Vascular risk profiles for dementia and Alzheimer's disease in very old people: a population-based longitudinal study.

Numerous studies have linked individual vascular factors to dementia including Alzheimer's disease (AD). We investigated different vascular risk profiles in relation to dementia and AD among very old people. A standardized follow-up procedure was applied three times to a dementia-free cohort (n=1270, age >or= 75) over a nine-year period to detect dementia and AD cases using the DSM-III-R criteria. We examined two vascular risk profiles, which were scored by counting the number of corresponding vascular factors: 1) atherosclerotic profile included systolic pressure >or= 160 mmHg, diabetes/prediabetes, and stroke; and 2) cerebral hypoperfusion profile constituted diastolic pressure < 70 mmHg, pulse pressure < 70 mmHg, and heart failure. Data were analyzed with Cox proportional-hazards models controlling for major potential confounders. During the 6406 person-years of follow-up, 428 subjects developed dementia, including 328 AD cases. All components of vascular profiles were significantly or marginally associated with increased dementia risk. The risk of dementias was increased with increasing score of both risk profiles (p for trend <or= 0.001); subjects with a score >or= 2 in either profile had an approximately twofold-increased risk for dementia and AD. These data suggest that aggregation of atherosclerotic- and hypoperfusion-related vascular factors increases the risk of dementia in very old people. Severe cerebral atherosclerosis and insufficient perfusion are involved in the development of dementia including AD.