Effects of Race on Dynamic Cerebral Autoregulation in Elderly People

Abstract

Race is known to affect cardiovascular dynamics, but no research has examined cerebrovascular dynamics. Therefore, we retrospectively examined measures of cerebral autoregulation in a group of elderly individuals recruited into the population‐based MOBILIZE Boston Study.Of 765 community‐dwelling volunteers that were recruited for the MOBILIZE Boston study, cerebral flow velocity measures were obtained on 451 individuals (78±5 yrs) of which self reported race was African American ‐ AA (43), White (385) and Other (23). Cerebral flow velocity (TCD), beat‐by‐beat blood pressure (Finapres) and end‐tidal CO2 (capnography) were measured during a sit to stand maneuver and while seated.Race was associated with significant differences in Phase in both the 0.04–0.07 Hz range (AA: 28±41°, White: 46±34°, Other: 55±28°, p<0.05) and 0.07–0.15 Hz range (AA: 7±57°, White: 39±42°, Other: 33±33°, p<0.01). In contrast there was no difference in Gain or Coherence values. Autoregulatory Index was similar across groups (AA: 5.3±2.8, White: 4.8±2.5, Other: 5.0±2.2) as was CO2 Vasoreactivity (AA: 3.0±0.8, White: 3.0±0.7, Other: 3.0±0.7 %/mmHg). We controlled for age, diabetes, hypertension and prescription drugs.Our preliminary data suggest that race may be an important factor to consider in understanding cerebral autoregulation. The finding that AA had reduced phase suggests impaired autoregulation and may partially explain the increased risk of cerebrovascular events in AA. However, future work is necessary using larger numbers to validate our findings.