Selective impairment of auditory processing in chronic fatigue syndrome: a comparison with multiple sclerosis and healthy controls

The Effect of Fatigue on Working Memory and Auditory Perceptual Abilities in Trained Musicians

Purpose Many perceptual processing processes, such as cognition, vision, sensation, and audition, are affected due to fatigue. Musicians are prone to fatigue because of long working hours and demanding profession. The research on assessing working memory abilities in musicians is heterogeneous, as none of the studies has controlled the effect of fatigue. This study was thus designed to assess the effect of fatigue on working memory and auditory perception in trained instrumental musicians. Method Twenty-six trained instrumental musicians and 25 nonmusicians participated in this study. The effect of fatigue was assessed by administering the working memory and auditory perception tests in prefatigue and postfatigue conditions. The fatigue was assessed using a 100-point visual analog scale. The working memory was assessed using Operation Span, Reading Span, and Digit Span (Forward and Backward) tests (Knutson et al., 1991). Auditory perception was assessed using speech-perception-in-noise and temporal integration tests. Results Working memory and speech perception were affected due to fatigue. Musicians, despite having better working memory abilities than nonmusicians, are equally prone to fatigue-related distress. Conclusion The advantage of music training for the working memory abilities may be reduced due to fatigue; hence, measures to reduce fatigue should be employed by the musicians. Fatigue should also be treated as a variable in all future research related to assess cognitive processing in musicians.

A unifying theory for cognitive abnormalities in functional neurological disorders, fibromyalgia and chronic fatigue syndrome: systematic review

BACKGROUND

Functional cognitive disorder (FCD) describes cognitive dysfunction in the absence of an organic cause. It is increasingly prevalent in healthcare settings yet its key neuropsychological features have not been reported in large patient cohorts. We hypothesised that cognitive profiles in fibromyalgia (FM), chronic fatigue syndrome (CFS) and functional neurological disorders (FNDs) would provide a template for characterising FCD.

METHODS

We conducted a systematic review of studies with cognition-related outcomes in FM, CFS and FND.

RESULTS

We selected 52 studies on FM, 95 on CFS and 39 on FND. We found a general discordance between high rates of subjective cognitive symptoms, including forgetfulness, distractibility and word-finding difficulties, and inconsistent objective neuropsychological deficits. Objective deficits were reported, including poor selective and divided attention, slow information processing and vulnerability to distraction. In some studies, cognitive performance was inversely correlated with pain, exertion and fatigue. Performance validity testing demonstrated poor effort in only a minority of subjects, and patients with CFS showed a heightened perception of effort.

DISCUSSION

The cognitive profiles of FM, CFS and non-cognitive FND are similar to the proposed features of FCD, suggesting common mechanistic underpinnings. Similar findings have been reported in patients with mild traumatic brain injury and whiplash. We hypothesise that pain, fatigue and excessive interoceptive monitoring produce a decrease in externally directed attention. This increases susceptibility to distraction and slows information processing, interfering with cognitive function, in particular multitasking. Routine cognitive processes are experienced as unduly effortful. This may reflect a switch from an automatic to a less efficient controlled or explicit cognitive mode, a mechanism that has also been proposed for impaired motor control in FND. These experiences might then be overinterpreted due to memory perfectionism and heightened self-monitoring of cognitive performance.

Processing speed versus working memory: contributions to an information-processing task in multiple sclerosis

Individuals with multiple sclerosis (MS) often experience cognitive impairments in information processing. However, the relative contributions of processing speed abilities and working memory abilities to information-processing tasks are not yet fully understood. The current study examined the extent to which processing speed and/or working memory abilities contributed to an information-processing task, the Keeping Track Task (KTT). Forty-nine individuals with MS were given tests to assess processing speed and working memory, as well as the KTT. Regression analyses indicated that in the MS group, processing speed abilities accounted for the majority of the explained variance in KTT performance. The findings suggest that processing speed plays a significant role on KTT performance in MS. Implications for cognitive rehabilitation treatments aimed at improving processing speed abilities in MS are discussed.

