Cognitive Fatigability Interventions in Neurological Conditions: A Systematic Review

Fatigue management: a systematic review of objective measurement techniques for cognitive fatigue

BACKGROUND

Cognitive fatigue is a complex psychobiological state whereby task performance cannot be maintained. Return-to-work protocols typically rely on self-report measures, therefore the current systematic review aimed to identify "real-time" measures of objective cognitive fatigue to inform return-to-work protocols.

METHODS

Studies were included if participants were at least 18 years old, assessed "real-time" objective cognitive fatigue that could be used outside of the lab (neuroimaging measures were, therefore, excluded), used an induction task that was separate to the measurement, were adequately powered, compared objective cognitive fatigue at baseline and post-induction, and included a cognitive fatigue induction task that was at least 30 minutes long.Nine electronic databases were searched until 31 December 2022 (MEDLINE; PsychArticle; PubMED, ProQuest; ProQuest for gray literature; Google Scholar; The Cochrane Library; The Health Technology Assessment Database; and Web of Science), with alerts set up on Google Scholar to notify of new relevant research since this date (reviewed until December 2023). The checklist for quasi-experimental studies (Joanna Briggs Institute, 2014) was used to assess the risk of bias. Whilst a meta-analysis was planned, the data were unsuitable so only a narrative synthesis was conducted.

RESULTS

Fifty-seven studies were included, which were conducted within a variety of settings including naturalistic work scenarios, driving, aviation, and artificial computer-based tasks.Whilst the review found a range of potential measurements, there were inconsistencies in findings across studies highlighting the need for more research into the reliable measurement of objective cognitive fatigue in natural settings.

DISCUSSION

The findings suggest that eye- and body-related measures may be sensitive measures of objective cognitive fatigue. However, comparisons across measurement types should be cautiously interpreted because eye-related and cognitive measures were far more common. The review highlighted the need for more consistent and transparent reporting across the field to advance our understanding of cognitive fatigue.

At-distance neurocognitive rehabilitation during COVID-19 pandemic: A first glance of patients' perspectives about the process and an online platform

Despite the use of digital communication technologies in neurocognitive rehabilitation has been widely used in face-to-face interventions, the difficulties of using ICT-based tools to provide rehabilitation services and the unfamiliarity of the neuropsychologists with internet interventions limited the use of these kinds of interventions in their clinical practices. The lockdown and mitigating measures associated with the COVID-19 pandemic, on the other hand, forced the use of at-distance and online interventions as a means to mitigate the impact of those measures on the mental health and rehabilitation processes of people with neurological disorders. Overall, little is known about the perspectives of patients with acquired neurological conditions about rehabilitation services delivered at distance. Therefore, the main goal of this study was to explore the perceptions that patients with neurological disorders have on at-distance online neurocognitive rehabilitation, namely during the COVID-19 pandemic. Sixteen patients with acquired neurological conditions attending an online neurocognitive rehabilitation program in a Portuguese rehabilitation center filled in an online questionnaire during the mandatory lockdown. The results of this study highlight the potential of delivering rehabilitation services at distance, presenting its advantages and limitations from patients' perspectives, as well as suggestions for improving both neurorehabilitation processes and the online rehabilitation platform used.

[XVI Post-ECTRIMS Meeting: review of the new developments presented at the 2023 ECTRIMS Congress (II)]

The XVI Post-ECTRIMS meeting was held in Seville on 20 and 21 October 2023, where expert neurologists in multiple sclerosis (MS) summarised the main new developments presented at the ECTRIMS 2023 congress, which took place in Milan from 11 to 13 October. The aim of this article is to summarise the content presented at the Post-ECTRIMS Meeting, in an article in two parts. This second part covers the health of women and elderly MS patients, new trends in the treatment of cognitive impairment, focusing particularly on meditation, neuroeducation and cognitive rehabilitation, and introduces the concept of fatigability, which has been used to a limited extent in MS. The key role of digitalization and artificial intelligence in the theoretically near future is subject to debate, along with the potential these technologies can offer. The most recent research on the various treatment algorithms and their efficacy and safety in the management of the disease is reviewed. Finally, the most relevant data for cladribine and evobrutinib are presented, as well as future therapeutic strategies currently being investigated.

