Cerebral autoregulation, individual variability, and white matter hyperintensity (1069.1)

Abstract

Purpose: To assess regional cerebral autoregulation (CA) and its association with white matter hyperintensities (WMH) in older adults.Methods: Twenty‐seven healthy older subjects (13 females, 68 ± 6 yr) underwent fluid‐attenuated inversion recovery MRI to measure WMH. Cerebral blood flow (CBF) in the internal carotid (ICA) and vertebral arteries (VA) was measured using color‐coded duplex ultrasonography. CA was assessed during steady‐state changes in mean arterial pressure (MAP) from ‐11 ± 7% to 21 ± 8% (relative to baseline) and quantified by a linear regression slope between percentage changes in cerebrovascular resistance (CVR=MAP/CBF) and MAP. Multiple linear regression analysis was used to explore the relationship between regional CA and WMH.Results: Substantial individual CA variability was found in both ICA and VA with the regression slopes of CVR to MAP ranged from 0.366 to 2.198 in the ICA and from 0.172 to 3.175 in the VA. CA measured in the VA had a positive correlation (r = 0.741, P < 0.001) with periventricular WMH (PWMH), after adjustment for age, central arterial stiffness, sex and resting blood pressure. Of note, individuals with more PWMH (> 0.3 % intracranial volume) showed a hyper‐reactivity of CA (i.e., a paradoxical reduction in CBF during increases in arterial pressure) at the VA. Interpretation: Large individual CA variability exists in healthy older adults. The association between the hyper‐reactivity of posterior CA and PWMH suggests that the presence of small cerebral vessel disease may lead to hypoperfusion in the posterior cerebral circulation during acute increase in blood pressure.Grant Funding Source: NIH grant R01AG033106‐01 and R01HL102457.