Cognitive functioning in chronic fatigue syndrome: a meta-analysis

BACKGROUND

Cognitive problems are commonly reported in persons with chronic fatigue syndrome (CFS) and are one of the most disabling symptoms of this condition. A number of cognitive deficits have been identified, although the findings are inconsistent and hindered by methodological differences. The current study therefore conducted a meta-analysis of research examining cognitive functioning in persons with CFS in order to identify the pattern and magnitude of any deficits that are associated with this condition.

METHOD

A comprehensive search of the PubMed and PsycINFO databases for studies that examined cognitive functioning in CFS between 1988 and 2008 identified 50 eligible studies. Weighted Cohen's d effect sizes, 95% confidence intervals and fail-safe Ns were calculated for each cognitive score.

RESULTS

Evidence of cognitive deficits in persons with CFS was found primarily in the domains of attention, memory and reaction time. Deficits were not apparent on tests of fine motor speed, vocabulary, reasoning and global functioning.

CONCLUSIONS

Persons with CFS demonstrate moderate to large impairments in simple and complex information processing speed and in tasks requiring working memory over a sustained period of time.

[Cognitive impairment]

Cognitive impairment is common in multiple sclerosis (MS), occurring at all stages of the disease, even at the earliest, and can be a major source of disability, social impairment, and impoverished quality of life. Cognitive dysfunction is mainly focused on working memory, conceptual reasoning, verbal fluency, speed of information processing, attention and executive function. Measures of information-processing speed appear to be the most robust and sensitive markers of cognitive impairment in MS patients. Cognitive testing in MS patients is complex and cognitive screening tests are time- and cost-saving test instruments. A comprehensive and sensitive cognitive test procedure should be administered to detect cognitive dysfunction, and recent studies demonstrate that single, predominantly speed-related cognitive tests may be superior to extensive and time-consuming test batteries in screening cognitive decline. Additional clinical factors, including disease course, fatigue, and affective disturbance, can impact the degree of MS-related cognitive impairment. Despite weak correlation with disease duration and physical disability status, the degree of cognitive impairment in MS has been related to the extent of topographically specific neuronal tissue damage and loss. Numerous studies have applied conventional and quantitative magnetic resonance imaging (MRI) techniques to correlate the profile and degree of cognitive impairment with various MRI-detectable abnormalities. The burden of MRI-visible lesions does not fully account for the degree of MS-related cognitive impairment. Nonconventional MRI findings suggest the extent of subtle tissue damage in normal-appearing white and grey matter to correlate best with the severity of cognitive impairment in MS patients. Structural MRI approaches have recently been extended by functional MRI studies scrutinizing the brain's ability for adaptive functional reorganization in the presence of widespread tissue damage. Cognitive impairment in MS seems to be not simply the result of tissue destruction, but also a balance between tissue destruction, tissue repair, and adaptive functional reorganization. These findings highlight the need to screen for cognitive deficits in MS patients to conduct potential cognitive rehabilitation intervention.

Chronic fatigue syndrome: a systematic review

OBJECTIVE

A systematic review of the literature about chronic fatigue syndrome (CFS).

METHODS

A search of the Medline database (via Ovid and PubMed) with the key words chronic fatigue syndrome, diagnosis, classification, epidemiology, etiology, physiopathology, metabolism, microbiology, immunology, virology, psychology, drug therapy, rehabilitation, and therapy. The reference lists of each article were examined for additional related articles.

RESULTS

CFS was defined in 1988 by the US Centes for Disease Control and Prevention. The prevalence of chronic fatigue syndrome has ranged from 0.2% to 0.7% in the general population. In 1994, the definition of CFS was revised by Fukuda et al. Despite various research in several topics (e.g. infection, immune systems, neuroendocrinology, autonomic activity, neuromuscular involvement), the pathophysiology remains unknown.

CONCLUSION

CFS, with its various major clinical and functional impacts, should be associated with a "biopsychosocial model". Progressive muscular rehabilitation, combined with behavioral and cognitive treatment, is an essential part of therapy.

