clear therapeutic imperative to biomedical researchers. Given the time and expense of randomized clinical trials (RCTs) focused on preventing or delaying incident dementia, there is a critical public health need to validate therapies quickly and robustly to insure that the best possible candidates advance to RCTs. This application is a competitive renewal of Pharmaco- neuropathology of Brain Aging and Dementia that exploits the tremendous and unique resources of the Adult Changes in Thought Study, a large population-based longitudinal study of brain aging and incident dementia in older individuals, to identify potentially effective therapeutics for advancement to clinical trials. In this competitive renewal, we propose to determine the associations between the following mid- and late-life exposures or activities and neuropathologic, structural, and biochemical features of dementia in the elderly: "cardioprotective" doses of aspirin, hormone replacement therapy in women, two subclasses of antihypertensive drugs with proposed neuroprotective actions (calcium channel blockers and angiotensin-converting enzyme inhibitors), and level of physical exercise. These observational data will provide a unique perspective on which commonly prescribed drugs or exercise suppress specific mechanisms of disease, thereby guiding research on comparative effectiveness and aiding in the selection of regimens to pursue in RCTs.