Indices of cerebral vascular function & health in young healthy adults: impact of sex and race
Authors: Kolade John O. , Perry Ken A. , Ortiz Alison , Shah Prarthi J. , Liao Yue , Brothers R. Matthew 
Published: May 2024

Background: Cerebral vascular diseases and neurocognitive conditions including stroke, cognitive impairment, & Alzheimer’s disease and related dementias are the fastest growing causes of morbidity and mortality. Studies have demonstrated sex differences in indices of physiological function associated with cardiovascular and metabolic disease risk/prevalence. Further, the incidence of these conditions is elevated in Black (BL) individuals; however, BL females have a reduced age adjusted stroke mortality compared to BL males. Reduced cerebral vascular function/health contributes to the risk for these conditions. Limited studies have examined the influence of sex and race on indices of cerebral vascular function/health. This study examined the potential interaction between race and sex in cerebral pulsatility index (PI: index of cerebral vascular stiffness) and cerebral vasomotor reactivity (CVMR) to a hypercapnic challenge (index of cerebral vasodilatory responsiveness). Hypothesis: We hypothesized: 1) females would have reduced PI and elevated CVMR relative to males. 2) BL individuals would exhibit augmented PI and reduced CVMR. 3) BL females would have reduced PI relative to BL males. 4) Lastly, we posit that CVMR will be negatively correlated with PI. Methods: Data is presented from 136 young healthy individuals. 40 BL males (age: 22±3 yr, BMI: 25±4 kg/m²), 37 BL females (age: 21±3 yr, BMI: 24±4 kg/m²), 39 White (WH) males (age: 24±3 yr, BMI: 25±3 kg/m²), and 20 WH females (age: 25±6 yr, BMI: 23±3 kg/m²). Heart rate, beat-to-beat blood pressure, end-tidal carbon dioxide concentration (PETCO2), and middle cerebral artery blood velocity (MCAv) were continuously recorded (minimum of 6 min). Cerebral vascular function/health was indexed as (a) PI ((MCAVv systolic − MCAv diastolic)/MCAv mean). (b) CVMR assessed as % increase in cerebral vascular conductance (CVCi) slope during a hypercapnic challenge (%CVCi/ΔPETCO2). Results: PI was elevated in males (male: 0.86±0.18, female: 0.77±0.11, P=0.03). There was no difference between races (WH: 0.83±0.19, BL: 0.79±0.13, P=0.27) nor was there a sex x race interaction ( P=0.54). CVMR assessed as %CVCi slope was not different between sexes (male: 2.4±1.7 %/mmHg, female: 2.7±1.2 %/mmHg, P=0.16) or BL & WH (WH: 2.7±1.3 %/mmHg, BL: 2.4±1.1 %/mmHg, P=0.16). CVMR was lower in the BL males relative to the BL females (BL male: 2.0±0.9 %/mmHg, BL female: 2.8±1.2 %/mmHg, P=0.002). There was no difference between WH males and females ( P=0.88). Lastly, there was not a significant correlation between PI and CVMR to hypercapnia ( P=0.16). Conclusion: These preliminary data suggest that relatively young and otherwise health White and Black females have augmented indices of cerebral vascular function/health relative to males. Furthermore, BL males have reduced cerebral vasodilatory responsiveness to a hypercapnic stimuli. The University of Texas at Arlington College of Nursing and Health Innovation and Institutional Start up Funds to Dr. Brothers. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.