Cognitive functioning in patients with chronic fatigue syndrome

Systematic review and meta-analysis of cognitive impairment in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is commonly associated with cognitive complaints. To bring out the neuropsychological symptomatology inherent to ME/CFS, we conducted a systematic review according to PRISMA and MOOSE guidelines of the literature through the analysis of 764 studies published between 1988 and 2019 by using PubMed Central website and Clarivate analytics platform. We performed a meta-analysis to delineate an idea of the neuropsychological profile inherent in ME/CFS. The clinical picture typically affects visuo-spatial immediate memory (g = - 0.55, p = 0.007), reading speed (g = - 0.82, p = 0.0001) and graphics gesture (g = - 0.59, p = 0.0001). Analysis also revealed difficulties in several processes inherent in episodic verbal memory (storage, retrieval, recognition) and visual memory (recovery) and a low efficiency in attentional abilities. Executive functions seemed to be little or not affected and instrumental functions appeared constantly preserved. With regard to the complexity and heterogeneity of the cognitive phenotype, it turns out that determining a sound clinical picture of ME/CFS cognitive profile must go through a neuropsychological examination allowing a complete evaluation integrating the notion of agreement between the choice and the number of tests and the complexity intrinsic to the pathology.

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.

Force Increase in a Repetitive Motor Task Inducing Motor Fatigue

To evaluate task induced motor fatigue in a well-established finger tapping task, we analyzed tapping parameters and included the time course of measures of force. We hypothesized that a decline in tapping force would reflect task induced motor fatigue, defined by a lengthening of inter-tap intervals (ITI). A secondary aim was to investigate the reliability of tapping data acquisition with the force sensor. Results show that, as expected, tapping speed decreased linearly over time, due to both an increase of ITI and tap duration. In contrast, tapping force increased non-linearly over time and was uncorrelated to changes in tapping speed. Force data could serve as a measure to characterize task induced motor fatigue. Force sensors can assess a decline in tapping speed as well as an independent increase of tapping force. We argue that the increase of force reflects central compensation, i.e. perception of fatigue, due to an increase in task effort and difficulty.

Benefits of resistance exercise in lean women with fibromyalgia: involvement of IGF-1 and leptin

Background

Chronic pain and fatigue improves by exercise in fibromyalgia (FM) but underlying mechanisms are not known. Obesity is increased among FM patients and associates with higher levels of pain. Symptom improvement after aerobic exercise is affected by body mass index (BMI) in FM. Metabolic factors such as insulin-like growth factor 1 (IGF-1) and leptin may be involved. In this study, the aim was to evaluate the role of metabolic factors in lean, overweight and obese women during resistance exercise, in relation to symptom severity and muscle strength in women with FM.

Methods

Forty-three women participated in supervised progressive resistance exercise, twice weekly for 15-weeks. Serum free and total IGF-1, IGF-binding protein 3 (IGFBP3), adiponectin, leptin and resistin were determined at baseline and after 15-weeks. Level of current pain was rated on a visual analogue scale (0–100 mm). Level of fatigue was rated by multidimensional fatigue inventory (MFI-20) subscale general fatigue (MFIGF). Knee extension force, elbow flexion force and handgrip force were assessed by dynamometers.

Results

Free IGF-1 (p = 0.047), IGFBP3 (p = 0.025) and leptin (p = 0.008) were significantly decreased in lean women (n = 18), but not in the overweight (n = 17) and the obese (n = 8). Lean women with FM benefited from resistance exercise with improvements in current pain (p= 0.039, n = 18), general fatigue (MFIGF, p = 0.022, n = 18) and improved elbow-flexion force (p = 0.017, n = 18). In overweight and obese women with FM there was no significant improvement in pain or fatigue but an improvement in elbow flexion (p = 0.049; p = 0.012) after 15 weeks of resistance exercise.

Conclusion

The clearest clinical response to resistance exercise was found in lean patients with FM. In these individuals, individualized resistance exercise was followed by changes in IGF-1 and leptin, reduced pain, fatigue and improved muscular strength. In overweight and obese women FM markers of metabolic signaling and clinical symptoms were unchanged, but strength was improved in the upper limb. Resistance exercise combined with dietary interventions might benefit patients with FM and overweight.