Fatigue and cognitive fatigability in patients with chronic pain

OBJECTIVES

Fatigue is common in patients with chronic pain. Still, there is a lack of studies examining objectively measurable cognitive aspects of fatigue: cognitive fatigability (CF). We aimed to investigate the presence of CF in patients with chronic pain and its relation to self-rated fatigue, attention, pain characteristics, sleep disturbance, depression, and anxiety.

METHODS

Two hundred patients with chronic pain and a reference group of 36 healthy subjects underwent a comprehensive neuropsychological test battery, including measurement of CF with the Wechsler Adult Intelligence Scale-III Coding subtest, and self-assessment of trait and state fatigue.

RESULTS

The patients with chronic pain did not show more CF as compared to the reference group. There was an association between CF and processing speed on a test of sustained and selective attention in the chronic pain group, while self-rated fatigue measures and pain characteristics were not associated with CF. Self-rated fatigue measures were highly correlated with self-rated pain intensity, spreading of pain, depression, anxiety, and sleep disturbance.

CONCLUSIONS

The findings highlight the distinction between objective and subjective aspects of fatigue in chronic pain, and that the underlying causes of these different aspects of fatigue need to be studied further.

Investigating cognitive reserve, symptom resolution and brain connectivity in mild traumatic brain injury

BACKGROUND

A proportion of patients with mild traumatic brain injury (mTBI) suffer long-term consequences, and the reasons behind this are still poorly understood. One factor that may affect outcomes is cognitive reserve, which is the brain's ability to maintain cognitive function despite injury. It is often assessed through educational level or premorbid IQ tests. This study aimed to explore whether there were differences in post-concussion symptoms and symptom resolution between patients with mTBI and minor orthopedic injuries one week and three months after injury. Additional aims were to explore the relationship between cognitive reserve and outcome, as well as functional connectivity according to resting state functional magnetic resonance imaging (rs-fMRI).

METHOD

Fifteen patients with mTBI and 15 controls with minor orthopedic injuries were recruited from the emergency department. Assessments, including Rivermead Post-Concussion Questionnaire (RPQ), neuropsychological testing, and rs-fMRI scans, were conducted on average 7 days (SD = 2) and 122 days (SD = 51) after injury.

RESULTS

At the first time point, significantly higher rates of post-concussion symptoms (U = 40.0, p = 0.003), state fatigue (U = 56.5, p = 0.014), and fatigability (U = 58.5, p = 0.025) were observed among the mTBI group than among the controls. However, after three months, only the difference in post-concussion symptoms remained significant (U = 27.0, p = 0.003). Improvement in post-concussion symptoms was found to be significantly correlated with cognitive reserve, but only in the mTBI group (Spearman's rho = -0.579, p = .038). Differences in the trajectory of recovery were also observed for fatigability between the two groups (U = 36.5, p = 0.015). Moreover, functional connectivity differences in the frontoparietal network were observed between the groups, and for mTBI patients, functional connectivity differences in an executive control network were observed over time.

CONCLUSION

The findings of this pilot study suggest that mTBI, compared to minor orthopedic trauma, is associated to both functional connectivity changes in the brain and concussion-related symptoms. While there is improvement in these symptoms over time, a small subgroup with lower cognitive reserve appears to experience more persistent and possibly worsening symptoms over time. This, however, needs to be validated in larger studies.

TRIAL REGISTRATION

NCT05593172. Retrospectively registered.

