WolfArticle presents data from the Framingham Heart Study, the longest-running prospective epidemiologic study in history, which was initiated in 1948 in response to the rising toll of coronary heart disease and hypertension. During the ensuing decades, the study of other diseases, notably stroke and dementia, was added. Clinical correlation with systematic neuropathological examinations of more than 150 brains has provided important confirmation of cerebrovascular and brain tissue indices of disease. Identification of persons at heightened risk for stroke, mild cognitive impairment, Alzheimer disease, and cognitive decline years prior to disease onset may facilitate delay in disease onset and prevention.