Mood shapes the impact of reward on perceived fatigue from listening

Knowledge of the underlying mechanisms of effortful listening could help to reduce cases of social withdrawal and mitigate fatigue, especially in older adults. However, the relationship between transient effort and longer term fatigue is likely to be more complex than originally thought. Here, we manipulated the presence/absence of monetary reward to examine the role of motivation and mood state in governing changes in perceived effort and fatigue from listening. In an online study, 185 participants were randomly assigned to either a "reward" (n = 91) or "no-reward" (n = 94) group and completed a dichotic listening task along with a series of questionnaires assessing changes over time in perceived effort, mood, and fatigue. Effort ratings were higher overall in the reward group, yet fatigue ratings in that group showed a shallower linear increase over time. Mediation analysis revealed an indirect effect of reward on fatigue ratings via perceived mood state; reward induced a more positive mood state which was associated with reduced fatigue. These results suggest that: (1) listening conditions rated as more "effortful" may be less fatiguing if the effort is deemed worthwhile, and (2) alterations to one's mood state represent a potential mechanism by which fatigue may be elicited during unrewarding listening situations.

Microstructural analysis of verbal fluency performance in relapsing-remitting multiple sclerosis based on the impact of disability level

Verbal fluency (VF) evaluates language and cognitive abilities. This study compared VF in Relapsing-Remitting Multiple Sclerosis (RRMS) and healthy controls (HC), examining variables including correct responses (CR), mean cluster size (MCS), switches (S), and fluency difference score (FDS). RRMS participants were subgrouped by Expanded Disability Status Scale (EDSS), to explore the relationship between MS severity and VF. Twenty-four RRMS participants and matched HCs underwent Mini-Mental State Exam and VF Test. Statistical analysis compared VF between RRMS subgroups based on severity levels, and in HC. RRMS significantly impacted the CR, and S (CRSF p = 0.01, SSF p = 0.002; CRPF=0.002, SPF p = 0.002), while there was no significant difference in FDS between RRMS groups (p = 0.9). No significant relationship was found between EDSS scores, and VF subtests (CRSF p = 0.061, MCSSF p = 0.46, SSF p = 0.051, CRPF p = 0.521, MCSPF p = 0.966, SPF p = 0.599). In RRMS, our results demonstrate impairments in all VF parameters except the MCSSF+PF, and FDS. This study suggests that intact MCSSF+PF may reflect preserved verbal memory and word recall, while significant switching differences may indicate impaired cognitive flexibility. Similar FDS to those of HC suggest that no performance discrepancy in subtests in RRMS. Intact MCS might be a distinctive pattern in the early clinical stage of MS.

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.

The Relationship between Diurnal Measures of Tonic Alertness and Self-Reported Fatigue in Persons with Multiple Sclerosis-A Retrospective Data Analysis

OBJECTIVE

Fatigue in multiple sclerosis (MS) is common, burdensome, and usually assessed by self-report measures. This retrospective data analysis of the twice-daily Alertness test (Test battery of Attentional Performance) examined the extent to which this assessment procedure is associated with MS-related fatigue.

METHOD

Two-hundred and thirteen German inpatients (136 women) aged 18-69 years with predominantly relapsing MS (72.8%) were included. Based on reaction time (RT) differences between morning tonic alertness (8:30-11:00 a.m.) and afternoon tonic alertness (3:00-4:30 p.m.), patients were divided into an "improver," "maintainer," or "decliner" group. Multinomial logistic regression (MLR) was calculated to predict the likelihood of belonging to one of these performance groups, taking into account cognitive fatigue (Fatigue Scale of Motor and Cognition, FSMCcog), disease severity (Expanded Disability Status Scale, EDSS), depression (Center for Epidemiologic Studies Depression Scale, CES-D), gender, and tonic alertness (a.m.).

RESULTS

The final MLR model (R2 = .30) included tonic alertness (a.m.) (<.001), FSMCcog (.008), EDSS (.038), CES-D (.161), and gender (.057). Using this model, correct assignment to alertness performance groups was 56.8%. Tonic alertness (p.m.) demonstrated the greatest potential for differentiation among the three performance groups (<.001).

CONCLUSIONS

These results show a relationship between subjective fatigue and tonic alertness. However, other variables also contribute to this association, suggesting that the RT differences between twice-daily measures of tonic alertness is not related to increased subjective fatigue in a substantial number of pwMS, which diminishes the diagnostic value. Further studies including relevant variables such as sleepiness are urgently needed.

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.

Slowing processing speed is associated with cognitive fatigue in newly diagnosed multiple sclerosis patients

OBJECTIVE

To further investigate objective measures of cognitive fatigue (CF), defined as the inability to sustain performance over time, in newly diagnosed multiple sclerosis (MS) patients, by conducting a performance analysis on the Paced Auditory Serial Addition Test (PASAT) based on the type of errors (omissions vs. incorrect responses) committed.

METHOD

Sixty-two newly diagnosed patients with MS (pwMS) and 41 healthy controls (HC) completed the PASAT. Analysis of the change in performance during the test was performed by comparing the number of correct responses, incorrect responses, and omissions in the 1^st versus the 3^rd tertile of the PASAT.

RESULTS

A significant decline in accuracy over time was observed to be related to an increment in the number of omissions, significantly more pronounced in pwMS than in HC. No change in the number of incorrect responses throughout the PASAT was observed for either group.

CONCLUSIONS

CF can be detected even in newly diagnosed pwMS and might objectively manifest as a progressive increase in omissions during a sustained highly demanding task (i.e., PASAT). This pattern may reflect slowed processing speed and increased fatigue in pwMS. Focusing on omissions on the PASAT instead of correct responses only may improve its specificity as an objective measure of CF.

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.

Reappraising cognitive reappraisal: The taxing impact of emotion regulation on executive functioning in older adults

OBJECTIVE

Cognitive reappraisal (CR) and expressive suppression (ES) are two common emotion regulation strategies that share similar cognitive and neural underpinnings. Prior research has consistently shown that recent engagement in ES (both self-reported and experimentally manipulated) is associated with subsequent temporary decrements in executive functioning (EF). Thus far, only one study has examined the association between CR and EF, with null results. However, that study was limited by examining only zero-order correlations and by assessing only the speed, not accuracy, of EF performance. The present study examined multivariate relationships among recent CR, recent ES, and EF (both speed and accuracy), as well as the potential impacts of more chronic engagements in, and trait-level preferences between, the two emotion regulation strategies.

METHOD

Participants were 201 community-dwelling older adults aged 60 to 93 who had participated in three separate studies examining the relationship between self-reported emotion regulation and EF.

RESULTS

Recent CR was associated with EF performance accuracy above and beyond chronic CR. Both recent CR and ES contributed to EF performance accuracy uniquely beyond each other and beyond chronic and preferred emotion regulation.

CONCLUSIONS

Both recent ES and CR appear to have a deleterious impact on EF performance accuracy, potentially due to utilization of similar resources; both should be accounted for when assessing emotion regulation and its impacts on EF.