Cognition and Cognitive Fatigability: Association with Employment Status in Multiple Sclerosis

BACKGROUND

Slowed processing speed impacts employment status in people with multiple sclerosis (PwMS). Studies on the Multiple Sclerosis Functional Composite (MSFC), which includes the Paced Auditory Serial Addition Test (PASAT), have demonstrated that the combined score predicts employment status. Whether PASAT performance alone is associated with employment status is less clear. In addition, no studies have yet evaluated whether cognitive fatigability (CF), as measured with the PASAT, is associated with employment status. The aim of the current study was to examine the association between PASAT performance, CF, and employment status in PwMS.

METHODS

Hundred and eighty-six PwMS completed the PASAT as part of a larger neuropsychological battery. ANOVAs and chi-squares analyzed group differences between employed and unemployed participants with respect to demographics, PASAT performance scores, and CF. Linear regression determined whether PASAT performance and/or CF scores were associated with employment status.

RESULTS

After controlling for demographic influences, group differences were noted between employed vs. unemployed individuals on PASAT performance scores only. Employment status was associated with PASAT performance scores but not CF.

CONCLUSIONS

The current study confirmed that PASAT performance is associated with employment status in MS. Given that CF was not associated, it seems difficulties with information processing speed (IPS) and working memory have more impact on a PwMS's ability to remain employed rather than within-task performance decline.

Cognitive and mental fatigue in chronic pain: cognitive functions, emotional aspects, biomarkers and neuronal correlates-protocol for a descriptive cross-sectional study

INTRODUCTION

Chronic pain (CP) is one of the most frequently presenting conditions in health care and many patients with CP report mental fatigue and a decline in cognitive functioning. However, the underlying mechanisms are still unknown.

METHODS AND ANALYSIS

This study protocol describes a cross-sectional study aimed at investigating the presence of self-rated mental fatigue, objectively measured cognitive fatigability and executive functions and their relation to other cognitive functions, inflammatory biomarkers and brain connectivity in patients with CP. We will control for pain-related factors such as pain intensity and secondary factors such as sleep disturbances and psychological well-being. Two hundred patients 18-50 years with CP will be recruited for a neuropsychological investigation at two outpatient study centres in Sweden. The patients are compared with 36 healthy controls. Of these, 36 patients and 36 controls will undergo blood sampling for inflammatory markers, and of these, 24 female patients and 22 female controls, between 18 and 45 years, will undergo an functional MRI investigation. Primary outcomes are cognitive fatigability, executive inhibition, imaging and inflammatory markers. Secondary outcomes include self-rated fatigue, verbal fluency and working memory. The study provides an approach to study fatigue and cognitive functions in CP with objective measurements and may demonstrate new models of fatigue and cognition in CP.

ETHICS AND DISSEMINATION

The study has been approved by the Swedish Ethics Review Board (Dnr 2018/424-31; 2018/1235-32; 2018/2395-32; 2019-66148; 2022-02838-02). All patients gave written informed consent to participate in the study. The study findings will be disseminated through publications in journals within the fields of pain, neuropsychology and rehabilitation. Results will be spread at relevant national and international conferences, meetings and expert forums. The results will be shared with user organisations and their members as well as relevant policymakers.

TRIAL REGISTRATION NUMBER

NCT05452915.

Development of a behavioural intervention for cognitive fatigability in multiple sclerosis: Protocol for a pilot and feasibility study

Background

Up to 90% of people with multiple sclerosis (PwMS) subjectively report fatigue as one of their worst symptoms. Fatigability is an objectively measured component of fatigue. Cognitive fatigability (CF) is a breakdown in task performance following sustained cognitive effort. There is a paucity of interventions targeting CF in MS. The prior success of behavioural interventions at improving subjective fatigue suggests that their adaptation may yield similar results for CF. Given the relationship between CF, sleep quality, and mood, a behavioural intervention targeting these factors, such as cognitive behavioural therapy (CBT), is warranted. Given the multidimensional nature of fatigue, a multifaceted approach targeting lifestyle factors and coping (e.g., fatigue management education supplemented by CBT for insomnia and exercise) might prove efficacious.

Aim

We describe a protocol for a pilot feasibility study to design and implement a multi-dimensional behavioural intervention to improve CF in PwMS.

