One-Year Aerobic Exercise Reduced Carotid Arterial Stiffness And Increased Cerebral Blood Flow In Amnestic Mild Cognitive Impairment

Background: Central arterial stiffness and brain hypoperfusion are emerging risk factors of Alzheimer's disease (AD). Aerobic exercise training (AET) may improve central arterial stiffness and brain perfusion.Objective: To investigate the effects of AET on central arterial stiffness and cerebral blood flow (CBF) in patients with amnestic mild cognitive impairment (MCI), a prodromal stage of AD.Methods: This is a proof-of-concept, randomized controlled trial that assigned 70 amnestic MCI patients into a 12-month program of moderate-to-vigorous AET or stretching-and-toning (SAT) intervention. Carotid beta-stiffness index and CBF were measured by color-coded duplex ultrasonography and applanation tonometry. Total CBF was measured as the sum of CBF from both the internal carotid and vertebral arteries, and divided by total brain tissue mass assessed with MRI to obtain normalized CBF (nCBF). Episodic memory and executive function were assessed using standard neuropsychological tests (CVLT-II and D-KEFS). Changes in cardiorespiratory fitness were measured by peak oxygen uptake ((V)over dotO(2peak)).Results: Total 48 patients (29 in SAT and 19 in AET) were completed one-year training. AET improved (V)over dotO(2peak), decreased carotid beta-stiffness index and CBF pulsatility, and increased nCBF. Changes in (V)over dotO(2peak) were associated positively with changes in nCBF (r = 0.388, p = 0.034) and negatively with carotid beta-stiffness index (r = -0.418, p = 0.007) and CBF pulsatility (r = -0.400, p = 0.014). Decreases in carotid beta-stiffness were associated with increases in cerebral perfusion (r = -0.494, p = 0.003). AET effects on cognitive performance were minimal compared with SAT.Conclusion: AET reduced central arterial stiffness and increased CBF which may precede its effects on neurocognitive function in patients with MCI.