Aerobic fitness is associated with inhibitory control in persons with multiple sclerosis

Impact of physical activity, physical fitness and exercises on cognitive impairment in patients with multiple sclerosis: A review of evidence and underlying mechanisms

Cognitive impairment in persons with MS (pwMS) occurs commonly, early and independently of other clinical features of the disease. MS-related cognitive impairment is mainly characterized by weakening of information processing speed, working memory and episodic memory. Much evidence, based on both neuropsychological and neuroimaging outcomes, highlights successful cognitive rehabilitation interventions. In this context, promotion of physical activity and exercise training could be a dual, motor and cognitive, rehabilitation method. The aim of this article is, firstly, to review existing evidence regarding the effects of exercise on cognition among pwMS, and secondly, to explore the possible mechanisms of action of the cognitive-motor coupling.

Size or Strength? how components of muscle relate to behavioral and neuroelectric measures of executive function independent of aerobic fitness

While previous research has linked cognitive function with resistance exercise, the nuanced links between muscle strength, mass, and neuroelectric function are less understood. Therefore, this study investigated the association of muscle strength and mass with inhibitory control (IC), working memory (WM), and related neuroelectric activity. A total of 123 18-50-year-old adults completed maximal aerobic capacity and strength tests, a body composition scan, and IC and WM tasks while the N2 and P3 components of event-related potentials were recorded. Bivariate correlations revealed aerobic fitness, strength, and mass were associated with behavioral and neuroelectric outcomes. After accounting for age, sex, and aerobic fitness, strength was associated with intra-individual response time variability, accuracy, and P3 latency during WM. Muscle mass was associated with N2 latency during IC. While relationships with behavioral outcomes did not persist after controlling for the opposite muscle outcome, greater strength and mass were related to shorter P3 latency during WM and shorter N2 latency during IC, respectively. These results provide initial evidence that muscle outcomes are associated with executive function and neuroelectric processing speed, suggesting distinct contributions of strength and mass to cognition. This work highlights the significance of maintaining muscle strength and mass alongside aerobic fitness for optimal cognitive health.

Application of an Adaptive, Digital, Game-Based Approach for Cognitive Assessment in Multiple Sclerosis: Observational Study

Background

Cognitive impairment is one of the most debilitating manifestations of multiple sclerosis. Currently, the assessment of cognition relies on a time-consuming and extensive neuropsychological examination, which is only available in some centers.

Objective

To enable simpler, more accessible cognitive screening, we sought to determine the feasibility and potential assessment sensitivity of an unsupervised, adaptive, video game–based digital therapeutic to assess cognition in multiple sclerosis.

Methods

A total of 100 people with multiple sclerosis (33 with cognitive impairment and 67 without cognitive impairment) and 24 adults without multiple sclerosis were tested with the tablet game (EVO Monitor) and standard measures, including the Brief International Cognitive Assessment for Multiple Sclerosis (which included the Symbol Digit Modalities Test [SDMT]) and Multiple Sclerosis Functional Composite 4 (which included the Timed 25-Foot Walk test). Patients with multiple sclerosis also underwent neurological evaluations and contributed recent structural magnetic resonance imaging scans. Group differences in EVO Monitor performance and the association between EVO Monitor performance and standard measures were investigated.

Results

Participants with multiple sclerosis and cognitive impairment showed worse performance in EVO Monitor compared with participants without multiple sclerosis (P=.01) and participants with multiple sclerosis without cognitive impairment (all P<.002). Regression analyses indicated that participants with a lower SDMT score showed lower performance in EVO Monitor (r=0.52, P<.001). Further exploratory analyses revealed associations between performance in EVO Monitor and walking speed (r=–0.45, P<.001) as well as brain volumetric data (left thalamic volume: r=0.47, P<.001; right thalamic volume: r=0.39, P=.002; left rostral middle frontal volume: r=0.28, P=.03; right rostral middle frontal volume: r=0.27, P=.03).

Conclusions

These findings suggest that EVO Monitor, an unsupervised, video game–based digital program integrated with adaptive mechanics, is a clinically valuable approach to measuring cognitive performance in patients with multiple sclerosis.

