Sex differences in cerebrovascular function across an aerobic exercise intervention in older adults using MRI: Results from the Brain in Motion study

Sex differences in cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) with aging, and across an aerobic exercise training intervention are poorly understood. The primary aim of this study was to investigate sex differences in cerebrovascular function in brain regions involved in verbal fluency, across an aerobic exercise intervention. CBF and CVR were assessed in 27 Brain in Motion study participants before, and after a 6-month aerobic exercise intervention. Resting CBF was measured using arterial spin labeling (ASL) magnetic resonance imaging (MRI) while CVR was quantified using blood oxygen level dependent (BOLD) MRI and a hypercapnic challenge. Compared to pre-intervention values, VȮ₂peak increased (p<0.001) while whole brain cerebrovascular measures were unchanged (all p>0.05). There was no effect of the intervention or sex on CVR in the hippocampus, insula or left pars triangularis. There was a sex and intervention interaction in hippocampal, insula, and left pars triangularis blood flow (p<0.05). These findings provide evidence of sex differences in regions of the brain involved in verbal fluency in response to an aerobic exercise intervention.