Blood pressure and brain injury in older adults: findings from a community-based autopsy study

Abstract

Objectives: To examine correlations between blood pressure (BP) and dementia-related pathological brain changes in a community-based autopsy sample.

Design: Prospective cohort study.

Setting: A large health maintenance organization in Seattle, Washington.

Participants: A cohort of 250 participants aged 65 and older and cognitively normal at time of enrollment in the Adult Changes in Thought (ACT) Study and who underwent autopsy.

Measurements: BP and history of antihypertensive treatment were taken at enrollment. A linear regression model was used to examine the relationship between BP (systolic (SBP) and diastolic (DBP)) at enrollment and pathological changes in the cerebrum (cystic macroscopic infarcts, microinfarcts, neuritic plaques, neurofibrillary tangles, and cortical Lewy bodies).

Results: The presence of more than 2 microinfarcts, but not any other pathological change, was independently associated with SBP in younger participants (65-80, n=137) but not in older participants (>80, n=91). The relative risk (RR) for more than two microinfarcts with each 10-mmHg increase in SBP was 1.15 (95% confidence interval (CI)=1.00-1.33) in the younger participants, adjusted for age at entry, sex, and time to death. This RR was particularly strong in younger participants not taking antihypertensive medications (RR=1.48, 95% CI=1.21, 1.81); significant associations were not observed in participants treated for hypertension. Findings for DBP were negative.

Conclusion: The association between high SBP and cerebrovascular damage in untreated older adults (65-80) suggests that adequate hypertension treatment may reduce dementia risk by minimizing microvascular injury to cerebrum.

Figure 1

Box plots of systolic blood pressure in participants aged 65 to 80 years, by presence of > 2 microinfarcts and by presence of at least one cystic infarct. Boxes represent 50% of the data with the horizontal bar denoting the median. Data points outside the “whiskers” are considered outliers. A scatterplot of systolic blood pressure by jittered vascular pathology category is overlaid.

Figure 2

Box plots of systolic blood pressure entry in participants aged 65–80 years, by presence of > 2 microinfarcts and by antihypertensive treatment at study entry. Boxes represent 50% of the data with horizontal bar denoting the median. Data points outside the “whiskers” are considered outliers. A scatterplot of systolic blood pressure by jittered treatment/pathology category is overlaid.