Trial Registration

ClinicalTrials.gov NCT03569618; https://clinicaltrials.gov/ct2/show/NCT03569618

Protocol for a systematically-developed, phase I/II, single-blind randomized controlled trial of treadmill walking exercise training effects on cognition and brain function in persons with multiple sclerosis

Slowed cognitive processing speed (CPS) is a common and debilitating consequence of multiple sclerosis (MS) that is notoriously difficult to treat. As such, we undertook a systematic line of research that indicated that supervised, progressive treadmill walking exercise (TMWX) training might improve CPS and brain functioning among fully-ambulatory persons with MS. The current study will be the first adequately-powered, single-blind randomized controlled trial (RCT) that examines the efficacy of 12-weeks of TMWX training compared with an active control condition on CPS, thalamocortical brain connectivity (based on resting-state fMRI), and exploratory functional outcomes in 88 fully-ambulatory persons with MS who present with slowed CPS. The intervention condition involves supervised, progressive TMWX training 3 times/week over 12-weeks; this initially involves 15-min of light-to-moderate intensity TMWX that progresses up to 40-min of vigorous intensity TMWX. The active control condition involves supervised, minimal intensity, stretching-and-resistance exercise that will be delivered on the same frequency as the intervention condition. The primary study outcomes involve Symbol Digit Modalities Test performance (i.e., CPS) and fMRI-based measures of thalamocortical resting-state functional connectivity. Exploratory study outcomes involve measures of community participation, activities of daily living, quality of life, and functional mobility. All study outcomes will be administered before and after the 12-week study period by treatment-blinded assessors. If successful, the current study will provide the first Class I evidence for the effects of TMWX training as an approach for improving CPS and its neural correlate, and possibly mitigating the impact of slowed CPS on functional outcomes in MS.

Will behavioral treatments for cognitive impairment in multiple sclerosis become standards-of-care?

Cognitive impairment is common and debilitating in persons with multiple sclerosis (MS), and further is poorly-managed by pharmacotherapy. Cognitive rehabilitation and exercise training have been identified as promising behavioral approaches for managing MS-related cognitive impairment based on systematic reviews and meta-analyses. However, each body of literature is associated with similar sets of methodological shortcomings, as has been identified by periodic systematic reviews and meta-analyses. Thus, there is little generalizability or transportability research supporting either behavioral approach for managing cognitive dysfunction in this population under real-world conditions (i.e., as a standard-of-care). To that end, this paper aims to catalyze the advancement of cognitive rehabilitation and exercise training research in MS, respectively, towards the successful implementation of generalizability/transportability trials. This first involves critical examinations of the respective cognitive rehabilitation and exercise training literatures in MS from a chronological perspective, with particular emphasis on how the fields have each evolved in response to systematic reviews and meta-analyses. Accordingly, the current paper then provides a roadmap for harmonizing research in those areas to systematically and efficiently inform the development of generalizability/transportability trials for behavioral approaches to manage MS-related cognitive dysfunction. This involves the recognition of overlapping facilitators and impediments for progress in each field, including considerations for the implementation of neuroimaging. Ultimately, the provision of such a framework aims to shorten the timeline for research to influence clinical practice and improve the lives of cognitively-impaired persons with MS.

Characterization of inhibitory failure in Multiple Sclerosis: Evidence of impaired conflict resolution

INTRODUCTION

Inhibitory control deficits are frequently reported in Multiple Sclerosis (MS), although it is unclear whether these deficits represent a global or process-specific failure. Notably, most models of inhibitory control recognize at least two dissociable processes, the most consistent being: (a) the inhibition of a dominant response: response suppression, and (b) the inhibition of a dominant response and initiation of a nondominant response: executive control. This study aimed to ascertain the processes underlying inhibitory failure in MS.

METHOD

Twenty-three MS patients and 25 healthy controls completed a battery of commonly used inhibitory tasks, with measures from each task entered into a principal components analysis with orthogonal (varimax) rotation.

