Do baseline cognitive status, participant specific characteristics and EDSS impact changes of cognitive performance following aerobic exercise intervention in multiple sclerosis?

PURPOSE

Cognitive impairment is a common symptom of multiple sclerosis (MS). Physical exercise represents a promising non-pharmacological therapy option, however, potential predictors for successful cognitive improvements mediated by exercise remain to be elucidated in order to optimize targeted exercise training regimens. One of the most promising exercise training regime in this context is high-intensity interval training (HIIT). Against this backdrop, this study i) analysed the effects of a three-week HIIT compared to moderate continuous exercise on cognitive performance and ii) investigated potential predictors for changes of cognitive performance following a three-week aerobic exercise intervention.

METHODS

Datasets of two randomized controlled trials (RCT) were pooled, resulting in a total sample size of n = 130 persons with MS (pwMS) who either performed HIIT or moderate intensity continuous (MCT) exercise 3-5x/ week for three weeks. Cognitive performance was assessed with the Brief International Cognitive Assessment for MS. I) Potential within (time) and interaction (time x group) effects for cognitive performance were investigated with univariate analyses of covariance (ANCOVA). II) Potential predictors for changes of cognitive performance were assessed by multiple linear regression models.

RESULTS

ANCOVA revealed significant time effects for all cognitive outcomes and a time x group interaction for verbal learning (p=.045), with HIIT inducing superior effects compared to moderate continuous exercise (MCT). Cognitive status (impaired/intact cognition) (p= .008) and exercise regime (HIIT/moderate continuous) (p=.040) influenced changes of verbal learning. Cognitive status (p=.006) and EDSS (p=.048) affected changes of visuospatial memory in pwMS. The models accounted for 5.4% and 7.7% of the variance.

CONCLUSION

Cognitive status, exercise regime and EDSS potentially impact changes of specific cognitive domains following aerobic exercise. Further predictors for changes of cognitive performance following an aerobic exercise intervention need to be investigated as current results accounted only for a limited amount of variance. RCTs that investigate effects of physical exercise on cognitive performance should include only pwMS with impaired baseline cognitive performance. To better understand the impact of exercise on cognitive performance, it is furthermore recommendable to include cognitive assessments in clinical routine.