Methods

Stage 1: development of a multi-dimensional group-based videoconference-delivered behavioural intervention based on a previously successful fatigue management program for PwMS. A facilitator manual will be drafted. Course material will focus on four themes: body (sleep and physical activity), mood (impact of depression and anxiety), mind (cognitive contributions), and context (pacing and communication). Stage 2: a needs assessment survey will be completed by 100 PwMS for input on what factors are important contributors to their CF. Modifications will be made to the course material and manual. Stage 3: the facilitator-delivered intervention will include 20 PwMS. After baseline assessment, participants will attend weekly 70-min videoconference group sessions for 8 weeks, including homework assignments. Follow-up assessment will re-evaluate outcomes. Stage 4: analysis and dissemination of results. The primary outcome is improvement in CF. Additional feasibility outcomes will determine if a randomized control trial (RCT) is pursued. Stage 5: refine the intervention based on outcomes and feedback from participants. Determining which aspects participants felt were most effective will help inform RCT design.

Conclusion

The long-term goal is to ensure that PwMS have access to effective interventions in real-world settings to improve quality of life and enhance their ability to participate in cognitively demanding activities that they enjoy.

[Tiredness, fatigue and exhaustion: all the same or manifestations of a continuum?-Food for thought]

Owing to the COVID-19 pandemic and the associated post-COVID syndrome, the concept "fatigue" has gained significant importance. However, both the definition and the causes of fatigue differ depending on the disease pattern in question. Moreover, individuals who describe their symptoms in everyday clinical settings seem almost universally to use the terms tiredness, fatigue and exhaustion synonymously. In 2007, Olson described these three terms as being distinct states in her view, but that they can be placed in relation to each other on a continuum. Taking up this consideration, an overview of current research is provided. For this purpose, the published literature of the last 2 years was searched for the terms "tiredness", "fatigue" and "exhaustion". Some common diagnostic instruments can be found. However, the great variety of instruments used to capture the three terms is striking. Despite these different diagnostic and definition possibilities, different therapeutic measures can be derived for each of the three symptoms. It is crucial, especially with regard to further therapy, to separate the three terms tiredness, fatigue and exhaustion from each other and to consider each of them separately on the common continuum. This is the only way to establish both an accurate diagnosis and the successful individual therapy that goes along with it.

Cognitive fatigability assessment test (cFAST): Development of a new instrument to assess cognitive fatigability and pilot study on its association to perceived fatigue in multiple sclerosis

Background

Fatigue is a common symptom of many diseases, including multiple sclerosis. It manifests as a cognitive or physical condition. Fatigue is poorly understood, and effective therapies are missing. Furthermore, there is a lack of methods to measure fatigue objectively. Fatigability, the measurable decline in performance during a task, has been suggested as a complementary method to quantify fatigue.

Objective

To develop a new and objective measurement of cognitive fatigability and investigate its association with perceived fatigue.

Methods

We introduced the cognitive fatigability assessment test (cFAST), a novel smartphone-based test to quantify cognitive fatigability. Forty-two people with multiple sclerosis (23 fatigued and 19 non-fatigued, defined by the Fatigue Scale for Motor and Cognitive Functions) took part in our validation study. Patients completed cFAST twice. We used t-tests, Monte Carlo sampling, and area under the receiver operating characteristic curves to evaluate our approach using two sets of proposed metrics.

Results

When classifying fatigue, our fatigability metric Δresponse time has a mean area under the receiver operating characteristic curve of 0.74 (95% CI 0.64–0.84), making it the best performing metric for this task. Furthermore, Δresponse time shows a statistically significant difference between the fatigued and non-fatigued groups (t = 2.27, P = .03). Particularly, cognitively-fatigued patients decline in performance, while non-fatigued patients do not.