Perceived Fatigue Impact and Cognitive Variability in Multiple Sclerosis

OBJECTIVE

People with Multiple Sclerosis (PwMS) and healthy controls (HCs) were evaluated on cognitive variability indices and we examined the relationship between fatigue and cognitive variability between these groups. Intraindividual variability (IIV) on a neuropsychological test battery was hypothesized to mediate the group differences expected in fatigue.

METHOD

Fifty-nine PwMS and 51 HCs completed a psychosocial interview and battery of neuropsychological tests and questionnaires during a 1-day visit. Fatigue in this study was measured with the Fatigue Impact Scale (FIS), a self-report multidimensional measure of fatigue. IIV was operationalized using two different measures, a maximum discrepancy score (MDS) and intraindividual standard deviation (ISD), in two cognitive domains, memory and attention/processing speed. Two mediation analyses with group (PwMS or HCs) as the independent variable, variability composite (memory or attention/processing speed) measures as the mediators, total residual fatigue (after accounting for age) as the outcome, and depression as a covariate were conducted. The Baron and Kenny approach to testing mediation and the PROCESS macro for testing the strength of the indirect effect were used.

RESULTS

Results of a mediation analysis using 5000 bootstrap samples indicated that IIV in domains of both attention/processing speed and memory significantly mediated the effect of patient status on total residual fatigue.

CONCLUSION

IIV is an objective performance measure that is related to differences in fatigue impact between PwMS and HCs. PwMS experience more variability across tests of attention/processing speed and memory and this experience of variable performance may increase the impact of fatigue.

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.

Listening-Related Fatigue in Children With Hearing Loss: Perspectives of Children, Parents, and School Professionals

PURPOSE

Children with hearing loss (CHL) are considered at risk for listening-related fatigue and its negative consequences. We collected data via focus groups and interviews from three stakeholder groups-CHL, their parents, and teachers/school professionals-in order to define the construct of listening-related fatigue from the perspective of CHL and key stakeholders. This is an important first step in our long-term goal to construct and validate a measure (i.e., scale) of listening-related fatigue for the pediatric population, with a focus on CHL. This article provides an overview of the data gathering process, analysis of qualitative reports, and the development of a theoretical framework for understanding the experience of listening-related fatigue in CHL.

METHOD

We conducted focus groups and interviews in school-age children exhibiting bilateral, moderate-to-profound hearing loss (n = 43), their parents (n = 17), and school professionals who work with CHL (n = 28). The discussions were audio-recorded, transcribed, and coded using a hierarchical coding system. Qualitative analysis was conducted using an iterative inductive-deductive approach.

RESULTS

We identified primary themes from the focus group/interview discussions to develop a theoretical framework of listening-related fatigue in CHL. The framework demonstrates the complex interaction among situational determinants that impact fatigue, symptoms or manifestations of fatigue, and the utilization of, and barriers to, coping strategies to reduce listening-related fatigue.

CONCLUSIONS

Participant discussion suggests that listening-related fatigue is a significant problem for many, but not all, CHL. Qualitative data obtained from these stakeholder groups help define the construct and provide a framework for better understanding listening-related fatigue in children.

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.

Predictors of cognitive fatigue and fatigability in multiple sclerosis

BACKGROUND

Persons with multiple sclerosis (PwMS) commonly experience cognitive fatigue (CF), defined as a decrease in cognitive performance with sustained activity, yet CF remains understudied. Further, the relationship between subjective CF and objective CF, or cognitive fatiguability, has not been fully elucidated in previous studies. Understanding the predictors of cognitive fatigue may scaffold the development of interventions that target this symptom. The objective of this prospective study was to evaluate the extent to which depression, anxiety, information processing speed, and sleep quality predict subjective and objective CF.

METHODS

PwMS were recruited from one academic MS clinic in London (ON) Canada. Objective CF was measured by the Paced Auditory Serial Addition Test (PASAT), where performance on the last third of the PASAT is compared to performance on the 1st third, a validated measurement of objective CF. Subjective CF was measured by the cognitive component of the Modified Fatigue Impact Scale (MFIS). Additionally, depression, anxiety, information processing speed, and sleep quality data was collected. All assessments took place on the same day. Pearson's r was calculated to examine the relationship among all continuous outcome measures while linear regression analyses were used to examine predictors of subjective and objective CF.

RESULTS

The sample consisted of 53 subjects who were mostly female (37; 69.8%) with a mean age of 44.2 years; the majority (47; 88.7%) had relapsing MS. Objective CF and subjective CF were not significantly related (r = - 0.16). Further, there was no statistically significant predictors of objective CF noted. In contrast, subjective CF demonstrated a statistically significant relationship with the Symbol Digit Modalities Test (SDMT; r = - 0.29, p = .05), Hospital Anxiety and Depression Scale (HADS), depression subscale (r = 0.61, p < .001), HADS anxiety subscale (r = 0.54, p < .001), and sleep quality (r = 0.33, p = .02). Additionally, all variables predicted subjective CF, R²_adj = 0.384 [F (6, 40) = 5.783, p = .0002]. In particular, anxiety significantly predicted subjective CF when controlling for depression, information speed, and sleep quality.

CONCLUSION

This study demonstrated that subjective CF is significantly predicted by anxiety, and strongly influenced by information processing impairment and depression. Addressing underlying affective factors, such as anxiety or depression, may help alleviate perceived or subjective CF among PwMS, thus improving their function and quality of life. Further studies with a larger sample size or longitudinal follow up may help define predictors of objective CF.

Mental fatigue correlates with depression of task-related network and augmented DMN activity but spares the reward circuit

Long-lasting and demanding cognitive activity typically leads to mental fatigue (MF). Indirect evidence suggests that MF may be caused by altered motivational processes. Here, we hypothesized that if MF consists in an alteration of motivational states, brain functional changes induced by MF could specifically affect the brain motivation circuit. In order to test this hypothesis, we devised a functional neuroimaging protocol to detect altered brain activity in reward-related brain regions in relation to cognitively induced mental fatigue. Twenty-five healthy participants underwent a FATIGUE and a CONTROL session on different days. In the FATIGUE session, MF was induced by performing a demanding cognitive task (adapted Stroop task) during 90 min, whereas in the CONTROL session, participants were asked to read magazines for the same period of time. We measured the neural consequences of the MF induction during a working memory task (Missing Number task) while modulating extrinsic motivation with block-wise variations in monetary reward. We also tracked participants' momentary fatigue, anxiety state and intrinsic motivation prior to and following the MF inducement and measurement. Accuracy on the Missing Number Task was lower in the FATIGUE than in the CONTROL condition. Furthermore, subjective MF, but not its behavioral manifestations, was associated with hypoactivity of the task-evoked neural responses. Importantly, activity in regions modulated by reward showed no differences between FATIGUE and CONTROL sessions. In parallel, subjective MF correlated with increased on-task activity and resting-state functional connectivity in the default mode network. These results indicate that subjective mental fatigue is not associated with altered activity in the brain motivation circuit but rather with hypoactivity in task-specific brain regions as well as relative increases of activity and connectivity in the default mode network during and after the task.

