The Austrian Stroke Prevention Study is a community-based cohort study on the effects of vascular risk factors on brain structure and function in elderly participants without a history or signs of stroke and dementia on the inhabitants of Graz, Austria.  8193 individuals aged 50 to 75 years, stratified by sex and 5-year age groups, were randomly selected from the official community register.  Overall, 2794 of the invited subjects returned a card stating their willingness to participate. Recruitment into the study was stopped after enrollment of 2000 eligible participants. They were all white and of Central European origin. Individuals were excluded from the study if they had a history of neuropsychiatric disease, including previous cerebrovascular attacks and dementia, or an abnormal neurological status determined on the basis of a structured clinical interview and a physical and neurological examination.  Every fourth study participant, or in case of refusal the next participant, was invited to enter phase II of the study, which included MRI and Doppler sonography.