Conclusions

We introduce cFAST, a new instrument to quantify cognitive fatigability. Our pilot study provides evidence that cognitive fatigability assessment test produces a quantifiable drop in cognitive performance in a short period. Furthermore, our results indicate that cFAST may have the potential to serve as a surrogate for subjective cognitive fatigue. cFAST is significantly shorter than the existing fatigability assessments and does not require specialized equipment. Thus, it could enable frequent and remote monitoring, which could substantially aid clinicians in better understanding and treating fatigue.

Sex-specific disruption in corticospinal excitability and hemispheric (a)symmetry in multiple sclerosis

Multiple Sclerosis (MS) is a neurodegenerative disease in which pathophysiology and symptom progression presents differently between the sexes. In a cohort of people with MS (n = 110), we used transcranial magnetic stimulation (TMS) to investigate sex differences in corticospinal excitability (CSE) and sex-specific relationships between CSE and cognitive function. Although demographics and disease characteristics did not differ between sexes, males were more likely to have cognitive impairment as measured by the Montreal Cognitive Assessment (MoCA); 53.3% compared to females at 26.3%. Greater CSE asymmetry was noted in females compared to males. Females demonstrated higher active motor thresholds and longer silent periods in the hemisphere corresponding to the weaker hand which was more typical of hand dominance patterns in healthy individuals. Males, but not females, exhibited asymmetry of nerve conduction latency (delayed MEP latency in the hemisphere corresponding to the weaker hand). In males, there was also a relationship between delayed onset of ipsilateral silent period (measured in the hemisphere corresponding to the weaker hand) and MoCA, suggestive of cross-callosal disruption. Our findings support that a sex-specific disruption in CSE exists in MS, pointing to interhemispheric disruption as a potential biomarker of cognitive impairment and target for neuromodulating therapies.

Validation of Discrete and Regression-Based Performance and Cognitive Fatigability Normative Data for the Paced Auditory Serial Addition Test in Multiple Sclerosis

Cognitive fatigability is an objective performance decrement that occurs over time during a task requiring sustained cognitive effort. Although cognitive fatigability is a common and debilitating symptom in multiple sclerosis (MS), there is currently no standard for its quantification. The objective of this study was to validate the Paced Auditory Serial Addition Test (PASAT) discrete and regression-based normative data for quantifying performance and cognitive fatigability in an Ontario-based sample of individuals with MS. Healthy controls and individuals with MS completed the 3″ and 2″ versions of the PASAT. PASAT performance was measured with total correct, dyad, and percent dyad scores. Cognitive fatigability scores were calculated by comparing performance on the first half (or third) of the task to the last half (or third). The results revealed that the 3″ PASAT was sufficient to detect impaired performance and cognitive fatigability in individuals with MS given the increased difficulty of the 2″ version. In addition, using halves or thirds for calculating cognitive fatigability scores were equally effective methods for detecting impairment. Finally, both the discrete and regression-based norms classified a similar proportion of individuals with MS as having impaired performance and cognitive fatigability. These newly validated discrete and regression-based PASAT norms provide a new tool for clinicians to document statistically significant cognitive fatigability in their patients.

A Proposal for a Unifying Set of Definitions of Fatigue

In this paper, we propose a set of unifying definitions that are useful in all areas of fatigue research while remaining neutral to the various theories about fatigue. We first set up two criteria and four desiderata that a definition for interdisciplinary use needs to fulfill: (i) non-circularity, (ii) finiteness, (iii) broadness, (iv) precision, (v) neutrality, and (vi) phenomenon-focus. We argue that other existing attempts to unify definitions within fatigue research do not fulfill all of these criteria and desiderata. Instead, we argue for a set of stipulative definitions, centered around performance measures and subjective estimations, is required in order to maximize clarity. In total, a set of 13 distinct definitions of fatigue and fatigue-related phenomena is presented. These definitions will help facilitate communication between different researchers, link phenomena from divergent research fields together, facilitate application and knowledge production, and increase the specificity for hypothesis testing.

