Is there a threshold or dose-response association between physical activity and cognitive function in multiple sclerosis?

Abstract

Objective: Cognitive impairment is prevalent, disabling, and poorly managed in multiple sclerosis (MS). Physical activity, often expressed as steps/day, has been associated with cognitive function in this population. This brief report examined the possibility of a (1) steps/day threshold associated with absence of cognitive impairment or (2) dose-response relationship between steps/day and cognitive function in MS.

Method: The sample included 358 persons with MS who provided demographic (age, sex, race) and clinical (MS type, disease duration, disability status) information, and completed the Symbol Digit Modalities Test (SDMT) and California Verbal Learning Test-Second Edition (CVLT-II). Participants wore an ActiGraph GT3X+ accelerometer above the non-dominant hip during waking hours of the day over a 7-day period for measuring steps/day.

Results: The receiver operating characteristic (ROC) curve analysis did not identify a steps/day threshold associated with cognitive impairment on SDMT (area under the curve [AUC] ranged between 0.606 and 0.691). The ROC curve analysis further did not identify a threshold of steps/day associated with cognitive impairment based on CVLT-II (AUC range 0.606 to 0.691). The regression analysis indicated significant linear relationships between steps/day and SDMT (R² = .06; β=.251; p < .001) and CVLT-II (R² = .06; β=.247; p < .001) z-scores.

Conclusion: The observed linear relationship suggests that focusing on increasing steps/day across all levels of physical activity might have benefits for cognitive function in MS.