Paced visual serial addition test in multiple sclerosis

The paced auditory serial addition test (PASAT), a subtest of the multiple sclerosis functional composite score (MSFC), is increasingly used in the evaluation of cognitive function in multiple sclerosis (MS). While patient acceptance for the PASAT is low, its visual version, the paced visual serial addition test (PVSAT), is perceived to be better tolerated. The aim of this study was to investigate the interchangeability of PVSAT and PASAT in the evaluation of cognitive function in MS. Twenty-one normal controls and 50 patients with clinically definite MS were tested with PASAT and PVSAT. Both for PASAT and PVSAT, 3 and 2-second versions of two parallel test forms were used. In the PVSAT, the PASAT stimuli were shown on a computer screen. Patients were also tested with the other two MSFC subtests, i.e. the nine-hole pegboard test and timed 25-foot walk test, to calculate MSFC scores. PASAT-3 correlated highly with both PVSAT-3 and PVSAT-2. MSFC-v scores calculated with PVSAT-2 and PVSAT-3 values correlated highly with MSFC scores calculated with PASAT-3 results. The results suggest that the PVSAT can be used as an alternative for the PASAT in the MSFC.

Functionality or aesthetics?A pilot study of music therapy in the treatment of multiple sclerosis patients

INTRODUCTION

Neuro-degenerative diseases are, and will remain, an enormous public health problem. Interventions that could delay disease onset even modestly will have a major public health impact. The aim of this study is to see which components of the illness are responsive to change when treated with music therapy in contrast to a group of patients receiving standard medical treatment alone.

MATERIAL AND METHODS

Twenty multiple sclerosis patients (14 female, 6 male) were involved in the study, their ages ranging from 29 to 47 years. Ten participants formed the therapy group, and 10 the matched control group matched by age, gender and the standard neurological classification scheme Expanded Disability Status Scale (EDSS). Exclusion criteria were pregnancy and mental disorders requiring medication. Patients in the therapy group received three blocks of music therapy in single sessions over the course of the one-year project (8-10 sessions, respectively). Measurements were taken before therapy began (U1), and subsequently every three months (U2-U4) and within a 6-month follow-up without music therapy (U5) after the last consultation. Test battery included indicators of clinical depression and anxiety (Beck Depression Inventory and Hospital Anxiety and Depression Scale), a self-acceptance scale (SESA) and a life quality assessment (Hamburg Quality of Life Questionnaire in Multiple Sclerosis). In addition, data were collected on cognitive (MSFC) and functional (EDSS) parameters.

RESULTS

There was no significant difference between the music-therapy treatment group and the control group. However, the effect size statistics comparing both groups show a medium effect size on the scales measuring self-esteem (d, 0.5423), depression HAD-D (d, 0.63) and anxiety HAD-A (d, 0.63). Significant improvements were found for the therapy group over time (U1-U4) in the scale values of self-esteem, depression and anxiety. In the follow-up, scale values for fatigue, anxiety and self-esteem worsen within the group treated with music therapy.

DISCUSSION

A therapeutic concept for multiple sclerosis, which includes music therapy, brings an improvement in mood, fatigue and self-acceptance. When music therapy is removed, then scale scores worsen and this appears to intimate that music therapy has an influence.

Neuropsychological deficits in patients with chronic fatigue syndrome

The degree of neuropsychological dysfunction across multiple domains was examined in individuals suffering from chronic fatigue syndrome (CFS). In this descriptive study, a similar series of neuropsychological tests was administered to a group of CFS patients and healthy participants. More specifically, CFS patients (n = 141) who met the 1994 Case Definition criteria were compared to 76 healthy control participants on tests of memory, attention (concentration), speed of information processing, motor speed, and executive functioning. On the 18 measures administered, CFS patients scored 1 standard deviation below the healthy mean on nine measures and scored 2 standard deviations below the healthy mean on four of the measures. Moreover, results indicated that CFS patients were more likely than healthy controls to fail (1.6 SD below the healthy mean) at least one test in each of the following domains: attention, speed of information processing, and motor speed, but not on measures of memory and executive functioning. Finally, CFS patients demonstrated a greater total number of tests failed across domains.

Mapping the neural systems that mediate the Paced Auditory Serial Addition Task (PASAT)

The paced auditory serial addition task (PASAT), in which subjects hear a number-string and add the two most-recently heard numbers, is a neuropsychological test sensitive to cerebral dysfunction. We mapped the brain regions activated by the PASAT using positron emission tomography (PET) and 15O-water to measure cerebral blood flow. We parsed the PASAT by mapping sites activated by immediate repetition of numbers and by repetition of the prior number after the presentation of the next number in the series. The PASAT activated dispersed non-contiguous foci in the superior temporal gyri, bifrontal and biparietal sites, the anterior cingulate and bilateral cerebellar sites. These sites are consistent with the elements of the task that include auditory perception and processing, speech production, working memory, and attention. Sites mediating addition were not identified. The extent of the sites activated during the performance of the PASAT accounts for the sensitivity of this test and justifies its use in a variety of seemingly disparate conditions.

