Aerobic capacity moderates the association between cervical cord atrophy and clinical disability in mildly disabled multiple sclerosis patients

Background: Spinal cord volume loss is associated with clinical disability in multiple sclerosis (MS). Aerobic capacity may mitigate the impact of central nervous system (CNS) damage accumulation, exerting beneficial effects on MS-related disability. Objectives: We investigated whether aerobic capacity could moderate the association between spinal cord atrophy and clinical disability in MS. Methods: In this cross-sectional analysis, expanded disability status scale (EDSS), peak of oxygen consumption (VO2peak), brain volumetric measures, and the normalized mean upper cervical cord area (nMUCCA) were collected from 51 MS patients and 33 healthy controls (HCs). Low aerobic capacity was defined as having a VO2peak z-score less than -1.64 standard deviations. In MS patients, we explored whether the association between nMUCCA and EDSS is moderated by the level of aerobic capacity. Results: The relationship between nMUCCA and EDSS was moderated by aerobic capacity, with a significant nMUCCA x aerobic capacity interaction (beta = -0.099, 95% bootstrapped confidence interval [CI] = [-0.172; -0.014], p = 0.012). Lower nMUCCA was significantly associated with higher EDSS score in MS patients with low aerobic capacity (beta = -0.073, p < 0.001), but not in those with high aerobic capacity (beta = 0.026, p = 0.417). Conclusions: In MS patients with mild disability, higher aerobic capacity can potentially mitigate the negative impact of spinal cord damage on clinical disability.