The influence of nocebo information on fatigue and urge to stop: An experimental investigation

BACKGROUND AND OBJECTIVES

Fatigue is an adaptive state after prolonged effort and often goes hand in hand with changes in behavior and motivation, such as the urge to stop exerting further effort. However, fatigue may become chronic in nature, as seen in multiple psychiatric disorders and chronic diseases, thereby losing its adaptive function. The etiology of fatigue symptoms remains poorly understood. We aimed to investigate whether nocebo information about the fatigue inducing nature of a cognitive task may contribute to the experience of fatigue and the motivational urge to stop.

METHODS

Participants (N = 46) repeatedly rated currently experienced fatigue while engaging in cognitive effort (working memory task). Crucially, half of participants received nocebo instructions prior to this task, whereas the other half only received neutral information.

RESULTS

Over the entire sample, results showed an increase in fatigue and urge to stop as the task progressed. Crucially, participants in the nocebo condition reported a higher urge to stop throughout the task relative to participants in the neutral condition. No significant effects were found for fatigue. Interestingly however, after controlling for baseline differences between conditions in negative affect, there was a significant Condition*Task block interaction effect on fatigue.

LIMITATIONS

Limitations include the relatively short experimental protocol and the underrepresentation of male relative to female participants.

CONCLUSIONS

These findings suggest that heightened awareness among clinicians and therapists about potential nocebo effects in their communication is warranted.

Cognitive Fatigue Predicts Cognitive Failure in Multiple Sclerosis Patients and Healthy Controls: A Case-Control Study

OBJECTIVE

Fatigue and cognitive deficits are frequent symptoms of multiple sclerosis (MS). However, the exact nature of their co-occurrence is not fully understood. We sought to determine the impact of cognitive and physical fatigue on subjective cognitive deficits in MS patients and healthy controls.

METHODS

Self-reports of fatigue (FSMC), depression (CES-D), cognitive deficits (CFQ), and personality traits (NEO-FFI, ANPS) among 30 MS inpatients and 30 healthy controls were analyzed using hierarchical regression models. The frequency of cognitive mistakes was used as the dependent variable and the extent of cognitive and physical fatigue as the independent variable.

RESULTS

Cognitive fatigue was the only unique and significant predictor of cognitive mistakes in both groups, explaining 13.3% of additional variance in the MS group after correcting for age, mood, and physical fatigue. Physical fatigue had no significant impact on cognitive mistakes. While age had an impact on cognitive mistakes and depression in healthy controls, this association was not significant in MS patients. Depression was significantly correlated with cognitive mistakes and cognitive fatigue in MS patients.

CONCLUSIONS

The interplay of cognitive fatigue and subjective cognitive impairment can be generalized, with the exception of the variables of age and depression, which were shown to have differing impacts on cognitive mistakes in MS patients and healthy controls, respectively. Cognitive fatigue was linked to cognitive mistakes even after correcting for overlapping items in MS patients only. Future research should further investigate the link between cognitive fatigue and attention lapses in daily life by using various objective assessments.

Nonmemory Composite Embedded Performance Validity Formulas in Patients with Multiple Sclerosis

OBJECTIVE

Research regarding performance validity tests (PVTs) in patients with multiple sclerosis (MS) is scant, with recommended batteries for neuropsychological evaluations in this population lacking suggestions to include PVTs. Moreover, limited work has examined embedded PVTs in this population. As previous investigations indicated that nonmemory-based embedded PVTs provide clinical utility in other populations, this study sought to determine if a logistic regression-derived PVT formula can be identified from selected nonmemory variables in a sample of patients with MS.

METHOD

A total of 184 patients (M age = 48.45; 76.6% female) with MS were referred for neuropsychological assessment at a large, Midwestern academic medical center. Patients were placed into "credible" (n = 146) or "noncredible" (n = 38) groups according to performance on standalone PVT. Missing data were imputed with HOTDECK.

RESULTS

Classification statistics for a variety of embedded PVTs were examined, with none appearing psychometrically appropriate in isolation (areas under the curve [AUCs] = .48-.64). Four exponentiated equations were created via logistic regression. Six, five, and three predictor equations yielded acceptable discriminability (AUC = .71-.74) with modest sensitivity (.34-.39) while maintaining good specificity (≥.90). The two predictor equation appeared unacceptable (AUC = .67).

CONCLUSIONS

Results suggest that multivariate combinations of embedded PVTs may provide some clinical utility while minimizing test burden in determining performance validity in patients with MS. Nonetheless, the authors recommend routine inclusion of several PVTs and utilization of comprehensive clinical judgment to maximize signal detection of noncredible performance and avoid incorrect conclusions. Clinical implications, limitations, and avenues for future research are discussed.

The Effect of Hearing-Protection Devices on Auditory Situational Awareness and Listening Effort

OBJECTIVES

Hearing-protection devices (HPDs) are made available, and often are required, for industrial use as well as military training exercises and operational duties. However, these devices often are disliked, and consequently not worn, in part because they compromise situational awareness through reduced sound detection and localization performance as well as degraded speech intelligibility. In this study, we carried out a series of tests, involving normal-hearing subjects and multiple background-noise conditions, designed to evaluate the performance of four HPDs in terms of their modifications of auditory-detection thresholds, sound-localization accuracy, and speech intelligibility. In addition, we assessed their impact on listening effort to understand how the additional effort required to perceive and process auditory signals while wearing an HPD reduces available cognitive resources for other tasks.

DESIGN

Thirteen normal-hearing subjects participated in a protocol, which included auditory tasks designed to measure detection and localization performance, speech intelligibility, and cognitive load. Each participant repeated the battery of tests with unoccluded ears and four hearing protectors, two active (electronic) and two passive. The tasks were performed both in quiet and in background noise.

RESULTS

Our findings indicate that, in variable degrees, all of the tested HPDs induce performance degradation on most of the conducted tasks as compared to the open ear. Of particular note in this study is the finding of increased cognitive load or listening effort, as measured by visual reaction time, for some hearing protectors during a dual-task, which added working-memory demands to the speech-intelligibility task.

CONCLUSIONS

These results indicate that situational awareness can vary greatly across the spectrum of HPDs, and that listening effort is another aspect of performance that should be considered in future studies. The increased listening effort induced by hearing protectors may lead to earlier cognitive fatigue in noisy environments. Further study is required to characterize how auditory performance is limited by the combination of hearing impairment and the use of HPDs, and how the effects of such limitations can be linked to safe and effective use of hearing protection to maximize job performance.

Cognitive fatigability in multiple sclerosis: How does performance decline over time on the Paced Auditory Serial Addition Test?

BACKGROUND

Cognitive fatigability (CF) can be defined as an inability to maintain an optimal level of performance throughout a sustained cognitive task. It remains unclear, however, whether there is a specific moment during a cognitive task, such as the Paced Auditory Serial Addition Test (PASAT), when performance begins to break down. Thus, the present study aimed to evaluate how performance declines over time on the PASAT in people with multiple sclerosis (PwMS) compared to healthy controls.

METHODS

178 PwMS and 186 control participants were administered the 3" and 2" PASAT as part of a larger battery of neuropsychological tests. To examine how CF differed between the groups, repeated measures ANOVAs were used to evaluate the cumulative error rates made by each group throughout the task. In addition, how the error rate developed across the task on each trial was examined to evaluate in more detail the difference between groups with respect to how performance declined from the beginning to the end of the task. Lastly, exploratory two-way independent sample ANOVAs examined whether there was an influence of stimulus complexity (single vs. double-digit answers) on task performance.