RESULTS

As anticipated, two components emerged, with tasks evaluating response suppression (stop signal, go/no go) loading on a common component, and tasks evaluating executive control (Stroop, antisaccade, endogenously-cued saccade) loading on a separate common component. Composite scores were generated for each component and compared between groups. Unlike response suppression scores, executive control scores were significantly poorer for MS patients.

CONCLUSIONS

Inhibitory control deficits in MS may reflect poor resolution in the context of competing processes, rather than difficulty in preventing the execution of an inappropriate response.

Aerobic Capacity Is Not Associated with Most Cognitive Domains in Patients with Multiple Sclerosis-A Cross-Sectional Investigation

(1) Background: Cognitive impairment is highly prevalent in multiple sclerosis (MS). Staying physically fit may be associated with preservation of cognitive performance in persons with MS (pwMS); (2) Objective: To investigate the association between aerobic capacity and the cognitive domains of information processing, learning and memory, and verbal fluency as well as single and composite z-scores of the Brief Repeatable Battery of Neuropsychological tests (BRBNT) in pwMS; (3) Methods: All subjects first performed the BRBNT and then a maximal oxygen consumption (VO₂-max) test on a bicycle ergometer as a measure of aerobic capacity. Simple and multiple (adjusting for age, sex, and education level) regression analyses were performed to evaluate the relationship between aerobic capacity and cognitive performance in different domains. Published international norms were used to compute z-scores for each individual and composite BRBNT score. Furthermore, cognitive impairment was defined as one or more z-scores ≤−1.5 standard deviation (SD) of healthy controls; (4) Results: Eighty-four subjects were included (44.9 ± 9 years, 16.3 ± 2 education years, Expanded Disability Status Scale (EDSS): 2.6 ± 1.4, MS-type (relapsing-remitting, primary progressive, or secondary progressive): 73/6/5, disease duration: 9.9 ± 7 years, VO₂-max: 28.4 ± 7.0 mL O₂/min/kg). No significant associations between aerobic capacity and cognitive performance in the individual BRBNT tests were found, except that a weak relationship was found between aerobic capacity and the composite processing speed z-score (R² = 0.06, p = 0.02). The average global BRBNT z-score (−0.2 ± 0.66) was not associated with aerobic capacity. Comparison of the cognitively impaired group (34.5%) with the nonimpaired group (65.5%) showed lower aerobic capacity in the impaired group (25.9 ± 1 vs. 29.7 ± 1 mLO₂/min/kg, p = 0.02); (5) Conclusions: Limited support was found for an association between performance in most cognitive domains and aerobic capacity in the present MS group with a third of patients showing signs of cognitive impairments.

Exercise as a Countermeasure to Declining Central Nervous System Function in Multiple Sclerosis

PURPOSE

The decline of central nervous system (CNS) function is a hallmark characteristic of multiple sclerosis (MS) that can manifest as cognitive impairment. We believe that exercise represents a potential behavioral approach for counteracting the declines in CNS structure and associated function among persons with MS (ie, exercise as a countermeasure of CNS decline). This theory is important because disease-modifying drugs represent a first-line approach for modifying the immune system and its effects on the CNS, but these drugs do not generally demonstrate robust improvements in cognitive performance.

METHODS

To the best of our knowledge, this article presents the first argument positioning exercise as a countermeasure for CNS decline in MS.

FINDING

The reviewed research indicates a proliferating body of evidence describing physical fitness, physical activity, and exercise effects on cognitive performance and neuroimaging outcomes (ie, CNS functioning) in MS, with the consistent and strong association between cognitive performance and neuroimaging outcomes in this population as a backdrop.

IMPLICATIONS

We further present a framework and future research directions for better positioning exercise as a possible neuroprotective behavior against declining CNS function in MS.

