Cognitive Impairment Impacts Exercise Effects on Cognition in Multiple Sclerosis

Abstract

Purpose: Exercise training reveals high potential to beneficially impact cognitive performance in persons with multiple sclerosis (pwMS). Research indicates that high-intensity interval training (HIIT) has potentially higher effects on physical fitness and cognition compared to moderate continuous exercise. This study (i) compares the effects of a 3-week HIIT and moderate continuous exercise training on cognitive performance and cardiorespiratory fitness of pwMS in an overall analysis and (ii) investigates potential effects based on baseline cognitive status in a subgroup analysis. Methods: Seventy-five pwMS were randomly assigned to an intervention (HIIT: 5 × 1.5-min intervals at 95-100% HRmax, 3 ×/week) or active control group (CG: 24 min continuous exercise at 65% HRmax, 3 ×/week). Cognitive performance was assessed pre- and post-intervention with the Brief International Cognitive Assessment for MS (BICAMS). (I) To examine potential within (time) and interaction (time × group) effects in the overall analysis, separate analyses of covariance (ANCOVA) were conducted. (II) For the subgroup analysis, participants were divided into two groups [intact cognition or impaired cognition (>1.5 standard deviation (SD) compared to healthy, age-matched norm data in at least one of the three tests of the BICAMS]. Potential impacts of cognitive status and intervention were investigated with multivariate analyses of variance (MANOVA). Results: Overall analysis revealed significant time effects for processing speed, verbal learning, rel. VO2peak, and rel. power output. A time*group interaction effect was observed for rel. power output. Subgroup analysis indicated a significant main effect for cognition (impaired cognition vs. intact cognition). Subsequent post-hoc analysis showed significant larger effects on verbal learning in pwMS with impaired cognition. Conclusion: Current results need to be confirmed in a powered randomized controlled trial with cognitive performance as primary endpoint and eligibility based on cognitive performance that is assessed prior to study inclusion.

Keywords: cognitive performance; exercise; high-intensity exercise; processing speed; verbal learning; visuospatial memory.

Conflict of interest statement

DL discloses research grants/consultancy/speaker bureau from Novartis, Merck, TEVA, Biogen, Sanofi, Bayer. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Copyright © 2021 Rademacher, Joisten, Proschinger, Bloch, Gonzenbach, Kool, Langdon, Bansi and Zimmer.

Figures

Figure 1

Participant flow diagram.

Figure 2

Baseline-adjusted ANCOVA results for physical fitness outcomes (A, B) and fatigue (C) for the intervention (HIIT) and control group (CG). T0, baseline; T1, post-intervention; FSMC, fatigue scale for motor and cognitive functions; rel., relative. Deviation bars are shown as standard error.

Figure 3

Baseline-adjusted ANCOVA results for cognitive performance parameters for the intervention (HIIT) and control group (CG). T0, baseline; T1, post-intervention. (A) SDMT, Symbol Digit Modalities Test; (B) VLMT, Verbal Learning Memory Test; (C) BVMT-R, Brief Visuospatial Memory Test-Revised. Deviation bars are shown as standard error.

Figure 4

Changes of cognitive performance parameters based on baseline cognition for the intervention (HIIT) and control group (CG). (A) SDMT, Symbol Digit Modalities Test; (B) VLMT, Verbal Learning Memory Test; (C) BVMT-R, Brief Visuospatial Memory Test-Revised. Deviation bars are shown as standard error. *Significant changes between groups of cognitive status.