RESULTS

Compared to healthy controls, PwMS produced a greater number of errors overall on the PASAT and demonstrated more vulnerability to CF than healthy controls, as reflected by a greater number of errors made towards the end of the task. This difference was more noticeable on the 3" PASAT, given the difficulty both groups experienced on the 2" form. On the 3" PASAT, by Trial 37, PwMS had made significantly more cumulative errors than controls, however the rate of error generation was largely consistent and linear from the beginning to the end. Some of the group differences observed may be partially attributable to stimulus complexity influencing task performance.

CONCLUSIONS

The 3" PASAT is more sensitive to group differences in CF and error generation than the 2" PASAT. With respect to CF, the greater vulnerability observed in the MS group is not due to a breakdown in performance or an increase in the rate of error generation at any specific point during the task; rather there is a linear decline in performance from the start. These results suggest that PwMS struggle to maintain optimal performance during sustained cognitive effort from the very beginning and demonstrate a steeper, but steady, rate of decline over time.

Increasing the Clinical Utility of the Paced Auditory Serial Addition Test: Normative Data for Standard, Dyad, and Cognitive Fatigability Scoring

BACKGROUND

No normative data currently exist that would allow clinicians to decide whether the degree of cognitive fatigability (CF) experienced in individuals with neurologic disease is greater than expected when compared with a healthy population.

OBJECTIVE

To establish discrete and regression-based normative data for CF as defined by an objective decrement in performance over the course of a cognitive task; namely, the Paced Auditory Serial Addition Test (PASAT). In addition, to develop discrete and regression-based normative data for PASAT performance scores-dyad and percent dyad-for which data do not currently exist.

METHOD

One hundred and seventy-eight healthy individuals completed the PASAT as part of a larger neuropsychological battery. PASAT performance scores including total correct responses, total dyads, and percent dyad were calculated. CF scores were calculated by comparing the individuals' performance on the first half (or third) of the test to their performance on the last half (or third) in order to capture any within-task performance decrements over time.

RESULTS

Both age- and education-based discrete normative data and demographically adjusted (sex, age, and education) regression-based formulas were established for the PASAT performance scores and the CF scores.

CONCLUSION

The development of these normative data will allow for greater interpretation of an individual's performance on the PASAT, beyond just the total correct score, through the use of dyad and percent dyad scores. With respect to CF, these data will allow clinicians to objectively quantify decrements in cognitive performance over time better in individuals with neurologic diseases.

Mental fatigue measurement using eye metrics: A systematic literature review

Mental fatigue measurement techniques utilize one or a combination of the cognitive, affective, and behavioral responses of the body. Eye-tracking and electrooculography, which are used to compute eye-based features, have gained momentum with increases in accuracy and robustness of the lightweight equipment emerging in the markets and can be used for objective and continuous assessment of mental fatigue. The main goal of this systematic review was to summarize the various eye-based features that have been used to measure mental fatigue and explore the relation of eye-based features to mental fatigue. The review process, following the preferred reporting items for systematic reviews and meta-analyses, used the electronic databases Web of Science, Scopus, ACM digital library, IEEE Xplore, and PubMed. Of the 1,385 retrieved documents, 34 studies met the inclusion criteria, resulting in 21 useful eye-based features. Categorizing these into eight groups revealed saccades as the most promising category, with saccade mean and peak velocity providing quick access to the cognitive states within 30 min of fatiguing activity. Complex brain networks involving sympathetic and parasympathetic nervous systems control the relation of mental fatigue to tonic pupil size and have the potential to indicate mental fatigue in controlled experimental conditions. Other categories, like blinks, are derived from the field of sleep research and should be used with caution. Several limitations emerged in the analysis, including varied experimental methods, use of dim lighting during the experiment (that could possibly also induce sleepiness), and use of unclear data analysis techniques, thereby complicating comparisons between studies.

Understanding Listening-Related Fatigue: Perspectives of Adults with Hearing Loss

OBJECTIVE

Adults with hearing loss (AHL) often report feeling fatigued after being in situations that require prolonged listening, an experience referred to as listening-related fatigue. We conducted focus groups to identify key domains and constructs of listening-related fatigue. Our goal was to create a theoretical framework for understanding listening-related fatigue that could guide the development of a reliable and valid assessment tool.

DESIGN

Eight focus group discussions were conducted using a moderator's guide. Discussions were recorded, transcribed, coded, and analysed to identify common themes related to listening-related fatigue. A hierarchical coding manual was developed iteratively as new themes and subcategories were identified during the analysis process.

STUDY SAMPLE

Forty-three adults (11 males; aged 20 to 77 years) with varying degrees of hearing loss participated in the focus groups. Participants included primarily hearing aid users (n = 34), hearing aid candidates (n = 6), and a small group of cochlear implant users (n = 3).

RESULTS

Qualitative analyses revealed the multidimensional nature of listening-related fatigue for AHL, including physical, mental, emotional, and social domains. These varied experiences were influenced by the external (acoustic/environmental) characteristics of the listening situation, the internal state of the listener (cognitive/motivational), and coping strategies implemented to modify the listening experience. The use of amplification had both positive and negative effects on listening-related fatigue.

CONCLUSIONS

For some AHL, the consequences of listening-related fatigue can be significant, negatively impacting their quality of life. Data from these focus groups provides a framework for understanding the experience of listening-related fatigue among AHL. This is a critical first step in the development of a tool for measuring listening-related fatigue in this at-risk group.

Chronic versus recent expressive suppression burdens are differentially associated with cognitive performance among older adults

Introduction: Expressive suppression (ES; suppression of affective behavior) has been shown to have a deleterious impact on subsequently administered tests of executive functions (EF), threatening validity, and reliability of EF assessment. Past research has shown that recent ES (i.e., across 24 hours prior to testing) and chronic ES (i.e., across 2 weeks prior to testing) have differential impact on test performance. The present study compared the association of chronic vs. recent ES with speed vs. accuracy of performance on tests of EF and tests of lower-order processes.

METHOD

Participants were 255 community-dwelling older adults aged 60 and older. Participants completed timed subtests of the Delis-Kaplan Executive Function System and the Burden of State Emotion Regulation Questionnaire.

RESULTS

Hierarchical linear regressions examined the contributions of chronic vs. recent ES to test performance. Recent ES was related to scores of both speed and accuracy on EF tests. The association between recent ES and EF errors held beyond covariates (i.e., chronic ES, demographics, depression, and general cognitive status). In contrast, the association between recent ES and EF speed was fully explained by EF error scores. Chronic ES was associated only with speed of performance and only on lower-order tasks, but this relationship did not survive correction for cognitive, psychiatric, and demographic factors.

CONCLUSIONS

Recent ES appears to be a risk factor for EF lapses. Chronic ES, while related to performance speed, seems to also relate to several other cognitive, psychiatric, and demographic factors, which themselves explain slower information processing.

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.