Systematic, Evidence-Based Review of Exercise, Physical Activity, and Physical Fitness Effects on Cognition in Persons with Multiple Sclerosis

Cognitive dysfunction is highly prevalent, disabling, and poorly-managed in persons with multiple sclerosis (MS). Recent evidence suggests that exercise might have beneficial effects on cognition in this population. The current systematic, evidence-based review examined the existing literature on exercise, physical activity, and physical fitness effects on cognition in MS to accurately describe the current status of the field, offer recommendations for clinicians, and identify study-specific and participant-specific characteristics for providing future direction for ongoing MS research. We performed an open-dated search of Medline, PsychInfo, and CINAHL in December 2015. The search strategy involved using the terms 'exercise' OR 'physical activity' OR 'physical fitness' OR 'aerobic' OR 'resistance' OR 'balance' OR 'walking' OR 'yoga' OR 'training' OR 'rehabilitation' AND 'multiple sclerosis'. Articles were eliminated from the systematic review if it was a review article, theoretical paper, or textbook chapter; did not involve persons with MS; involved only persons with pediatric-onset MS; did not involve neuropsychological outcomes; did not include empirical data to evaluate outcomes; involved pharmacological interventions; or was not available in English. The selected articles were first classified as examining exercise, physical activity, or physical fitness, and were then randomly assigned to 2 independent reviewers who rated each article for level of evidence based on American Academy of Neurology criteria. Reviewers further completed a table to characterize important elements of each study (i.e., intervention characteristics), the cognitive domain(s) that were targeted, participant-specific characteristics, outcome measures, and study results. The present review resulted in 26 studies on the effects of exercise, physical activity, and physical fitness on cognition in persons with MS. This included 1 Class I study, 3 Class II studies, 8 Class III studies, and 14 Class IV studies. Of the 26 total studies, 6 were randomized controlled trials. Overall, there is conflicting evidence for the effects of exercise on cognition in MS, and overall positive, but not definitive evidence for the effects of physical activity and physical fitness, respectively, on cognition in this population. Collectively, there is insufficient well-designed research to definitively conclude that exercise, physical activity, and physical fitness are effective for improving cognition in MS. This is based, in part, on methodological issues of Class I and II studies, such as inclusion of cognition as a secondary outcome (35 % of reviewed studies), poorly-developed exercise interventions, and paucity of research that included cognitively-impaired MS samples. However, promising evidence from Class III and Class IV studies may be useful for informing the development of better intervention research.

Effects of vigorous walking exercise on core body temperature and inhibitory control in thermosensitive persons with multiple sclerosis

Aim: Acute, moderate intensity aerobic exercise might improve cognition in multiple sclerosis (MS), but it is unknown if increases in core body temperature (Ctemp) that negates those effects in thermosensitive persons with MS. Materials & methods: Fourteen fully ambulatory, thermosensitive persons with MS completed 20-min bouts of vigorous intensity treadmill walking exercise and seated quiet rest in a randomized, counterbalanced order. Ctemp was measured throughout each experimental condition. Inhibitory control (i.e., an executive function) was measured immediately prior to and following each condition. Results: Ctemp was elevated (˜0.6°C) with vigorous exercise versus quiet rest (p < 0.05). There further were pre-to-post improvements in inhibitory control for vigorous exercise versus quiet rest (ηp 2 = 0.29). Conclusion: Exercise-related increases in Ctemp do not nullify the potential acute exercise benefits on inhibitory control in MS.

Exercise and cognition in multiple sclerosis: The importance of acute exercise for developing better interventions

Cognitive dysfunction is highly prevalent, disabling, and poorly-managed in persons with multiple sclerosis (MS). Exercise training represents a promising approach for managing this clinical symptom of the disease. However, results from early randomized controlled trials of exercise on cognition in MS are equivocal, perhaps due to methodological concerns. This underscores the importance of considering the well-established literature in the general population that documents robust, beneficial effects of exercise training on cognition across the lifespan. The development of such successful interventions is based on examinations of fitness, physical activity, and acute exercise effects on cognition. Applying such an evidence-based approach in MS serves as a way of better informing exercise training interventions for improving cognition in this population. To that end, this paper provides a focused, updated review on the evidence describing exercise effects on cognition in MS, and develops a rationale and framework for examining acute exercise on cognitive outcomes in this population. This will provide keen insight for better developing exercise interventions for managing cognitive impairment in MS.