Trial registration

The trial was registered 21 of October 2010 with ClinicalTrials.gov identification number: NCT01226784.

Cognitive impairment in fatigue and sleepiness associated conditions

Although relating to very different concepts, sleepiness and fatigue are often confounded. However, both fatigue-associated conditions such as the chronic fatigue syndrome (CFS) and sleepiness-associated conditions such as the sleep apnea-hypopnea syndrome (SAHS) are associated with cognitive impairment with impaired attention, concentration and memory performances. Fifteen pure CFS patients, without primary sleep disorders or clinically relevant sleepiness, were compared to 15 untreated SAHS patients, without clinically relevant fatigue, and to 16 healthy controls of similar age. The auditory verbal learning test (AVLT), digit span, digit symbol and finger tapping test (FTT) were used as cognitive and behavioural measures. In addition we assessed daytime EEG spectral power and P300 evoked potentials. With exception for the digit span, all tests showed lower performances in patient groups. Recall on the AVLT did not differ between the two patient groups, but the digit and symbol spans showed more severe impairment in SAHS patients. Psychomotor performance on the FTT presented with slower hit rates in SAHS than in CFS. EEG theta power was highest in CFS patients. P300 latencies and amplitudes did not differ between groups. Fatigue- and sleepiness-associated conditions can both present with significant and objective impairment of cognitive functioning and behavioural motor performance. In our sample cognitive impairment and psychomotor performance were worse when associated to sleepiness in SAHS than with fatigue in CFS.

Low visual information-processing speed and attention are predictors of fatigue in elementary and junior high school students

Background

Fatigue is a common complaint among elementary and junior high school students, and is known to be associated with reduced academic performance. Recently, we demonstrated that fatigue was correlated with decreased cognitive function in these students. However, no studies have identified cognitive predictors of fatigue. Therefore, we attempted to determine independent cognitive predictors of fatigue in these students.

Methods

We performed a prospective cohort study. One hundred and forty-two elementary and junior high school students without fatigue participated. They completed a variety of paper-and-pencil tests, including list learning and list recall tests, kana pick-out test, semantic fluency test, figure copying test, digit span forward test, and symbol digit modalities test. The participants also completed computerized cognitive tests (tasks A to E on the modified advanced trail making test). These cognitive tests were used to evaluate motor- and information-processing speed, immediate and delayed memory function, auditory and visual attention, divided and switching attention, retrieval of learned material, and spatial construction. One year after the tests, a questionnaire about fatigue (Japanese version of the Chalder Fatigue Scale) was administered to all the participants.

Results

After the follow-up period, we confirmed 40 cases of fatigue among 118 students. In multivariate logistic regression analyses adjusted for grades and gender, poorer performance on visual information-processing speed and attention tasks was associated with increased risk of fatigue.

Conclusions

Reduced visual information-processing speed and poor attention are independent predictors of fatigue in elementary and junior high school students.

Psychomotor function and response inhibition in chronic fatigue syndrome

Most research points to cognitive slowing in chronic fatigue syndrome (CFS), although there have been negative reports. The present study is one of few that examines fine motor processing and the inhibition of automatic responses in a well-characterised CFS population. A total of 35 female CFS patients without current major depression and 25 female controls performed two computerised figure-copying tasks. The cognitive and fine motor processing of visual-spatial information was measured by recording reaction time (RT) and movement time (MT), respectively. The inhibition of automatic responses was assessed by introducing 'conflicting patterns' (i.e., patterns that were difficult to draw from the preferred left to right). A multivariate general linear model was adopted for the statistical analysis of the movement recordings. As a result, CFS was significantly associated with longer RT and MT in the pooled and in the task-specific analyses. However, there was no interaction between disease status and conflicting character of the patterns. In conclusion, these performance data on the figure-copying tasks provide confirmatory evidence for psychomotor slowing in CFS, but not for a disturbed inhibition of automatic responses. Computerised figure-copying tasks may be promising tools for use in neurobiological research and clinical trials in CFS.

What to do about attention and memory problems in children with CFS/ME: a neuropsychological approach

Our recent research has shown that children with chronic fatigue syndrome/myalgic encephalomyopathy (CFS/ME) describe problems with focused attention, sustained attention, recall and stress. Neuropsychological testing demonstrated lower scores for sustained attention, switching attention, divided attention, auditory learning and immediate recall compared to normative data. This paper describes what is currently known about memory and attention problems in children with CFS/ME and suggests a variety of strategies that could be used to overcome these difficulties.

