THE RELATIONSHIP BETWEEN BETA-AMYLOID AND VASCULAR HEALTH IN OLDER ADULTS

Abstract

To assess the relationship of beta-amyloid (Aβ) burden with peripheral vascular endothelial function and central cerebrovascular resistance among cognitively normal older adults. We enrolled eighty-three participants aged 65 to 87. Global Aβ burden was quantified using [18F] Florbetapir. All individuals classified as elevated had global Aβ burden >1.1 standard uptake value ratio (SUVR). Using Doppler ultrasound, we examined a measure of vascular endothelial function, brachial artery flow-mediated dilation (FMD). Cerebrovascular resistance measured by pulsatility index (PI) and middle cerebral artery blood flow velocities were recorded by transcranial Doppler ultrasound during 8 minutes of rest. White matter lesions (WML) total volume and count, common indices of cerebral small vessel health, were quantified by MRI. After adjusting for age and cardiovascular risk factors, there was a significant negative association between Aβ burden and FMD (p<0.01), such that for each 0.1 increase in Aβ burden, FMD decreased by 0.8%. Decreased brachial artery FMD response was found in individuals with elevated Aβ compared with the non-elevated group (p<0.01). The optimal cut point of FMD predicting Aβ elevation was 5% (AUC=0.836, p<0.01, 95%CI: 0.742 - 0.930), with 81.8% sensitivity and 75.4% specificity. Higher PI was demonstrated in elevated Aβ individuals (p=0.04), but was not correlated with Aβ burden. WML were not associated with Aβ.