Working memory deficits in chronic fatigue syndrome: differentiating between speed and accuracy of information processing

To examine the relative influence of speed of information processing versus working memory ability, CFS participants with psychiatric comorbidity (CFS-Psych) and CFS without a psychiatric history (CFS-noPsych) were examined on tests of visual and auditory processing speed and visual and auditory working memory. Compared to healthy controls (HC) and a group of participants with rheumatoid arthritis (RA), the CFS-noPsych group displayed significantly reduced performance on tests of information processing speed, but not on tests of working memory. No significant differences were observed between the CFS-Psych group and any other group in the study. The implications of group heterogeneity on the understanding of cognitive impairment in CFS are discussed.

Correlates of illness worry in chronic fatigue syndrome

BACKGROUND

Anxiety about illness leading to restriction of activity and physical deconditioning has been hypothesized to contribute to the chronicity of fatigue. Pathological symptom attributions, personality traits, and depression have all been hypothesized to contribute to illness worry.

METHODS

We compared 45 chronic fatigue syndrome (CFS) and 40 multiple sclerosis (MS) outpatients using a battery of psychometric instruments comprising the 12-item Illness Worry scale, the Symptom Interpretation Questionnaire (SIQ), the NEO Five-Factor Inventory (NEO-FFI), and a modified version of the SCL-90R Depression scale.

RESULTS

There was no difference between the two diagnostic groups on neuroticism, depressive symptoms, as well as the three scales of the SIQ. On the illness worry index, the CFS group had significantly higher scores than the MS group. This difference was due to items tapping vulnerability to illness and the perception that others are not taking their illness seriously. Somatic attributional style, neuroticism, depressive symptoms, and age were all significant predictors of illness worry in both CFS and MS patients.

CONCLUSIONS

Somatic attributions, neuroticism, and depression all contribute to illness worry in chronic illness. However, these factors do not account for the higher levels of illness worry in CFS as opposed to MS, which may be due to other specific cognitive and social interactional processes.

Cognitive functioning in chronic fatigue syndrome and the role of depression, anxiety, and fatigue

OBJECTIVE

This study was designed to investigate the role of depression, anxiety, and fatigue in Chronic Fatigue Syndrome (CFS) sufferers' objective and subjective cognitive performance.

METHODS

Twenty-three CFS sufferers and 23 healthy control participants were compared on objective and subjective assessments of cognitive performance. Depression, anxiety, and fatigue were also evaluated.

RESULTS

CFS sufferers did not demonstrate any impairment in objective cognitive functioning compared to the control group, and objective performance was not related to their higher levels of depression or their level of fatigue. Depression scores only accounted for a small amount of the variance in CFS sufferers' lower subjective assessment of their cognitive performance compared to control participants. There were no differences between the groups on anxiety scores.

CONCLUSION

The results are discussed in terms of the heterogeneity of the CFS population and the complex interaction of symptomatological factors that characterise CFS.

Paced Visual Serial Addition Test: an alternative measure of information processing speed

The Paced Auditory Serial Addition Test (PASAT; Gronwall, 1977; Gronwall & Sampson, 1974) is a measure of attention and information processing speed sensitive to mild traumatic brain injury (MTBI), but it is aversive and inappropriate for many other neurologically impaired patients. This study examines a simpler, less aversive visual analog of the PASAT (the Paced Visual Serial Addition Test; PVSAT) in a sample of 74 college students (26 with a history of TBI). Results indicated that the PVSAT is moderately correlated with and less difficult than the PASAT. Both tests had identical relations to other measures of attention. Neither the PVSAT, PASAT, nor the other attentional measures differentiated participants with MTBI from normal controls in a college population. This preliminary study thus demonstrates the comparability of the two tests and presents the PVSAT as a viable alternative to the PASAT. Directions for future research and applications of these findings are discussed.

