Neurovascular coupling is impaired in slow walkers: the MOBILIZE Boston Study.

OBJECTIVE: Neurovascular coupling may be involved in compensatory mechanisms responsible for preservation of gait speed in elderly people with cerebrovascular disease. Our study examines the association between neurovascular coupling in the middle cerebral artery and gait speed in elderly individuals with impaired cerebral vasoreactivity.
METHODS: Twenty-two fast and 20 slow walkers in the lowest quartile of cerebral vasoreactivity were recruited from the MOBILIZE Boston Study. Neurovascular coupling was assessed in bilateral middle cerebral arteries by measuring cerebral blood flow during the N-Back task. Cerebral white matter hyperintensities were measured for each group using magnetic resonance imaging.
RESULTS: Neurovascular coupling was attenuated in slow compared to fast walkers (2.8%; 95% confidence interval [CI], -0.9 to 6.6 vs 8.2%; 95% CI, 4.7-11.8; p = 0.02). The odds ratio of being a slow walker was 6.4 (95% CI, 1.7-24.9; p = 0.007) if there was a high burden of white matter hyperintensity; however, this risk increased to 14.5 (95% CI, 2.3-91.1; p = 0.004) if neurovascular coupling was also attenuated.
INTERPRETATION: Our results suggest that intact neurovascular coupling may help preserve mobility in elderly people with cerebral microvascular disease.