Relationship between blood pressure during middle age and cognitive impairment in old age: The western collaborative group study

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Abstract
We examined the relationship between blood pressure levels measured during middle age when few, if any, study participants were taking antihypertensive medication and incidence of global cognitive impairment 25 to 30 years later. Beginning in 1960-1961, blood pressure was assessed biannually through 1969-1970 when subjects were, on average, 45 years of age. Also assessed were educational attainment, central obesity and a variety of cardiovascular risk factors. During 1986-1988 and again at 1992-1994, 1,173 surviving male subjects (mean age = 75 years) were reexamined and assessed for cognitive performance using standard neuropsychological measures. Cognitive impairment was defined on the basis of test performance, self-report of dementia, or death or disease due to dementia. This definition resulted in 91 cases of impairment from 1986 to 1994 (an average per year incidence of 1.4%). Separate multiple logistic regression analyses, using either systolic or diastolic blood pressure measured during middle age as predictors of cognitive impairment, identified a significant relationship for both systolic blood pressure, relative risk (RR) = 1.35, 95% confidence interval (CI) = 1.08, 1.69, and diastolic blood pressure, RR = 1.31, 95% CI = 1.01, 1.70, after adjustment for age, education, and central obesity and exclusion of participants with stroke. These results suggest that higher levels of blood pressure measured during middle age are predictive of the incidence of cognitive impairment in old age.