Neuropsychological functioning in chronic fatigue syndrome: a review

OBJECTIVE

In this paper we review critically the current status of neurocognitive studies in patients with chronic fatigue syndrome (CFS).

METHOD

CFS literature was monitored as part of a large research project which involved several neuropsychological and psychopathological studies. The literature survey was the result of several consecutive searches on Medline and PsycInfo databases.

RESULTS

The neurocognitive studies are reviewed in terms of scientificaly accepted aspects of attention and memory. In addition, we review possible explanations for cognitive dysfunction in CFS. This is preceded with a discussion of the methodological limitations that are considered to explain inconcistencies across neuropsychological studies in CFS.

CONCLUSION

The current research shows that slowed processing speed, impaired working memory and poor learning of information are the most prominent features of cognitive dysfunctioning in patients with CFS. Furthermore, to this date no specific pattern of cerebral abnormalities has been found that uniquely characterizes CFS patients. There is no overwhelming evidence that fatigue is related to cognitive performance in CFS, and researchers agree that their performance on neuropsychological tasks is unlikely to be accounted solely by the severity of the depression and anxiety.

Speed of information processing in traumatic brain injury: modality-specific factors

OBJECTIVE

To assess speed of information processing by two serial addition tests (one visual, one auditory) in individuals with moderate-to-severe traumatic brain injuries (TBIs) and in a healthy, normal control group (NC). The tasks were designed to equate and control for accuracy of performance across the TBI and NC groups, thus allowing for quantification of information processing speed.

DESIGN

Performance across groups and tasks were compared using 2 x 2 repeated measure analyses of variance (ANOVAs). In addition, each individual's processing speed was used to adjust rate of stimulus presentation on a subsequent "rehabilitation" trial to determine further whether this adjustment equated accuracy of performance.

SETTING

Rehabilitation hospital.

PATIENTS

22 outpatients with moderate-to-severe TBI (6 women, 16 men; mean age = 34.6 years; duration of loss of consciousness = 22.6 days) and 20 age- and education-matched healthy controls.

RESULTS

Processing speed was slower in TBI subjects, relative to controls and was significantly related to measures of executive functioning for those with TBI. Relative to controls, speed of processing in the TBI group was disproportionately slower when information was presented in the auditory, relative to the visual, modality.

CONCLUSIONS

Speed of information processing is a major impairment in those with TBI when unconfounded by performance accuracy. The modality-specific impairment observed in the TBI group may, in part, be due to a greater within-modality interference effect created by the auditory version of the task. By manipulating information at a pace customized for an individual through compensatory strategies and environmental modifications, information-processing performance of TBI participants can be enhanced significantly.

Chronic fatigue syndrome: reviewing the research findings

This article reviews the current state of research in chronic fatigue syndrome (CFS). The evolving definition, prevalence, and prognosis of this controversial illness are presented. We review studies examining psychiatric, personality, and psychosocial etiology for CFS. The evidence for pathophysiology in CFS is also presented, and studies investigating viral, immune, neuroimaging, neuroendocrine, and central and autonomic nervous system abnormalities in CFS are assessed. Current evidence indicates that CFS is multi-determined and heterogeneous and that subgrouping patients according to factors such as psychiatric state and symptom onset may be fruitful. The current state of treatment for CFS is reviewed, and the challenges for research aimed at resolving this prototypical mind/body problem are discussed.

Influence of exhaustive treadmill exercise on cognitive functioning in chronic fatigue syndrome

The purpose of this study was to determine the effect of exhaustive exercise on cognitive performance of patients with chronic fatigue syndrome (CFS) and sedentary healthy controls (CON). Subjects were 19 women with CFS and 20 CON. A test battery consisting of 4 cognitive tests (CTB) was given pre-, immediately post-, and 24 hours post-treadmill exercise to exhaustion. No differences were seen on the CTB pre-exercise. CFS patients improved at a slower rate than CON on the Symbol Digit Modalities Test (SDMT), Stroop Word Test (SWT), and Stroop Color Test (SCT). When compared with CON, a lower number of correct responses was seen for the CFS immediately postexercise on the SDMT (61 +/- 3 vs 66 +/- 2), SWT (137 +/- 6 vs 146 +/- 6), and SCT (99 +/- 4 vs 107 +/- 3), and 24 hours postexercise on the SDMT (64 +/- 3 vs 69 +/- 2), SWT (134 +/- 7 vs 148 +/- 5), and SCT (101 +/- 4 vs 106 +/- 3). We conclude that after physically demanding exercise, CFS subjects demonstrated impaired cognitive processing compared with healthy individuals.

