Optimal Blood Pressure for Cognitive Function

Findings From an Elderly African-American Cohort Study

Hai Liu, PhD; Gao, PhD; Kathleen S. Hall, PhD; Frederick W. Unverzagt, PhD; Kathleen A. Lane, MS; Christopher M. Callahan, MD; Hugh C. Hendrie, DSc

Disclosures

J Am Geriatr Soc. 2013;61(6):875-881. 

In This Article

Abstract and Introduction

Abstract

Objectives To report the results from a prospective cohort study on the association between blood pressure (BP) and cognitive function in elderly African Americans.

Design Prospective cohort study conducted from 1997 to 2009.

Setting Community-based study in Indianapolis.

Participants African Americans aged 65 years or older (N = 3,145).

Measurements At each assessment, participant cognitive function was measured using the Community Screening Interview for Dementia. Other measurements included BP, height, weight, education level, antihypertensive medication use, alcohol use, smoking, and history of chronic medical conditions.

Results Longitudinal assessments (n = 5,995) contributed by 2,721 participants with complete independent variables were analyzed using a semiparametric mixed-effects model. Systolic BP (SBP) of approximately 135 mmHg and diastolic BP (DBP) of approximately 80 mmHg were associated with optimal cognitive function after adjusting for other variables (P = .02). Weight loss with body mass index < 30.0 kg/m2 was significantly related to poorer cognitive performance (P < .001). Older age at first assessment, lower education level; smoking; and history of depression, stroke, and diabetes mellitus were related to worse cognitive function; taking antihypertensive medication and drinking alcohol were associated with better cognitive function.

Conclusion High and low BP were associated with poorer cognitive performance. A joint optimal region of SBP and DBP for cognitive function has been identified, which may provide useful clinical information on optimal BP control in cognitive health and lead to better quality of life for elderly adults.

Introdcution

Most previous reports have found that maintenance of high cognitive function is a prerequisite for successful aging.[1] There is extensive literature suggesting that hypertension in midlife is a risk factor for cognitive impairment and dementia in elderly adults and that treatment with antihypertensive medication reduces this risk,[2–6] but there is uncertainty about the relationship between late-life blood pressure (BP) and cognitive performance in elderly adults.[7,8] Some studies report a positive association between high BP and cognitive impairment, but very low BP has also been linked with poorer cognitive function.[9–12] More-recent reports have found a U-shaped relationship between systolic BP (SBP) and cognitive function, suggesting that high and low SBP (e.g., ≥160 or <130 mmHg) are related to poorer cognitive performance, but this relationship did not hold for diastolic BP (DBP).[13,14] Because of these inconsistencies, the clinical determination of what might be optimal BP to maintain in elderly adults to protect against the risk of cardiovascular and cerebrovascular diseases and yet maintain good cognitive function is uncertain.[7]

Previous studies have examined the effects of SBP and DBP on cognitive function in separate models, preventing the exploration of the joint relationship between these two types of BP and cognitive function.[15,16] African Americans are known to have a higher prevalence of hypertension than other ethnic groups.[17,18] Knowledge of the relationship between BP and cognitive function in African Americans has been limited. This article examines the joint relationship between SBP and DBP and cognitive performance in a cohort of elderly community-dwelling African Americans followed for up to 12 years.

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