Cognitive deficits in patients with chronic fatigue syndrome compared to those with major depressive disorder and healthy controls

OBJECT

Chronic fatigue syndrome (CFS) patients report usually cognitive complaints. They also have frequently comorbid depression that can be considered a possible explanation for their cognitive dysfunction. We evaluated the cognitive performance of patients with CFS in comparison with a control group of healthy volunteers and a group of patients with MDD.

PATIENTS AND METHODS

Twenty-five patients with CFS, 25 patients with major depressive disorder (MDD), and 25 healthy control subjects were given standardized tests of attention, working memory, and verbal and visual episodic memory, and were also tested for effects related to lack of effort/simulation, suggestibility, and fatigue.

RESULTS

Patients with CFS had slower phasic alertness, and also had impaired working, visual and verbal episodic memory compared to controls. They were, however, no more sensitive than the other groups to suggestibility or to fatigue induced during the cognitive session. Cognitive impairments in MDD patients were strongly associated with depression and subjective fatigue; in patients with CFS, there was a weaker correlation between cognition and depression (and no correlation with fatigue).

CONCLUSIONS

This study confirms the presence of an objective impairment in attention and memory in patients with CFS but with good mobilization of effort and without exaggerated suggestibility.

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.

Neuropsychological performance in persons with chronic fatigue syndrome: results from a population-based study

OBJECTIVE

To examine the neuropsychological function characterized in subjects with chronic fatigue syndrome (CFS) at the same time controlling for relevant confounding factors. CFS is associated with symptoms of neuropsychological dysfunction. Objective measures of neuropsychological performance have yielded inconsistent results possibly due to sample selection bias, diagnostic heterogeneity, comorbid psychiatric disorders, and medication usage.

METHOD

CFS subjects (n = 58) and well controls (n = 104) from a population-based sample were evaluated, using standardized symptom severity criteria. Subjects who had major psychiatric disorders or took medications known to influence cognition were excluded. Neuropsychological function was measured using the Cambridge Neuropsychological Test Automated Battery (CANTAB).

RESULTS

Compared with controls, CFS subjects exhibited significant decreases in motor speed as measured in the simple and five-choice movement segments of the CANTAB reaction time task. CFS subjects also exhibited alterations in working memory as manifested by a less efficient search strategy on the spatial working memory task, fewer % correct responses on the spatial recognition task, and prolonged latency to a correct response on the pattern recognition task. A significantly higher percentage of CFS subjects versus controls exhibited evidence of neuropsychological impairment (defined by performance 1 standard deviation below the CANTAB normative mean) in tasks of motor speed and spatial working memory. Impairment in CFS subjects versus control subjects ranged from 20% versus 4.8% in five-choice movement time (p = .002) to 27.8% versus 10.6% in search strategy on the spatial working memory task (p = .006).

CONCLUSIONS

These results confirm and quantify alterations in motor speed and working memory in CFS subjects independent of comorbid psychiatric disease and medication usage.

Diagnostic and treatment challenges of chronic fatigue syndrome: role of immediate-release methylphenidate

Chronic fatigue syndrome (CFS) is a distinct entity belonging to the group of persistent fatigue that can be challenging to diagnose and to treat. It is characterized by a combination of prolonged fatigue, other nonspecific somatic manifestations and neuropsychological symptoms, including difficulties with concentration, short-term memory and thinking, as well as impaired attention and slowed processing speed. Neurostimulants increasing dopamine and norepinephrine activity, such as bupropion, dextroamphetamine and recently immediate-release methylphenidate have been advocated to improve neurocognitive deficits. The use of immediate-release methylphenidate in CFS has been shown in one small study. Using the positive results of this study and the well-known beneficial effects of the drug on a range of similar cognitive symptoms in attention-deficit/hyperactivity disorder, this perspective addresses CFS and other related disorders and provides a discussion on the potential promising role of methylphenidate in the therapeutic armamentarium of CFS.

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.

