Impaired consolidation of visuomotor adaptation in patients with multiple sclerosis.

BACKGROUND: Apart from inflammation and neurodegeneration, the individual clinical course of multiple sclerosis (MS) might be determined by differential adaptive capacities of the central nervous system. It has been postulated that the retention of adaptive training effects may be impaired in persons with MS (PwMS). OBJECTIVE: To investigate motor adaptation and consolidation capacities of people with MS in a visual motor adaptation task (VAT). METHODS: A total of 23 PwMS (Expanded Disability Status Scale (EDSS) score < 6) and 20 matched healthy controls were recruited. All participants completed three sessions of a VAT where a clockwise rotation angle of 30° was introduced as perturbation during the active learning part of the paradigm. The training session (T0 ) was repeated after 24 h (T1 ) and 72 h (T2 ). Directional errors and parameters of adaptation and retention were evaluated. RESULTS: PwMS showed similar adaptation and online learning abilities as controls. However, the retention ratio was significantly lower in patients compared to controls at T1 (p = 0.036) and T2 (p = 0.039). There was no significant correlation between the overall adaptation or retention ratio and the EDSS score, respectively. CONCLUSION: Our findings indicate intact adaptation, but limited consolidation, in patients with mild-to-moderate MS. Future studies are needed to define the neurobiological substrates of this plasticity and the extent to which it can influence clinical outcomes.