Chronic fatigue syndrome: an update

Among the many patients who seek medical care for the complaint of fatigue, a small number suffer from chronic fatigue syndrome (CFS). CFS is a poorly understood condition characterized by debilitating fatigue and associated symptoms lasting at least six months. Studies indicate that the illness is not simply a manifestation of an underlying psychiatric disorder, but rather is an illness characterized by activation of the immune system, various abnormalities of several hypothalamic-pituitary axes, and reactivation of certain infectious agents.

Poor concentration and the ability to process information after glandular fever

The symptom of poor concentration and the ability to process information were measured prospectively in 245 subjects three times in the 6 months after glandular fever or an ordinary upper respiratory tract infection. The effects of the different infections, having a fatigue state, a psychiatric disorder, sleep disturbance, and estimates of premorbid intelligence were also assessed. The most frequent complaint of poor concentration and the worst information processing occurred at the onset of the infection, but these problems decreased over time, and were not related to each other. Multiple regression modeling showed that higher socioeconomic class and vocabulary IQ were associated with information processing ability at all three interviews. In contrast, logistic regression modeling showed that the symptom of poor concentration was associated with the severity of general psychiatric morbidity (CIS score) followed by suffering from a fatigue state. These results suggest that the ability to process information after these particular infections is related to estimates of premorbid IQ, whereas poor concentration is related independently to both psychiatric morbidity and a fatigue state, but not the particular infection itself.

The Effects of Fatigue on Neuropsychological Performance in Patients With Chronic Fatigue Syndrome, Multiple Sclerosis, and Depression

The effects of fatigue on neuropsychological performance were examined in patients with fatiguing illnesses. Repeated testing with the Paced Auditory Serial Addition Test (PASAT; Gronwall, 1977) was employed over the course of a demanding neuropsychological testing session. It was hypothesized that if fatigue affects performance, one would expect to observe "blunting" of the PASAT practice effect. Fifteen of the study participants live with chronic fatigue syndrome (CFS), 15 with multiple sclerosis (MS), 14 with depression (DEP), and 15 are healthy, sedentary controls. Overall PASAT performance was significantly reduced for CFS and DEP participants compared to controls, whereas mean performance did not differ across the three fatiguing illness groups. Degree of improvement across trials (i.e., practice effect) for the groups did not differ from controls'. Neither subjective fatigue or DEP were significantly related to PASAT performance. These findings suggest that fatigue does not universally impair performance during neuropsychological assessment even in groups in which fatigue is a prominent symptom.

Neuropsychology of chronic fatigue syndrome: a critical review

This article provides a comprehensive and critical review of the neuropsychological and related literature on chronic fatigue syndrome (CFS). Despite the methodological limitations observed in several studies, some consistent findings are noted. The most consistently documented neuropsychological impairments are in the areas of complex information processing speed and efficiency. General intellectual abilities and higher order cognitive skills are intact. Emotional factors influence subjective report of cognitive difficulty, whereas their effect on objective performance remains uncertain. Although the neuropathological processes underlying cognitive dysfunction in CFS are not yet known, preliminary evidence suggests the involvement of cerebral white matter. Directions for future research are outlined.

The question of disproportionate impairments in visual and auditory information processing in multiple sclerosis

The present study was conducted to investigate the hypothesis that subjects with MS have a disproportionate impairment in the phonological loop of working memory and whether such impairment is domain-specific. This was assessed by comparing performance in subjects with MS across both the visual (using the Paced Visual Serial Addition Test: PVSAT) and auditory (using the Paced Auditory Serial Addition Test: PASAT) domains. In addition, we assessed the role of processing speed in mediating performance deficits. The results showed that: (1) Although all subjects performed better on the PVSAT versus the PASAT, no disproportionate modality-specific differences were observed in the MS group relative to controls; and (2) the rate of decline across trials in the MS and healthy control groups did not differ on either the PVSAT or PASAT. Implications of the results are discussed within the context of a working memory model.