The Influence of Cognitive Impairment on the Fitness/Cognition Relationship in Multiple Sclerosis
Objectives: The current cross-sectional investigation examined whether cardiorespiratory fitness was differentially associated with processing speed in persons with MS with and without PSI.
Methods: 64 persons with MS undertook the Symbol Digit Modalities Test (SDMT) for establishing groups with and without MS-related PSI, a modified flanker task for measuring processing speed performance, and an incremental exercise test to exhaustion on a cycle ergometer for measuring cardiorespiratory fitness in a single testing session. Bivariate correlations were performed on cardiorespiratory fitness and processing speed outcomes in PSI group subsamples.
Results: Cardiorespiratory fitness was not significantly associated with processing speed (ρ=−.20, p=.08) in the sample without PSI. However, in the sample with PSI, cardiorespiratory fitness was significantly associated with processing speed (ρ=−.62, p=.01), such that lower cardiorespiratory fitness was strongly associated with slower processing speed.
Conclusions: This study provides preliminary evidence of a significant association between cardiorespiratory fitness and processing speed in persons with MS-related PSI. Such an investigation provides the first direct support for aerobic exercise training as a possible behavioral approach for managing/treating MS-related cognitive impairment, beyond merely improving cognitive performance.