Myelin status is associated with change in functional mobility following slope walking in people with multiple sclerosis

BACKGROUND: The level of myelin disruption in multiple sclerosis patients may impact the capacity for training-induced neuroplasticity and the magnitude of therapeutic response to rehabilitation interventions. Downslope walking has been shown to increase functional mobility in individuals with multiple sclerosis, but it is unclear if myelin status influences therapeutic response. OBJECTIVE: The current study aimed to examine the relationship between baseline myelin status and change in functional mobility after a walking intervention. METHODS: The Timed Up and Go test was used to measure functional mobility before and after completion of a repeated, six-session slope walking intervention in 16 participants with relapsing–remitting multiple sclerosis. Multi-component T(2) relaxation imaging was used to index myelin water fraction of overall water content in brain tissue compartments. RESULTS: Results demonstrated that the ratio of the myelin water fraction in lesion to normal-appearing white matter (myelin water fraction ratio) significantly predicted 31% of the variance in change in Timed Up and Go score after the downslope walking intervention, where less myelin disruption was associated with greater intervention response. CONCLUSIONS: Myelin water content fraction ratio may offer a neural biomarker of myelin to identify potential responders to interventions targeting functional impairments in multiple sclerosis.