Free-living ambulatory physical activity and cognitive function in multiple sclerosis: the significance of step rate vs. step volume.

Background: Physical activity (PA) represents a promising behavioral approach for managing cognitive dysfunction in multiple sclerosis (MS). However, there is a lack of information on the pattern of free-living PA intensity (e.g., step rate) and its unique association with cognition. Such information is essential for informing clinical trials in MS.

Objective: We examined associations among PA volume and intensity with cognitive function in persons with MS, and intensity was derived from steps-based metrics (peak 30-min cadence [Peak-30], and time spent in incremental cadence bands).

Methods: We included data from 147 persons with MS who underwent assessments of cognitive function (via Brief International Cognitive Assessment in MS) and wore an ActiGraph GT3X + accelerometer for 7 days. We performed bivariate and partial correlations and regression analyses examining associations among PA metrics and cognitive outcomes.

Results: Higher Peak-30 was significantly associated with better performance in cognitive processing speed and verbal learning and memory (r = 0.19-0.38), and the associations remained significant when controlling for daily steps, age, sex, and years of education (p < 0.05). By comparison, daily steps was only correlated with cognitive processing speed (r = 0.26), and the association was non-significant when controlling for Peak-30 and covariates. There were stronger correlations among time spent in higher intensity cadence bands with cognitive performance (r = 0.18-0.38).

Conclusion: Our results highlight the important role of PA intensity for cognition in MS, and may inform future development of focal PA interventions that focusing on step rate patterns for improving cognition in persons with MS.