Neural mechanisms underlying state mental fatigue in multiple sclerosis: a pilot study

Neuroimaging underpinnings of state (in the moment, transient) mental fatigue in multiple sclerosis (MS) are not well understood. The current pilot study examined the effect of state mental fatigue on brain activation (measured using functional magnetic resonance imaging [fMRI]) during conditions of varying cognitive loads of rapid information processing in persons with MS relative to healthy controls. Nineteen persons with MS and 17 healthy controls underwent fMRI scanning while performing a modified version of the Symbol Digit Modalities Test, which consisted of high and low cognitive load conditions with comparable visual stimulation. State mental fatigue was assessed using the Visual Analog Scale of Fatigue before and after each run of the behavioral task. Results indicated that the healthy control group recruited significantly more anterior brain regions (superior and middle frontal gyri, insula, and superior temporal gyrus) to meet increased task demands during the high cognitive load condition as fatigue level increased (p < 0.05), which was accompanied by shorter response time. In contrast, the MS group did not recruit anterior areas to the same extent as the healthy control group as task demands and fatigue increased. Indeed, the MS group continued to activate more posterior brain regions (precuneus, lingual gyrus, and middle occipital gyrus) for the high cognitive load condition (p < 0.05) with no improvement in speed. In conclusion, persons with MS may allocate neural resources less efficiently than healthy controls when faced with increased task demands, which may result in increased mental fatigue. Results of the current pilot investigation warrant replication with a larger sample size.

Naming error in multiple sclerosis patients: A pilot study in Isfahan, Iran

Background:

Although cognitive impairment is common in multiple sclerosis (MS) patients, language difficulties are controversy and little information is available on nonEnglish languages. Therefore, the present cross-sectional study was conducted to assess the naming accuracy in Persian relapsing-remitting MS (RRMS) patients.

Materials and Methods:

Thirty RRMS patients were recruited from Kashani Comprehensive MS Center, Isfahan, Iran. Their performance on measures of mini mental state examination (MMSE), Expanded Disability Status Scale, and Naming Test was compared with control participants.

Results:

MS patients were found to have much more naming errors than the control group (2.1 ± 1.8 vs. 0.54 ± 1.1 P = 0.02). Average MMSE score of MS patients was 27.23 (range = 18–30, standard deviation [SD] = 2) versus 28.96 (range = 19–30, SD = 3.2) in controls.

Conclusion:

The present study suggests that naming ability can be impaired in RRMS regardless of disability score. Specific language function tests including naming should be considered in the process of evaluating and rehabilitating patients with MS.

Cognitive Fatigability Interventions in Neurological Conditions: A Systematic Review

INTRODUCTION

Although fatigue is a well-studied concept in neurological disease, cognitive fatigability (CF) is less understood. While most studies measure fatigue using subjective self-report, fewer have measured CF objectively. Given the negative impact of CF on quality-of-life, there is a need for targeted interventions. The objective of this review was to determine which procedural, behavioural and pharmacological treatments for objectively measured CF are available to people living with neurological conditions.

METHODS

In accordance with the PRISMA guidelines, systematic searches for randomized control trials (RCTs), case-controlled studies and case reports/series were conducted across the Ovid Medline, PsycInfo, EMBASE and Cochrane Library databases. English-language articles published between 1980 and February 2019 were considered for eligibility. Included were those that objectively measured CF in individuals with neurological disease/disorder/dysfunction between the ages of 18 and 65 years. Studies were reviewed using a modified Cochrane Data Extraction Template. Risk of bias was assessed using the Cochrane Risk of Bias tool. The review process was facilitated using Covidence software (www.covidence.org). Two authors reviewed articles independently, with a third resolving conflicts regarding article inclusion.

RESULTS

The search identified 450 records. After duplicates were removed and remaining titles/abstracts were screened for eligibility, 28 full-text articles were assessed, and two studies were included in the qualitative synthesis. Studies were a priori divided into those with pharmacological, procedural or behavioural interventions. Two studies met eligibility criteria; both of these included participants with multiple sclerosis. One study utilized a procedural intervention (i.e. transcranial direct current stimulation), while the other utilized a pharmacological intervention (i.e. fampridine-SR). Studies were evaluated for risk of bias, and evidence from both eligible studies was discussed.

CONCLUSION

Despite the positive results of the procedural intervention, the paucity of eligible studies and the nascent nature of the field suggests that more studies are required before firm conclusions can be drawn regarding the amenability of CF to treatment.

TRIAL REGISTRATION

The review was registered with PROSPERO (CRD42019118706).

An observational study of trait and state fatigue, and their relation to cognitive fatigability and saccade performance

Aim:

Different fatigue measurements and their relation to saccadic functions were investigated in 15 patients with a mild traumatic brain injury (mTBI) and 15 orthopedic controls.

Materials & methods:

State fatigue was measured with the Fatigue Severity Scale and trait fatigue with the question on fatigue in the Rivermead Post Concussion Questionnaire and fatigability as decreased performance over time on a neuropsychological measure.

Results:

Patients with an mTBI scored significantly higher in state fatigue and showed more fatigability compared with the orthopedic controls. Among patients with mTBI, state fatigue correlated with prosaccade latency and cognitive fatigability, while trait fatigue correlated with anxiety and antisaccade latency and variability.

Conclusion:

This pilot study indicates that saccade measurements might, in the future, be useful in the understanding of fatigue and in the search for prognostic factors after mTBI.

Imaging cognitive fatigability in multiple sclerosis: objective quantification of cerebral blood flow during a task of sustained attention using ASL perfusion fMRI

Cognitive fatigability (CF) can be defined as an inability to maintain performance throughout a sustained cognitive task. Individuals with multiple sclerosis (MS) are more susceptible to CF than healthy controls (HCs); however, the neural correlates underlying CF are still under investigation. Arterial spin labeling (ASL) perfusion imaging provides a non-invasive method of objectively quantifying cerebral blood flow (CBF) during sustained attention tasks. To date, no study has yet evaluated CF in MS using this methodology. 10 MS and 10 HCs completed a 20-min psychomotor vigilance task (PVT). CF was evaluated by dividing the PVT into quintiles and examining performance from the 1st to the last. Mean reaction times (RTs) and number of lapses were recorded. Global and regional CBF changes were evaluated throughout the PVT as well as during pre- and post-task rest. Increased susceptibility to CF was noted in the MS group. Distinct patterns of CBF activation were observed in areas comprising fronto-parietal, cortico-striatal, cerebellar, and basal ganglia regions; however, when and how these regions were engaged differed between the MS and HC groups. In particular, dysfunction in CBF to the middle frontal gyrus may underlie the CF effects observed. In addition, individuals with MS appear to struggle with "switching off" regions of the attentional network at rest following sustained cognitive effort. Findings support the use of ASL as an appropriate methodology for evaluating CF in MS with an overall pattern of attentional network dysfunction being observed. Objectively quantifying CF in this manner can help validate patients' subjective complaints.

