Exercise Training Reduces Cerebrovascular Impedance in Patients with Amnestic Mild Cognitive Impairment: A 1-Year...

In patients with amnestic mild cognitive impairment (aMCI), cerebrovascular impedance modulus ( Z ) was higher than in cognitively normal peers, which is associated with brain hypoperfusion. While 1 yr of moderate-to-vigorous aerobic exercise training (AET) reduced Z in cognitively normal older adults, the effects of AET on aMCI remain unknown.

Seventy patients with aMCI were randomized into 1 yr of AET ( N = 31) or stretching and toning (SAT, N = 39). At baseline, midpoint (6 months), and trial completion (12 months), Z was assessed using transfer function analysis between carotid arterial pressure and cerebral blood flow (CBF) velocity measured simultaneously via applanation tonometry and transcranial Doppler in the middle cerebral artery, respectively. Total CBF was measured as the sum of the bilateral internal carotid and vertebral arterial flow via duplex ultrasonography.

The AET group exhibited gradual, significant reductions in Z at 6 months ( P = 0.008 vs baseline) and 12 months ( P < 0.001 vs baseline; P < 0.001 vs 6 months). In the SAT group, although Z decreased during the first 6 months ( P < 0.001 vs baseline), it was maintained over the following 6 months. Repeated-measures correlation analyses revealed inverse relationships between Z and total CBF as well as cerebrovascular conductance in the AET group ( rrm = -0.503, P = 0.008; rrm = -0.404, P = 0.037, respectively), but not in the SAT group. In exploratory sex-stratified analyses, women exhibited continued reductions in Z across 12 months regardless of training modality, whereas men demonstrated a plateau after 6 months.

These findings suggest that in patients with aMCI, AET reduces Z , which is associated with higher brain perfusion and cerebrovascular conductance. Sex-stratified analyses further suggested that women may experience greater improvements in Z than men across 1 yr of training.