Efficacy of high-intensity aerobic exercise on cognitive performance in people with multiple sclerosis: A randomized controlled trial

Background: Cognitive impairment is highly prevalent in multiple sclerosis (MS). Progressive aerobic exercise (PAE) represents a promising approach toward preservation or even improvement of cognitive performance in people with MS (pwMS). Objective: To investigate the effects of PAE on the cognitive domains of information processing, learning and memory, and verbal fluency in pwMS. Methods: This randomized controlled trial included an exercise (n = 43, 24 weeks of supervised PAE, followed by self-guided physical activity) and a waitlist group (n = 43, 24 weeks of habitual lifestyle, followed by supervised PAE). Assessments included the Brief Repeatable Battery of Neuropsychological tests (BRB-N), self-reported mood, and cardiorespiratory fitness. Published reference data were used to compute Z-scores for BRB-N scores. Cognitive impairment was defined as one or more Z-scores ⩽ –1.5SD. Results: No between-group changes in the total group were observed in BRB-N scores following PAE. In the cognitively impaired subgroup (43% of the total group) the between-group point estimate suggested a potential clinical relevant improvement in the Symbol Digit Modalities Test (95% CI overlapping zero). Cardiorespiratory fitness increased in the total group and the cognitively impaired subgroup. Conclusion: In the present representative MS group, 24 weeks of supervised PAE had no effect on any cognitive domain in the total group but potentially improved processing speed in the cognitively impaired subgroup.