Healthy aging affects cerebrovascular reactivity and pressure-flow responses, but not neurovascular coupling: A cross-sectional study

• Published in: PloS one 2019-05, Vol.14 (5), p.e0217082-e0217082
• Main Authors: Stefanidis, Kayla B, Askew, Christopher D, Klein, Timo, Lagopoulos, Jim, Summers, Mathew J
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Adults; Age; Age Factors; Aged; Aging; Alcohol; Biology and Life Sciences; Blood; Blood flow; Blood Flow Velocity; Blood Pressure; Carbon dioxide; Cardiovascular disease; Cerebral blood flow; Cerebrovascular Circulation - physiology; Cerebrovascular disorders; Cognitive ability; Complications and side effects; Coronary vessels; Coupling; Cross-Sectional Studies; Dementia; Dementia disorders; Development and progression; Doppler effect; Earth Sciences; Ecology and Environmental Sciences; Family medical history; Female; Flow velocity; Healthy Aging - physiology; Heart; Hemodynamics; Humans; Hypercapnia; Hypocapnia; Male; Medicine and Health Sciences; Middle Aged; Middle Cerebral Artery - physiology; Neurosciences; Neurovascular Coupling - physiology; NMR; Nuclear magnetic resonance; Older people; People and Places; Physical Sciences; Pressure; Process parameters; Reactivity; Research and Analysis Methods; Risk factors; Stroke; Studies; Ultrasonic imaging; Ultrasound; Young Adult; Young adults
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0217082

Aging leads to alterations in cerebrovascular function, and these are thought to contribute to cognitive decline/dementia. Disturbances to cerebral blood flow regulation have been reported, but the findings are inconsistent and to date no study has comprehensively tested the collective and independent contribution of these parameters in the same age range. Such lines of enquiry are vital since aging is a heterogeneous and complex process, with cerebrovascular parameters being differentially affected depending on the individual. A multicomponent comprehensive measure of cerebrovascular function, which accounts for such diversity, is needed to differentiate between healthy young and old adults. We tested the effect of aging on cerebrovascular function by comparing healthy young adults aged 18-30 and older adults aged 60-75, without cognitive impairments. Cerebrovascular blood flow velocity was assessed using transcranial Doppler ultrasound. Parameters included resting middle cerebral artery velocity (MCAv), neurovascular coupling, cerebrovascular reactivity to CO2 (hypercapnia and hypocapnia), and the pressure-flow response during a sit-to-stand procedure. MANOVA revealed that collectively, the parameters discriminated the groups (p < .001). MCAv and pressure-flow responses were lower in the older group (p < .001). While there were no differences in hypercapnic responses (p = .908) and neurovascular coupling (p = .517), hypocapnic responses were elevated in the old (p = .002). Collectively, cerebrovascular parameters can distinguish between healthy young and older adults, with aging leading to reductions in MCAv, and altering cerebrovascular reactivity and pressure-flow responses under hypotensive conditions.