—To assess the long-term relationship of midlife blood pressure levels to late-life cognitive function.
—The 4678 surviving cohort members of the prospective Honolulu Heart Program (baseline, 1965-1968) were examined a fourth time in 1991 through 1993 and given a cognitive test.
—The subjects were 3735 Japanese-American men living in Hawaii in the community or in institutions, with an average age of 78 years at the fourth examination.
Main Outcome Measures.
—Cognitive function, measured by the 100-point Cognitive Abilities Screening Instrument (CASI), was categorized into good (reference: a CASI score of 92 to 100), intermediate (<92 to 82), and poor (<82). Midlife systolic blood pressure (SBP) and diastolic blood pressure (DBP) values were measured in 1965,1968, and 1971. A respondent was classified into the following categories if two of three measurements fell into the following groups: for SBP, <110, 110 to 139, 140 to 159, and ≥160 mm Hg; and for DBP, <80, 80 to 89, 90 to 94, and ≥95 mm Hg.
—When we controlled for age and education, the risk for intermediate and poor cognitive function increased progressively with increasing level of midlife SBP category (P for trend <.03 and <.001, respectively). For every 10—mm Hg increase in SBP there was an increase in risk for intermediate cognitive function of 7% (95% confidence interval [CI], 3% to 11%) and for poor cognitive function of 9% (95% CI, 3% to 16%). Adjustment for prevalent stroke, coronary heart disease, and subclinical atherosclerosis reduced the strength of the relationship between midlife SBP and poor cognitive function to 5% (95% CI, 0% to 12%). The level of cognitive function was not associated with midlife DBP.
—Midlife SBP is a significant predictor of reduced cognitive function in later life. Early control of SBP levels may reduce the risk for cognitive impairment in old age.(JAMA. 1995;274:1846-1851)