Motivation in multiple sclerosis cognitive fatigue: An experimental approach

Introduction: Cognitive fatigue is a common symptom in multiple sclerosis (MS). Recent research has implicated dopaminergic pathways originating in the basal ganglia as neurological correlates of cognitive fatigue in MS. This same system has long been associated with goal-directed behavior and reward-based motivation. While researchers have demonstrated that reward has a reliable impact on performance in tasks of sustained attention in healthy individuals, the effect of reward on fatigue is less clear, as prior research has not adequately controlled for desensitization to reward in a sustained attention task. The primary aims of this study were to examine the effect of reward on attention in MS patients, and to examine the effect of reward on objective cognitive fatigue. Method: The study employed a 3 × 3 repeated measures design to evaluate performance of N = 64 patients with definite MS on a measure of cognitive fatigue across several reward conditions. The study utilized a novel delayed-reward paradigm to better control the measured effect of reward on fatigue. Results: Reward (main effect) displayed a significant effect on overall performance (F = 3.050, p < .05). Reward was also shown to affect fatigue trajectory (Reward × Interval, F = 2.433, p < .05). However, this effect was dependent on the method of reward administration. Conclusions: Study findings support the role of motivation in MS cognitive performance, particularly in objective cognitive fatigue, a behavioral finding that is consistent with current neuropsychological theory. Study findings support the delayed-reward paradigm as an effective method for measuring reward effect on tasks of sustained attention.

Cognitive Fatigue in Multiple Sclerosis: An Objective Approach to Diagnosis and Treatment by Transcranial Electrical Stimulation

Cognitive fatigue is one of the most frequent symptoms in multiple sclerosis (MS), associated with significant impairment in daily functioning and quality of life. Despite its clinical significance, progress in understanding and treating fatigue is still limited. This limitation is already caused by an inconsistent and heterogeneous terminology and assessment of fatigue. In this review, we integrate previous literature on fatigue and propose a unified schema aiming to clarify the fatigue taxonomy. With special focus on cognitive fatigue, we survey the significance of objective behavioral and electrophysiological fatigue parameters and discuss the controversial literature on the relationship between subjective and objective fatigue assessment. As MS-related cognitive fatigue drastically affects quality of life, the development of efficient therapeutic approaches for overcoming cognitive fatigue is of high clinical relevance. In this regard, the reliable and valid assessment of the individual fatigue level by objective parameters is essential for systematic treatment evaluation and optimization. Transcranial electrical stimulation (tES) may offer a unique opportunity to manipulate maladaptive neural activity underlying MS fatigue. Therefore, we discuss evidence for the therapeutic potential of tES on cognitive fatigue in people with MS.

Neural Indicators of Fatigue in Chronic Diseases: A Systematic Review of MRI Studies

While fatigue is prevalent in chronic diseases, the neural mechanisms underlying this symptom remain unknown. Magnetic resonance imaging (MRI) has the potential to enable us to characterize this symptom. The aim of this review was to gather and appraise the current literature on MRI studies of fatigue in chronic diseases. We systematically searched the following databases: MedLine, PsycInfo, Embase and Scopus (inception to April 2016). We selected studies according to a predefined inclusion and exclusion criteria. We assessed the quality of the studies and conducted descriptive statistical analyses. We identified 26 studies of varying design and quality. Structural and functional MRI, alongside diffusion tensor imaging (DTI) and functional connectivity (FC) studies, identified significant brain indicators of fatigue. The most common regions were the frontal lobe, parietal lobe, limbic system and basal ganglia. Longitudinal studies offered more precise and reliable analysis. Brain structures found to be related to fatigue were highly heterogeneous, not only between diseases, but also for different studies of the same disease. Given the different designs, methodologies and variable results, we conclude that there are currently no well-defined brain indicators of fatigue in chronic diseases.

The Dyad-Adaptive Paced Auditory Serial Addition Test (DA-PASAT): Normative data and the effects of repeated testing, simulated malingering, and traumatic brain injury

The Paced Auditory Serial Addition Test (PASAT) is widely used to evaluate processing speed and executive function in patients with multiple sclerosis, traumatic brain injury, and other neurological disorders. In the PASAT, subjects listen to sequences of digits while continuously reporting the sum of the last two digits presented. Four different stimulus onset asynchronies (SOAs) are usually tested, with difficulty increasing as SOAs are reduced. Ceiling effects are common at long SOAs, while the digit delivery rate often exceeds the subject’s processing capacity at short SOAs, causing some subjects to stop performing altogether. In addition, subjects may adopt an “alternate answer” strategy at short SOAs, which reduces the test’s demands on working-memory and processing speed. Consequently, studies have shown that the number of dyads (consecutive correct answers) is a more sensitive measure of PASAT performance than the overall number of correct sums. Here, we describe a 2.5-minute computerized test, the Dyad-Adaptive PASAT (DA-PASAT), where SOAs are adjusted with a 2:1 staircase, decreasing after each pair of correct responses and increasing after misses. Processing capacity is reflected in the minimum SOA (minSOA) achieved in 54 trials. Experiment 1 gathered normative data in two large populations: 1617 subjects in New Zealand ranging in age from 18 to 65 years, and 214 Californians ranging in age from 18 to 82 years. Minimum SOAs were influenced by age, education, and daily hours of computer-use. Minimum SOA z-scores, calculated after factoring out the influence of these factors, were virtually identical in the two control groups, as were response times (RTs) and dyad ratios (the proportion of hits occurring in dyads). Experiment 2 measured the test-retest reliability of the DA-PASAT in 44 young subjects who underwent three test sessions at weekly intervals. High intraclass correlation coefficients (ICCs) were found for minSOAs (0.87), response times (0.76), and dyad ratios (0.87). Performance improved across test sessions for all measures. Experiment 3 investigated the effects of simulated malingering in 50 subjects: 42% of simulated malingerers produced abnormal (p< 0.05) minSOA z-scores. Simulated malingerers with abnormal scores were distinguished with 87% sensitivity and 69% specificity from control subjects with abnormal scores by excessive differences between training performance and the actual test. Experiment 4 investigated patients with traumatic brain injury (TBI): patients with mild TBI performed within the normal range while patients with severe TBI showed deficits. The DA-PASAT reduces the time and stress of PASAT assessment while gathering sensitive measures of dyad processing that reveal the effects of aging, malingering, and traumatic brain injury on performance.

A Longitudinal Evaluation of Cognitive Fatigue on a Task of Sustained Attention in Early Relapsing-Remitting Multiple Sclerosis

Background

Cognitive fatigue can be objectively measured on tasks of sustained attention and can be defined as decreased performance as a result of sustained cognitive effort. Individuals with multiple sclerosis (MS) early in their disease are vulnerable to cognitive fatigue, although this has yet to be evaluated longitudinally. We aimed to evaluate cognitive fatigue over a 3-year interval in individuals with early-phase relapsing-remitting MS (RRMS). The sensitivity of the Paced Auditory Serial Addition Test (PASAT) at detecting cognitive fatigue was evaluated, as was the impact of scoring method.

Methods

32 people with MS and 32 controls completed the 3- and 2-second PASAT (PASAT-3″ and -2″) as a measure of sustained attention at baseline and 3-year follow-up.

Results

Performance on the PASAT remained stable across time, with improvement noted on the PASAT-2″ likely due to practice and the small sample size. Cognitive fatigue was noted at both times, although sensitivity varied based on scoring method. No evidence of worsening cognitive fatigue was noted over time. The MS group performed worse only when cognitive fatigue was the outcome variable.

