Device-Measured Physical Activity and Cognitive Processing Speed Impairment in a Large Sample of Persons with Multiple Sclerosis

Abstract

Objective: There is accumulating evidence regarding the beneficial effects of physical activity (PA) on cognitive processing speed in persons with multiple sclerosis (MS). However, one overarching limitation of this research is that researchers have not recruited samples who have the actual problem of being studied (i.e., cognitive processing speed impairment). This study examined associations between device-measured PA and cognitive processing speed in a large sample of persons with MS overall and between those with and without cognitive processing speed impairment. Method: Three hundred eighty-five persons with MS underwent the oral Symbol Digit Modalities Test (SDMT) and wore an accelerometer for 7 days for PA measurement. We divided the overall sample into subsamples with (n = 140) and without (n = 245) cognitive processing speed impairment based on age, sex, and education-adjusted SDMT Z-scores. Results: After controlling for age and disability status, higher levels of device-measured PA were significantly associated with faster cognitive processing speed overall, and the association was significantly stronger among persons with MS who presented with cognitive processing speed impairment. Conclusions: This examination provides initial cross-sectional support for informing the development of PA interventions as a possible approach for managing MS-related cognitive processing speed impairment. This highlights the importance of developing purposefully designed trials involving PA interventions for targeting cognitive processing speed as a primary end point among persons with MS with impaired cognitive processing speed.

Cardiorespiratory fitness and free-living physical activity are not associated with cognition in persons with progressive multiple sclerosis: Baseline analyses from the CogEx study

“…That hypothesis was based on previous evidence reporting stronger associations among cardiorespiratory fitness, physical activity, and cognition in cognitively-impaired compared with non-cognitively impaired persons with predominantly relapsing-remitting MS and mild-to-moderate disability. [11,13] The current pattern of results was consistent with other research describing disability status as a moderator of the cardiorespiratory fitness/cognition relationship in MS, whereby the relationship was not statistically significant in persons with moderate-to-severe MS disability (EDSS ≥4.0). [10] This suggests that perhaps ambulatory disability status has a stronger influence on the fitness/cognition relationship than cognitive status in this population.…”

“…Although screening for progressive MS, physical inactivity, and low SDMT scores is advantageous for the design of the CogEx RCT [7,14] (i.e., pre-screening participants for the problem being studied), this effectively restricted the range of scores on the baseline outcomes, increasing the likelihood of smaller, cross-sectional correlations. [33] By extension, given previous reports of statistically significant correlations among cardiorespiratory fitness, physical activity, and cognition in primarily relapsing-remitting MS samples, [10][11][12][13] perhaps larger baseline correlations may have been observed if physical inactivity and CPS impairment were not inclusion criteria. Although baseline cardiorespiratory fitness and free-living MVPA were not associated with cognitive performance, the current cross-sectional results have important implications for the consideration of aerobic exercise training as an approach for managing progressive MS-related cognitive impairment.…”

“…The current study involved a cross-sectional analysis of associations among measures of cardiorespiratory fitness, free-living moderate-to-vigorous physical activity (MVPA), and cognitive performance in a large, international sample of persons with progressive MS who presented with objective CPS impairment from the multi-site CogEx RCT [14]. Based on previous evidence of particularly strong associations among cardiorespiratory fitness, free-living physical activity, and cognitive performance in cognitively-impaired persons with MS, [11,13] the overall hypothesis was that higher cardiorespiratory fitness and levels of free-living MVPA would similarly be associated with better cognitive performance.…”

“…8 By comparison, we are aware of only one study reporting on aerobic exercise training-related cognitive benefits in progressive MS. That pilot randomized controlled trial (RCT) reported that 8-10 weeks of aerobic cycle ergometer exercise training was associated with improvements in cardiorespiratory fitness, verbal memory, and alertness in a small sample of persons with progressive MS. 9 One approach for informing the development of future aerobic exercise training interventions for improving cognition involves examining associations among cardiorespiratory fitness, physical activity (as cross-sectional surrogates for components of aerobic exercise), and cognition in this population. There is evidence describing significant associations between cardiorespiratory fitness and cognition, [10][11][12] and physical activity and cognition, 13 respectively, in non-progressive MS samples. Several recent studies have reported particularly strong correlations in cognitively impaired MS samples; 11,13 that early-stage evidence has directly informed the development of ongoing RCTs.…”

“…There is evidence describing significant associations between cardiorespiratory fitness and cognition, [10][11][12] and physical activity and cognition, 13 respectively, in non-progressive MS samples. Several recent studies have reported particularly strong correlations in cognitively impaired MS samples; 11,13 that early-stage evidence has directly informed the development of ongoing RCTs. 6 Such results support the possibility of strong associations among cardiorespiratory fitness, physical activity, and cognition in progressive MS cohorts, and further might allow for head-to-head comparisons of cardiorespiratory fitness and physical activity as correlates of cognitive performance in this population.…”