Blood pressure and late-life cognitive function change: a biracial longitudinal population study

Abstract

Objective: To examine the relation of blood pressure (BP) to subsequent decline in cognitive function among persons age 65 or over.

Methods: All persons age 65 or over in a geographically defined community were invited to participate in a longitudinal study of problems of the elderly. Interviews were conducted in the participants' homes and included two BP measures and four tests of cognitive function. Follow-up interviews 3 and 6 years after baseline repeated the cognitive function tests. These analyses included 4,284 individuals who had baseline and at least one follow-up measure of cognitive function. The average of z scores of the individual cognitive function tests was used as a global measure of cognitive function.

Results: In random effects analyses controlling for age, sex, education, and race, there was no significant linear association of either systolic or diastolic BP with 6-year change in global cognitive function score. There was no significant curvilinear association with systolic BP. In tests for a curvilinear association with diastolic BP, there was a suggestion of increased decline among those with low or high diastolic BP (p = 0.03 for the quadratic diastolic term). At baseline, 50% of participants took some type of medication affecting BP.

Conclusion: In this community population where BP treatment was common, there was no association of either high systolic or high diastolic BP at the beginning of the observation interval with 6-year cognitive decline.