Cognitive fatigue interventions for people with multiple sclerosis: A scoping review

BACKGROUND

Fatigue is a common symptom experienced by people with multiple sclerosis (MS) and can be categorized as physical or cognitive fatigue. The existing body of literature mostly focuses on physical fatigue in MS and there is limited research on cognitive fatigue and interventions to effectively manage cognitive fatigue in this cohort. Therefore, the aim of this scoping review is to identify and summarize available research literature about different types of interventions to manage cognitive fatigue to provide a comprehensive perspective on treatment options.

METHODS

The PRISMA Extension for Scoping Reviews methodology was used. Searches were conducted in May 2021 in the following databases: CINAHL Plus with Full Text, MEDLINE via Ovid, PsycINFO, Embase via Ovid, and ProQuest Dissertations and Theses Global. The inclusion criteria were: peer-reviewed journal articles written in English or French that included an intervention to manage MS cognitive fatigue. Search keywords included multiple sclerosis, cognitive fatigue, and intervention. All retrieved citations' titles and abstracts were screened, and eligible articles were fully reviewed by two reviewers. The included studies were categorized based on the type of intervention, and effect size were calculated to estimate the effectiveness of the interventions.

RESULTS

Of 653 retrieved citations, 34 were retained for this review. Participants of the included studies were mostly middle-aged adults with relapsing-remitting MS, without severe mobility issues, who were living with MS for about 10 years on average. The majority of studies were randomized controlled trials (n = 17), followed by pilot and feasibility trials (n = 4), case-control (n = 2), and other experimental designs (n = 11). The interventions were categorized as educational programs (such as self-management programs, diet, and counselling) (n = 18), medical and pharmacological (such as monoaminergic stabilizers, natalizumab, and dalfampridine) (n = 6), and exercise and physical interventions (such as resistance training, aquatic exercise, and walking) (n = 10). Of the included interventions, fatigue self-management interventions that incorporate educational materials and involve trained facilitators seem to be optimal for reducing the negative effects of cognitive fatigue.

CONCLUSION

This review identified a variety of interventions for MS cognitive fatigue management. However, there is not sufficient evidence leading to a clear recommendation about appropriate and effective approaches for cognitive fatigue management. More research in this field is needed.

Methylphenidate may improve mental fatigue in individuals with multiple sclerosis: A pilot clinical trial

BACKGROUND

Fatigue is the most common symptom in multiple sclerosis (MS), previously attributed to dopamine imbalance. Evidence suggests that methylphenidate, a psychostimulant that increases striatal and prefrontal dopamine levels, is effective in reducing fatigue in various disorders. However, its effect on state vs. trait mental fatigue in MS is yet to be examined.

METHODS

This pilot study investigates the efficacy of methylphenidate on decreasing self-reported mental fatigue in 12 individuals with MS in a double-blind, placebo-controlled, cross-over randomized clinical trial.

RESULTS

Our results show that "state", but not "trait" MS-related fatigue, was reduced after 4 weeks of methylphenidate administration as compared to placebo.

Does Intensive Training of Attention Influence Cognitive Fatigability in Patients With Acquired Brain Injury?

Research Objectives

Impairments in attention and the speed of information processing are central to the experience of cognitive fatigue in patients with acquired brain injury (ABI). Attention may be improved through intensive training in a rehabilitation setting. The aim of the study was to investigate the feasibility of reducing cognitive fatigability (CF) using attention training and to explore the effect of two different approaches to attention training.

Design

Randomised controlled study in a rehabilitation setting.

Participants

59 patients (age 19-59 years) with mild to moderate stroke or traumatic brain injury in the early (<4 month) phase.

Interventions

Patients were randomly assigned to intensive specific training with Attention Process Training (APT) or Activity-Based Attention Training (ABAT) for 3-5 days per week for a period of 5-6 weeks with a total of 20 h, in addition to traditional interdisciplinary rehabilitation.

