Cerebral blood flow and arterial transit time responses to home-based exercise training in healthy older adults

Brain vascular health worsens with age, evident by grey matter cerebral blood flow (CBFGM) reductions and lengthening arterial transit time (ATTGM). Exercise training can improve aspects of brain health in older adults, yet its effects on CBFGM and ATTGM remain unclear. This randomised controlled trial assessed responses of CBFGM and ATTGM to a 26-week home-based exercise intervention in 65 healthy older adults (control; n=33, exercise; n=32, aged 60–81 years), including whether changes in CBFGM or ATTGM were associated with cognitive function changes. Multi-delay pseudo-continuous arterial spin labelling data were used to estimate resting global and regional CBFGM and ATTGM. Results showed no between-group differences in CBFGM or ATTGM following the intervention. However, exercise participants with the greatest cardiorespiratory gains (n=17; ∆V̇O2peak>2 mL/kg/min) experienced global CBFGM reductions (-4.0 [-7.3, -0.8] mL/100 g/min). Furthermore, within the whole exercise group, cardiorespiratory fitness gains were associated with global CBFGM declines (β=-0.43 [-0.81, -0.04]), but no association was present with ATTGM. No changes in cognitive function or associations with CBFGM/ATTGM changes were observed. Our findings indicate exercise training in older adults may induce global CBFGM reductions, which are associated with the magnitude of cardiorespiratory fitness gains, but do not appear to affect cognitive function.