Conclusions

Although individuals with MS continue to be vulnerable to cognitive fatigue at follow-up, severity does not seem to increase with time. Cognitive fatigue may be a more sensitive marker of cognitive impairment than overall task performance in those with early-phase RRMS, which has important implications given that clinically only task performance is typically assessed.

A Taxonomy of Fatigue Concepts and Their Relation to Hearing Loss

Fatigue is common in individuals with a variety of chronic health conditions and can have significant negative effects on quality of life. Although limited in scope, recent work suggests persons with hearing loss may be at increased risk for fatigue, in part due to effortful listening that is exacerbated by their hearing impairment. However, the mechanisms responsible for hearing loss-related fatigue, and the efficacy of audiologic interventions for reducing fatigue, remain unclear. To improve our understanding of hearing loss-related fatigue, as a field it is important to develop a common conceptual understanding of this construct. In this article, the broader fatigue literature is reviewed to identify and describe core constructs, consequences, and methods for assessing fatigue and related constructs. Finally, the current knowledge linking hearing loss and fatigue is described and may be summarized as follows: Hearing impairment may increase the risk of subjective fatigue and vigor deficits; adults with hearing loss require more time to recover from fatigue after work and have more work absences; sustained, effortful, listening can be fatiguing; optimal methods for eliciting and measuring fatigue in persons with hearing loss remain unclear and may vary with listening condition; and amplification may minimize decrements in cognitive processing speed during sustained effortful listening. Future research is needed to develop reliable measurement methods to quantify hearing loss-related fatigue, explore factors responsible for modulating fatigue in people with hearing loss, and identify and evaluate potential interventions for reducing hearing loss-related fatigue.

Fatigue and Cognitive Fatigability in Mild Traumatic Brain Injury are Correlated with Altered Neural Activity during Vigilance Test Performance

Introduction

Fatigue is the most frequently reported persistent symptom following a mild traumatic brain injury (mTBI), but the explanations for the persisting fatigue symptoms in mTBI remain controversial. In this study, we investigated the change of cerebral blood flow during the performance of a psychomotor vigilance task (PVT) by using pseudo-continuous arterial spin labeling (PCASL) MRI technique to better understand the relationship between fatigability and brain activity in mTBI.

Material and methods

Ten patients (mean age: 37.5 ± 11.2 years) with persistent complaints of fatigue after mTBI and 10 healthy controls (mean age 36.9 ± 11.0 years) were studied. Both groups completed a 20-min long PVT inside a clinical MRI scanner during simultaneous measurements of reaction time and regional cerebral blood flow (rCBF) with PCASL technique. Cognitive fatigability and neural activity during PVT were analyzed by dividing the performance and rCBF data into quintiles in addition to the assessment of self-rated fatigue before and after the PVT.

Results

The patients showed significant fatigability during the PVT while the controls had a stable performance. The variability in performance was also significantly higher among the patients, indicating monitoring difficulty. A three-way ANOVA, modeling of the rCBF data demonstrated that there was a significant interaction effect between the subject group and performance time during PVT in a mainly frontal/thalamic network, indicating that the pattern of rCBF change for the mTBI patients differed significantly from that of healthy controls. In the mTBI patients, fatigability at the end of the PVT was related to increased rCBF in the right middle frontal gyrus, while self-rated fatigue was related to increased rCBF in left medial frontal and anterior cingulate gyri and decreases of rCBF in a frontal/thalamic network during this period.

Discussion

This study demonstrates that PCASL is a useful technique to investigate neural correlates of fatigability and fatigue in mTBI patients. Patients suffering from fatigue after mTBI used different brain networks compared to healthy controls during a vigilance task and in mTBI, there was a distinction between rCBF changes related to fatigability vs. perceived fatigue. Whether networks for fatigability and self-rated fatigue are different, needs to be investigated in future studies.

Operationalising cognitive fatigability in multiple sclerosis: A Gordian knot that can be cut?

BACKGROUND

Researchers have attempted to operationalise objective measures of cognitive fatigability in multiple sclerosis (MS) to overcome the perceived subjectivity of patient-reported outcomes of fatigue (PROs). Measures of cognitive fatigability examine decrements in performance during sustained neurocognitive tasks.

OBJECTIVE

This personal viewpoint briefly summarises available evidence for measures of cognitive fatigability in MS and considers their overall utility.

RESULTS

Studies suggest there may be a construct that is distinct from self-reported fatigue, reflecting a new potential intervention target. However, assessments vary and findings across and within measures are inconsistent. Few measures have been guided by a coherent theory, and those identified are likely to be influenced by other confounds, such as cognitive impairment caused more directly by disease processes, depression and assessment biases.

CONCLUSION

Future research may benefit from (a) developing a guiding theory of cognitive fatigability, (b) examining ecological and construct validity of existing assessments and (c) exploring whether the more promising cognitive fatigability measures are correlated with impaired functioning after accounting for possible confounds. Given the issues raised, we caution that our purposes as researchers may be better served by continuing our search for a more objective cognitive fatigability construct that runs in parallel with improving, rather than devaluing, current PROs.

The effect of Fampridine-SR on cognitive fatigue in a randomized double-blind crossover trial in patients with MS

BACKGROUND

Cognitive fatigue (CF) is a common complaint in persons with MS (PwMS). Fampridine-SR improves ambulation, fatigue and endurance, due to enhancing action potential formation by blocking potassium channels in demyelinated axons. Thus, through this same mechanism, it is hypothesized that Fampridine-SR could improve CF.

OBJECTIVE

To determine if Fampridine-SR objectively improves CF in PwMS.

METHODS

Sixty PwMS of any type with CF, defined as 3 or less correct responses when comparing the last third to the first third on the Paced Auditory Serial Addition Test (PASAT), were recruited from a tertiary care MS clinic in London (ON) Canada. Subjects also had to be between 18 and 64 years of age, inclusive, not had a relapse in the last 60 days or corticosteroids in the last 30 days, EDSS 0.0-7.0, and no other diagnosis that could cause cognitive impairment. A randomized double blind crossover design was used: subjects were randomized to either placebo or Fampridine-SR for 4 weeks, then after at least a one week washout, received the opposite treatment. Subjects were assessed before and after each treatment block. The primary outcome was the PASAT CF score after treatment with Fampridine-SR compared to placebo. T-tests and chi-square were used to compare demographics between the two groups (placebo-Fampridine-SR vs. Fampridine SR-placebo). Treatment effects were assessed using factorial ANOVA, with treatment (Fampridine-SR vs. placebo) and time (before and after treatment) as within-subject variables.

