Blood pressure is associated with higher brain amyloid burden and lower glucose metabolism in healthy late middle-age persons

Abstract

Epidemiological studies suggest that elevated blood pressure (BP) in midlife is associated with increased risk of Alzheimer's disease (AD) in late life. In this preliminary study, we investigated the extent to which BP measurements are related to positron emission tomography (PET) measurements of fibrillar amyloid-beta burden using Pittsburgh Compound-B (PiB) and fluorodeoxyglucose (FDG) PET measures of cerebral metabolic rate for glucose metabolism (CMRgl) in cognitively normal, late middle-aged to older adult apolipoprotein E (APOE) ε4 homozygotes, heterozygotes and noncarriers. PiB PET results revealed that systolic BP (SBP) and pulse pressure (PP) were each positively correlated with cerebral-to-cerebellar PiB distribution volume ratio (DVR) in frontal, temporal, and posterior-cingulate/precuneus regions, whereas no significant positive correlations were found between PiB distribution volume ratios and diastolic BP (DBP). FDG PET results revealed significant inverse correlations between each of the BP measures and lower glucose metabolism in frontal and temporal brain regions. These preliminary findings provide additional evidence that higher BP, likely a reflection of arterial stiffness, during late midlife may be associated with increased risk of presymptomatic AD.

Figure 1

Statistical brain maps showing correlations between higher Pittsburgh Compound-B PET measurements of fibrillar amyloid-β burden and (A) higher systolic blood pressure, (B) higher pulse pressure (p < 0.05, uncorrected for multiple comparisons) in cognitively normal adults. No significant positive correlations were found between PiB measurements and higher diastolic blood pressure.

Figure 2

Statistical brain maps showing the correlations between lower CMRgl and (A) higher systolic blood pressure, (B) higher diastolic blood pressure, and (C) higher pulse pressure and (p < 0.005, uncorrected for multiple comparisons) are shown in dark and light blue. These statistical maps are projected onto the lateral and medial surfaces of the left and right cerebral hemispheres and shown in relationship to brain regions preferentially affected by AD (Alexander et al., 2002), which are shown in dark blue and purple. The dark blue areas thus reflect significant correlations between higher blood pressure measurements and lower CMRgl in the brain regions that are preferentially affected by AD.