Main Outcome Measure

CF was conceptualised as performance decline in terms of an increased number of incorrect responses between the first and the last quintiles of the Paced Auditory Serial Addition Test (PASAT). A negative result was defined as fatigability. The evaluator of fatigability was blinded to treatment.

Results

At baseline, there were no differences between the groups in age, education, reasoning, anxiety or depression. After training, a significant treatment effect was found (p = 0.020), as the APT-group, but not the ABAT-group, had improved. However, after controlling for baseline differences regarding CF on the PASAT-f, the difference was no longer significant.

Conclusion

The results indicate that cognitive training might be a feasible method for reducing CF through attention training and that patients with high levels of CF benefit most from attention training. The type of intervention provided, whether specific or activity-based attention training, appears to be of less importance, as there was no treatment effect after controlling for the baseline level of CF. Future studies are required to confirm the validity of the findings.

Cognitive Fatigability is Independent of Subjective Cognitive Fatigue and Mood in Multiple Sclerosis

BACKGROUND

Sustained cognitive testing is used to detect cognitive fatigability and is often considered a substitute for subjective cognitive fatigue (CF). However, the relationship between cognitive fatigability and subjective CF in people with multiple sclerosis (PwMS) remains undetermined.

OBJECTIVE

To explore potential associations between fatigability induced by sustained cognitive testing and subjective CF in PwMS.

METHODS

We gave 120 PwMS and 60 demographically matched, healthy individuals the Beck Depression Inventory-FastScreen (BDI-FS) to measure mood and the Modified Fatigue Impact Scale to measure CF. In addition, we used the Quotient ADHD Test, a sustained attention test, to measure cognitive fatigability. We also explored potential correlations between the individuals' performance on the sustained attention test and thalamic volume using recent MRI scans.

RESULTS

Forty-one (34.2%) of the PwMS exhibited cognitive fatigability. These 41 were found to be significantly older (P=0.006), had been diagnosed with the disease for longer (P=0.03), had higher scores (P<0.001) on the Expanded Disability Status Scale, and had reduced thalamic volume (P=0.04) compared with the 79 (65.8%) PwMS not exhibiting cognitive fatigability. The PwMS exhibiting cognitive fatigability scored similarly on the BDI-FS (P=0.21) and self-reported similar rates of CF (P=0.62) as the PwMS not exhibiting cognitive fatigability.

CONCLUSION

Cognitive fatigability induced by sustained cognitive testing is not an accurate clinical alternative to subjective CF. This study provides evidence to support cognitive fatigability and CF in PwMS as two distinct concepts.

Walking and cognitive performance in adults with multiple sclerosis: Do age and fatigability matter?

BACKGROUND

Co-occurring walking and cognitive performance deficits are debilitating consequences of multiple sclerosis (MS) that worsen with age. However, it is unknown if fatigability influences such age-related worsening of walking and cognitive performance.

OBJECTIVE

This cross-sectional study examined possible age-related differences in walking-related motor fatigability (incremental six-minute-walk (6MW) performance) and cognitive fatigability (incremental Symbol Digit Modalities Test (SDMT) performance) in adults with MS.

METHODS

196 adults with MS were categorized into age-groups: younger (20-39 years; n = 53), middle-aged (40-59 years; n = 89), and older (60-79 years; n = 54), and completed the 6MW and SDMT. Age-group differences in incremental 6MW and SDMT performance, controlling for disability status, were examined using separate, mixed-factor ANCOVAs.

RESULTS

There were no statistically significant age-group-by-time interactions on walking-related motor or cognitive fatigability when controlling for disability. However, there were significant main effects of time on incremental 6MW (p = 0.01) and SDMT (p < 0.01) performance indicating the presence of walking-related motor and cognitive fatigability, respectively, collapsed across age-groups.

CONCLUSION

Fatigability does not exert a primary influence on age-related worsening of walking and cognitive neuroperformance outcomes among adults with MS. This suggests that walking-related motor fatigability and cognitive fatigability may not be optimal targets for mitigating age-related declines in ambulation and cognition among adults with MS.