RESULTS

Of the 60 subjects randomized, 48 completed the study; three were removed due to an adverse event while in the treatment arm (one due to relapse while on placebo, one due to urinary retention and one due to dizziness and headache while on Fampridine-SR). The subjects had a mean age of 46.5±10.0 years, education of 13.6±1.9 years, and were diagnosed with MS 10.6±9.6 years ago. The majority were female (46, 76.7%), had relapsing remitting MS (41, 68.3%) with median EDSS of 3.5 (range 1.0-7.0). There were no significant demographic differences between the two groups. The treatment x time interaction within the factorial ANOVA on PASAT CF scores was statistically significant, F(1, 45)=8.28, p=0.006, suggesting there is a difference between the treatments (placebo vs. Fampridine-SR), over the course of the study. An evaluation of the mean scores suggests, however, that subjects saw a greater improvement when they were given the placebo, than when they were given the active medication. Similarly, individuals showed a greater increase in their information processing speed (as measured by the PASAT) over the course of treatment when they were given the placebo, as compared with the active medication F(1,45)=4.17, p=0.047.

CONCLUSION

Although this small pilot study does not suggest that Fampridine-SR results in a statistically significant improvement of CF in MS patients, as compared to placebo, individuals demonstrated an improvement in both information processing speed and CF, suggesting further studies are warranted.

Development and Validation of the State-Trait Inventory of Cognitive Fatigue in Community-Dwelling Older Adults

OBJECTIVE

To develop and validate a subjective measure of cognitive fatigue-the State-Trait Inventory of Cognitive Fatigue-in community-dwelling older adults.

DESIGN

Scale development and test construction.

SETTING

Community-dwelling older adults enrolled in a longitudinal cohort aging study.

PARTICIPANTS

Participants (N=175) were healthy, English-speaking, community-dwelling adults, age ≥65 years.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

State-Trait Inventory of Cognitive Fatigue total, cognitive fatigue, motivation, mental effort, and boredom summation scores for both state and trait forms.

RESULTS

Principal component analysis yielded the expected 4 components for both state and trait forms: cognitive fatigue, mental effort, motivation, and boredom. All components had good reliability. There was good convergent validity as measured by the strong positive relation between cognitive fatigue and a subjective measure of general fatigue, even after controlling for depressive symptoms. Greater subjective cognitive fatigue was associated with worse performance on measures thought to be more sensitive to aspects of executive functioning.

CONCLUSIONS

This study developed and established the psychometric properties of a new instrument for the subjective measurement of cognitive fatigue for use in community-dwelling older adults. The State-Trait Inventory of Cognitive Fatigue's relatively brief administration time (<10min; mean, 5.6±2.9) and strong psychometric properties support its utility in both research and clinical settings. Future studies should establish the psychometric properties of this scale in other populations and examine its predictive utility for relevant clinical outcomes.

Subjective fatigue in children with hearing loss: some preliminary findings

PURPOSE

In this study, the authors examined the effect of hearing loss on subjective reports of fatigue in school-age children using a standardized measure.

METHODS

As part of a larger ongoing study, the authors obtained subjective ratings of fatigue using the Pediatric Quality of Life Inventory (PedsQL) Multidimensional Fatigue Scale ( Varni, Burwinkle, Katz, Meeske, & Dickinson, 2002). This standardized scale provides a measure of general fatigue, sleep/rest fatigue, cognitive fatigue, and an overall composite measure of fatigue. To date, data from 10 children with hearing loss (CHL) and 10 age-matched children with normal hearing (CNH) have been analyzed.

RESULTS

These preliminary results show that subjective fatigue is increased in school-age children with hearing loss (Cohen's d = 0.78-1.90). In addition, the impact of hearing loss on fatigue in school-age children appears pervasive across multiple domains (general, sleep/rest, and cognitive fatigue).

CONCLUSION

School-age CHL reported significantly more fatigue than did CNH. These preliminary data are important given the negative academic and psychosocial consequences associated with fatigue. Further research is needed to determine the underlying mechanisms responsible for this increased fatigue in school-age children with hearing loss, and to identify factors that may modulate (e.g., degree of loss) and mediate (e.g., hearing aid or cochlear implant use) its impact.

An investigation of attention, executive, and psychomotor aspects of cognitive fatigability

OBJECTIVE

Self-perceived mental fatigue is a common presenting symptom in many neurological diseases. Discriminating objective fatigability from self-perceived mental fatigue might facilitate neuropsychological diagnosis and treatment programs. However clinically valid neuropsychological instruments suitable for assessment of fatigability are still lacking. The prime aim of the study was to investigate aspects of cognitive fatigability and to identify properties of neuropsychological tests suitable to assess fatigability in patients with persistent cognitive complaints after mild brain injury. Another aim was to investigate whether cognitive fatigability captured by neuropsychological measures is influenced by depression or sleep disturbances.

METHOD

Twenty-four patients with persistent cognitive symptoms after mild traumatic brain injury (mTBI), (aged 18-51 years) and 31 healthy controls (aged 20-49 years) underwent neuropsychological testing measuring three cognitive fatigability domains: Attention fatigability was assessed using the Ruff 2 & 7 Selective Attention Test, executive fatigability using the Color Word Test (Stroop), and psychomotor fatigability using the Digit Symbol Substitution Test from the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III). Subjective fatigue was measured using the Fatigue Severity Scale and a questionnaire of everyday consequences of fatigue. Depression was screened using the Hospital Anxiety and Depression Scale and sleep disturbances using the Pittsburgh Sleep Quality Index.

RESULTS

The patients reported significantly more mental fatigue and performed worse on tests of psychomotor and executive fatigability than the healthy controls. Furthermore, the cognitive fatigability measures were not influenced by depression or sleep disturbances, as was the case in self-reported fatigue.

CONCLUSION

Tests demanding executive or simultaneous processing of several neuropsychological functions seem most sensitive in order to capture cognitive fatigability. Clinical tests that can capture fatigability enable a deeper understanding of how fatigability might contribute to cognitive complaints and problems in maintaining daily activities.

White matter abnormalities and working memory impairment in systemic lupus erythematosus

OBJECTIVE/BACKGROUND

Many patients with systemic lupus erythematosus (SLE) have working memory deficits. Few studies have evaluated working memory performance and neurometabolite profile using magnetic resonance spectroscopy in SLE.

METHODS

We gave the Paced Auditory Serial Addition Test (PASAT), a measure of working memory, to 73 patients with SLE. We calculated total score, dyads, chunking, and cognitive fatigue. Using magnetic resonance spectroscopy, we determined the ratio of choline to creatine (Ch/Cr) in normal-looking right and left frontal lobe white matter.

RESULTS

Twenty-nine percent of patients showed impaired working memory on the PASAT. Total PASAT score inversely correlated with right and left frontal white matter Ch/Cr. Left frontal white matter Ch/Cr correlated with percent chunking and inversely correlated with total and percent dyads. Right frontal white matter Ch/Cr correlated with percent chunking and inversely correlated with total and percent dyads. There was no relationship between cognitive fatigue and either left or right frontal white matter Ch/Cr. Longer disease duration was associated with higher left frontal white matter Ch/Cr. Correlations remained significant when we considered disease duration and left frontal white matter Ch/Cr against total PASAT score and total dyads.

CONCLUSIONS

Patients with SLE were impaired on the PASAT. Lower total PASAT score and fewer dyads correlated with higher left frontal microstructural white matter damage, while cognitive fatigue did not. This pattern suggests that early white matter damage interferes with working memory in SLE and provides further insight into the neurobiological basis of mild cognitive dysfunction related to microstructural white matter injury.