We invited 1904 subjects aged between 60 and 90 years who were randomly selected in strata of age (5-year strata), sex, and study from a larger pool of subjects in the appropriate age groups from the 2 primary studies. Of these 1904 individuals, 1717 subjects were eligible. Details concerning the Rotterdam Scan Study have been published previously.19,20 Briefly, 1904 randomly selected subjects were invited by letter and subsequently contacted by telephone. On agreement of participation, a list of contraindications (dementia, contraindications for magnetic resonance imaging [MRI] scanning, blindness) was reviewed to assess eligibility. Dementia assessment was done by an initial screening of cognitive functions (using the Mini-Mental State Examination [MMSE21] and the Geriatric Mental Schedule, organic section).21 Those who scored below the cut-off of 26 on the MMSE or above 0 on the Geriatric Mental Schedule were further evaluated by more extensive neuropsychological tests, and, if indicated, informant interview and review of medical records. Among the eligible participants, 1077 (63%; 563 from the Rotterdam Study, 514 from the Zoetermeer Study) agreed to have an MRI brain scan and were included in these analyses. Responders differed from nonresponders in that they were younger, more educated (5% more subjects had a university-level education, P = .05), and had higher baseline MMSE scores (age and sex-adjusted mean difference, 0.4 points, P < .001), but equal cholesterol levels, body mass indexes, and blood pressure measurements.21 The medical ethics committee of the Erasmus University, Rotterdam, approved the protocol, and each participant signed an informed consent form.