Cognitive deficits in psychiatric disorders: Current status

Cognition denotes a relatively high level of processing of specific information including thinking, memory, perception, motivation, skilled movements and language. Cognitive psychology has become an important discipline in the research of a number of psychiatric disorders, ranging from severe psychotic illness such as schizophrenia to relatively benign, yet significantly disabling, non-psychotic illnesses such as somatoform disorder. Research in the area of neurocognition has started unlocking various secrets of psychiatric disorders, such as revealing the biological underpinnings, explaining the underlying psychopathology and issues related to course, outcome and treatment strategies. Such research has also attempted to uproot a number of previously held concepts, such as Kraepelin's dichotomy. Although the range of cognitive problems can be diverse, there are several cognitive domains, including executive function, attention and information processing, and working memory, which appear more frequently at risk. A broad range of impairment across and within the psychiatric disorders are highlighted in this oration. The oration summarizes the studies investigating cognitive processing in different psychiatric disorders. I will also discuss the findings of my own research on neurocognitive deficits in mood disorders, schizophrenia, obsessive-compulsive disorder, somatoform disorder, including studies on 'high-risk' individuals. Tracing the evaluation of neurocognitive science may provide new insights into the pathophysiology and treatment of psychiatric disorders.

Impaired cognitive performance in patients with chronic burnout syndrome

Chronic burnout refers to a syndrome caused by chronic stress. Clinical observations indicate that chronic burnout is associated with impaired cognitive functioning. However, there have been no systematic studies of the cognitive performance in chronic burnout patients. We have evaluated general cognitive ability, memory, and attention in 67 female patients treated for chronic burnout. The patients and 15 healthy control subjects were tested with standardized tests of verbal and nonverbal cognitive ability (WAIS), verbal (Claeson-Dahl) and nonverbal (Rey complex figures) memory, and visual and auditory attention (IVA). Significant reductions in nonverbal memory and auditory and visual attention were found for the patient group. These results indicate that patients with chronic burnout have specific cognitive impairments, which should be emphasized in the evaluation of symptoms and treatment regimes in this disorder.

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.

Cognitive Processing in Monozygotic Twins Discordant for Chronic Fatigue Syndrome

Twenty-one pairs of monozygotic twins discordant for chronic fatigue syndrome (CFS) and 21 matched healthy control (HC) subjects were assessed with 5 untimed tests and 5 timed tests from the computer-based NeuroCognitive Assessment Battery (R. K. Mahurin, 1993). Random effects regression showed no difference between CFS and healthy twins on any of the cognitive tests. Further, the twin groups did not differ from the HC group on any content-dependent measure. In contrast, both sets of twins performed worse than the HC group on all speed-dependent tests except Finger Tapping. Self-rated fatigue and dysphoric mood were only weakly correlated with cognitive performance. These data point toward a shared genetic trait related to information processing that is manifest in the CFS context. The findings have implications for differentiating genetic and acquired vulnerability in the symptomatic expression of the disorder. ((c) 2004 APA, all rights reserved)

Functional status, neuropsychological functioning, and mood in chronic fatigue syndrome (CFS): relationship to psychiatric disorder

Individuals with chronic fatigue syndrome (CFS) face chronic physical debilitation, reduced neuropsychological functioning, and changes in emotional well-being that significantly detract from quality of life. The role of psychiatric disturbance in reducing quality of life in CFS remains unclear. In the current investigation, the role of psychiatric status in reducing health-related quality of life in CFS was examined. Four subject groups were compared on measures of functional well-being, mood, and neuropsychological status: individuals with CFS and no history of psychiatric illness, individuals who had current symptoms of psychiatric illness that began after their CFS diagnosis, individuals who had current symptoms of psychiatric illness that began before their CFS diagnosis, and a healthy sedentary control group. Overall, it was found that individuals with CFS suffer from profound physical impairment. Concurrent psychiatric illness, however, did not adversely affect physical functional capacity. Physical functional capacity was not worse in individuals with a concurrent psychiatric illness. As expected, concurrent psychiatric illness was found to reduce emotional well-being. Moreover, individuals with a psychiatric illness that predated the onset of CFS suffered the greatest emotional distress. Thus, an individual's psychiatric history should be considered when attempting to understand the factors maintaining disability in CFS.

