Effects of aerobic exercise training on cerebral pulsatile hemodynamics in middle-aged adults with elevated blood pressure/stage 1 hypertension.

Mechanisms behind the protective effects of aerobic exercise on brain health remain elusive but may be vascular in origin and relate to cerebral pulsatility. This pilot study investigated the effects of 12-wk aerobic exercise training on cerebral pulsatility and its vascular contributors (large artery stiffness, characteristic impedance) in at-risk middle-aged adults. Twenty-eight inactive middle-aged adults with elevated blood pressure or stage 1 hypertension were assigned to either moderate/vigorous aerobic exercise training (AET) for 3 days/wk or no-exercise control (CON) group. Middle cerebral artery (MCA) pulsatility index (PI), large artery (i.e., aorta, carotid) stiffness, and characteristic impedance were assessed via Doppler and tonometry at baseline, 6, and 12 wk, whereas cardiorespiratory fitness (V̇o2peak) was assessed via incremental exercise test and cognitive function via computerized battery at baseline and 12 wk. V̇o2peak increased 6% in AET and decreased 4% in CON (P < 0.05). Proximal aortic compliance increased (P = 0.04, partial η2 = 0.14) and aortic characteristic impedance decreased (P = 0.02, partial η2 = 0.17) with AET but not CON. Cerebral pulsatility showed a medium-to-large effect size increase with AET, although not statistically significant (P = 0.07, partial η2 = 0.11) compared with CON. Working memory reaction time improved with AET but not CON (P = 0.02, partial η2 = 0.20). Our data suggest 12-wk AET elicited improvements in central vascular hemodynamics (e.g., proximal aortic compliance and characteristic impedance) along with apparent, paradoxical increases in cerebral pulsatile hemodynamics.NEW & NOTEWORTHY We identify differential central versus cerebrovascular responses to 12 wk of aerobic exercise training in middle-aged adults. Although proximal aortic compliance and characteristic impedance improved after 12 wk of exercise, cerebral pulsatility tended to unexpectedly increase. These data suggest short-term aerobic exercise training may lead to more immediate benefits in the central vasculature, whereas longer duration exercise training may be required for beneficial changes in pulsatility within the cerebrovasculature.

Age-associated increases in middle cerebral artery pulsatility differ between men and women.

Mechanisms underlying sex differences in brain aging remain unclear but may relate to changes in cerebral pulsatile blood flow. Sex differences in the stiffening of the large arteries and expansion of pulse pressure with age may accelerate changes in pulsatile (i.e., discontinuous) blood flow in the brain that contribute to brain health. The purpose of this cross-sectional, secondary analysis was to examine sex differences in age-associated changes in large artery (aorta and carotid) stiffness, carotid pulse pressure, and cerebral pulsatility in 206 men and 217 women between 18 and 72 yr of age. Outcomes included aortic stiffness [carotid-femoral pulse wave velocity (cfPWV)] and carotid pulse pressure via tonometry, carotid ß-stiffness via ultrasound, and middle cerebral artery (MCA) pulsatility index via transcranial Doppler. Regression analyses revealed a significant age-by-sex interaction, with women exhibiting a slower rate of change compared with men for cfPWV (ß = -0.21, P = 0.04), and greater rate of change for carotid stiffness (ß = 0.27, P = 0.02), carotid pulse pressure (ß = 0.98, P < 0.001), and MCA pulsatility index (ß = 0.49, P = 0.002) after adjustment for covariates. The significant age-by-sex interaction for MCA pulsatility was abolished after further adjustment for carotid pulse pressure. Women exhibit accelerated increases in cerebral pulsatility during midlife, likely driven by exaggerated increases in carotid stiffness and pulse pressure compared with men. These data suggest that there are disproportionate increases in cerebral pulsatility in women during midlife that could contribute to accelerated brain aging compared with men.NEW & NOTEWORTHY We identify sex-specific associations between increasing age and cerebral pulsatility and its vascular mechanisms. When compared with men, women in our cross-sectional analysis exhibited greater age-associated increases in carotid stiffness, carotid pulse pressure, and cerebral pulsatility particularly during midlife. These data suggest that the rapid expansion of pulse pressure during midlife contributes to an exaggerated increase in cerebral pulsatility among women and suggest a potential mechanism contributing to sex differences in brain aging.