Effects of 1‐year Aerobic Exercise Training on Cerebral Blood Flow and Arterial Siffness in Amnestic Mild Cognitive Impairment

Abstract

Aerobic exercise training (AET) may improve cerebralperfusion and reduce the risk of dementia. Changes in central arterialstiffness and pulsatile cerebral blood flow (CBF) associated with exercise training may be one of the underlying pathophysiological mechanism. The purpose of this study was to investigate: (1) The effects of AET on central arterialstiffness and CBF, and (2) whether pulsatile CBF mediates the association between changes in arterial stiffness and cerebral perfusion in amnestic mildcognitive impairment (aMCI), a prodromal stage of Alzheimer disease. Seventy aMCI patients were randomized to 12 months of moderate‐intensity AET (n=31) or stretching program (n=39). CBF and carotid β‐stiffness index were assessed by ultrasonography and applanation tonometry. Cerebral perfusion was calculated by normalizing total CBF to brain tissue mass measured by magnetic resonance imaging. Pulsatile CBF was measured from the middle cerebralartery using transcranial Doppler. Cardiorespiratory fitness was assessed by peak oxygen uptake (VO2peak). VO2peak and cerebralperfusion increased and carotid β‐stiffness index decreased in the AET group, while remained unchanged in the stretching group. The change in VO2peak was significantly associated with the change in cerebral perfusion, carotidβ‐stiffness index, and pulsatile CBF (Fig. 1). The decrease in carotidβ‐stiffness was associated with increased in cerebral perfusion (Fig. 2). Mediation analysis showed that changes in pulsatile CBF mediates the association between carotidβ‐stiffness index and cerebral perfusion (Fig. 2). These results suggest that AET decreases arterial stiffness and increases cerebral perfusion, which is mediated by pulsatile CBF in aMCI patients.Support or Funding InformationThis work was funded by the National Institutes of Health ((R01AG033106, R01HL102457, P30AG012300)Associations between the change (Δ) in relative peak oxygen uptake (VO2) and the change in cerebral perfusion, carotid β‐stiffness index and pulsatile cerebral blood flow (CBF).Figure 1Mediation analysis diagram of the effect of the change (Δ) in carotid β‐stiffness index on the change in cerebral perfusion through the change in pulsatile cerebral blood flow (CBF).Figure 2