Vascular Health is Associated with Amyloid-β in Cognitively Normal Older Adults

Background: Vascular health is closely related to Alzheimer's disease (AD). Vascular function measured by flow mediated dilation (FMD) or pulsatility index (PI) can be used as marker of peripheral and central vascular health but is poorly characterized in those at risk for AD. Objective: To assess the relationship of peripheral and central vascular function with amyloid-beta (A beta) and white matter lesion burden among cognitively normal older adults. Methods: We enrolled participants 65 years of age and older. Using Doppler ultrasound, we assessed brachial artery FMD, and middle cerebral artery (PI). Global A beta burden, quantified using [18F] Florbetapir PET imaging, and white matter lesion volume (WML) were used as measures of AD pathology and vascular brain injury. Results: After adjusting for age and cardiovascular risk factors, the data (n = 83) showed a negative association between FMD and A beta burden (beta = -0.03, p < 0.001). FMD at a cut-off of 4.45% had 88% specificity and 75% sensitivity to elevated A beta (AUC = 0.86, 95% CI: 0.77-0.95). FMD was not related to WML volume (p = 0.8), and PI was unrelated to A beta burden or WML volume (0 > 0.4). Conclusions: Among cognitively normal older adults, blunted peripheral vascular function, as measured by brachial artery FMD, is associated with A beta burden. These findings provide support for further exploration into the pathophysiological relationship of vascular health and AD risk as measured by A beta.