Chronic fatigue syndrome: probable pathogenesis and possible treatments

Chronic fatigue syndrome (CFS) belongs in the medically unexplained illnesses. It affects approximately 0.2-0.7% of the population in Western countries. It is characterised by unexplained fatigue, lasting 6 months or more, impairment of neurocognitive functions and quality of sleep, and of somatic symptoms, such as recurrent sore throat, muscle aches, arthralgias, headache and postexertional malaise. No link between infections and CFS has been clearly established but the immune system is activated, there are aberrations in several hypothalamic-pituitary axes and involvement of other parts of the central nervous system. No specific treatment has been found. Cognitive behavioural therapy is established to be of value to improve quality of life. More effective treatment should result, as advances in biomedical as well as psychological research continue.

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.

Chronic fatigue syndrome: neurological findings may be related to blood--brain barrier permeability

Despite volumes of international research, the etiology of chronic fatigue syndrome (CFS) remains elusive. There is, however, considerable evidence that CFS is a disorder involving the central nervous system (CNS). It is our hypothesis that altered permeability of the blood-brain barrier (BBB) may contribute to ongoing signs and symptoms found in CFS. To support this hypothesis we have examined agents that can increase the blood-brain barrier permeability (BBBP) and those that may be involved in CFS. The factors which can compromise the normal BBBP in CFS include viruses, cytokines, 5-hydroxytryptamine, peroxynitrite, nitric oxide, stress, glutathione depletion, essential fatty acid deficiency, and N-methyl-D-aspartate overactivity. It is possible that breakdown of normal BBBP leads to CNS cellular dysfunction and disruptions of neuronal transmission in CFS. Abnormal changes in BBBP have been linked to a number of disorders involving the CNS; based on review of the literature we conclude that the BBB integrity in CFS warrants investigation.

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.

The postconcussion syndrome after mild head trauma: is brain damage overdiagnosed? Part 1

Many investigators attribute the postconcussion syndrome following mild closed head injury to permanent brain damage. The evidence supporting this conclusion is reviewed, including the force necessary to cause permanent brain damage; the basis for determining whether the patient was exposed to sufficient force in the accident to permanently damage the brain; the basis for determining whether the patient actually has permanent brain damage (not just brain dysfunction) traceable to the accident; and whether the location and severity of brain damage is sufficient to account for the postconcussion syndrome.

CONCLUSION

the evidence for permanent traumatic brain damage as the cause of the postconcussion syndrome following mild closed head injury is weak.

Chronic fatigue syndrome: new insights and old ignorance

Chronic fatigue syndrome (CFS) is a condition characterized by impairment of neurocognitive functions and quality of sleep and of somatic symptoms such as recurrent sore throat, muscle aches, arthralgias, headache, and postexertional malaise. A majority of patients describe an infectious onset but the link between infections and CFS remains uncertain. Findings show an activation of the immune system, abberations in several hypothalamic-pituitary axes and involvement of other parts of the central nervous system. The origin is bound to be complex and it may well be that the solution will come together with a more generally altered view about mind-body dualism, and the concept of illness and disease.

Relation between neuropsychological impairment and functional disability in patients with chronic fatigue syndrome

OBJECTIVES

To examine the relation between neuropsychological impairment and functional disability in patients with chronic fatigue syndrome, and determine whether the relation is independent of psychiatric factors.

METHODS

The subjects were 53 patients with chronic fatigue syndrome and 32 healthy controls who did not exercise regularly. Subjects were administered a structured psychiatric interview and completed questionnaires focusing on depression and functional disability. They also completed a battery of standardised neuropsychological tasks focusing on the cognitive domains that patients with chronic fatigue syndrome experience as particularly difficult: memory (verbal and visual), and attention/concentration. A test score was defined as failing when it was > or =2 SD below the mean of the healthy controls after controlling for demographic factors.

RESULTS

Those patients with chronic fatigue syndrome with higher numbers of failing neuropsychological test scores reported significantly more days of general inactivity in the past month than those with fewer failing scores. This result remained significant even after partialling out the contribution of the presence of a comorbid axis I psychiatric episode and the overall level of depressive symptomology. Patients with failing verbal memory scores were particularly functionally disabled compared with those with passing scores.

CONCLUSION

A relation was found between cognitive impairment and functional disability which could not be explained entirely on the basis of psychiatric factors.

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.