Category: Cognitive Dysfunction

Neuropsychological deficits in patients with chronic fatigue syndrome

Abstract:

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.

 

Source: Busichio K, Tiersky LA, Deluca J, Natelson BH. Neuropsychological deficits in patients with chronic fatigue syndrome. J Int Neuropsychol Soc. 2004 Mar;10(2):278-85. http://www.ncbi.nlm.nih.gov/pubmed/15012848

 

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

Abstract:

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.

 

Source: Deluca J, Christodoulou C, Diamond BJ, Rosenstein ED, Kramer N, Natelson BH. Working memory deficits in chronic fatigue syndrome: differentiating between speed and accuracy of information processing. J Int Neuropsychol Soc. 2004 Jan;10(1):101-9. http://www.ncbi.nlm.nih.gov/pubmed/14751012

 

Examining the influence of biological and psychological factors on cognitive performance in chronic fatigue syndrome: a randomized, double-blind, placebo-controlled, crossover study

Abstract:

The pathophysiology of chronic fatigue syndrome (CFS) remains unclear; however, both biological and psychological factors have been implicated in establishing or maintaining this condition. People with CFS report significant and disabling cognitive difficulties such as impaired concentration that in some cases are exacerbated by exposure to chemical triggers. The aim of this study was to determine if neuropsychological deficits in CFS are triggered by exposure to chemicals, or perceptions about the properties of these substances.

Participants were 36 people with a primary diagnosis of CFS, defined according to Centers for Disease Control (CDC) criteria. A randomized, double-blind, placebo-controlled, crossover design was used, with objective assessment of neuropsychological function and participant rating of substance type, before and after exposure to placebo or chemical trigger. Results showed decrements in neuropsychological tests scores on three out of four outcome measures when participants rated the substance they had been exposed to as “chemical.” No change in performance was found based on actual substance type.

These results suggest that cognitive attributions about exposure substances in people with CFS may be associated with worse performance on neuropsychological tasks. In addition, these findings suggest that psychological interventions aimed at modifying substance-related cognitions may reduce some symptoms of CFS.

 

Source: Smith S, Sullivan K. Examining the influence of biological and psychological factors on cognitive performance in chronic fatigue syndrome: a randomized, double-blind, placebo-controlled, crossover study. Int J Behav Med. 2003;10(2):162-73. http://www.ncbi.nlm.nih.gov/pubmed/12763708

 

Validation of a telephone cognitive assessment test battery for use in chronic fatigue syndrome

Abstract:

We compared a computerized version of the Cognitive Drug Research (CDR) cognitive assessment test battery and a completely automated telephone version of the same battery. These assessed aspects of attention, working memory and long-term memory. Both methods were used to assess the cognitive performance of a cohort of 30 people with confirmed chronic fatigue syndrome (CFS) and a group of 30 healthy controls matched for age and education.

The CFS group had significantly slower reaction times on all four cognitive measures on both the computerized and telephone tests. The mood data followed similar patterns in the computer and telephone assessments. The results from both forms of the test battery confirmed the pattern and severity of cognitive impairment in CFS. Furthermore, the two methods of testing were similarly sensitive in detecting cognitive deficits. The incapacitating nature of CFS may cause problems for researchers if the restrictions to mobility affect the representativeness of the study group. The findings of the present study support the use of a fully automated telephone cognitive testing system for detecting deficits in CFS.

 

Source: McCue P, Scholey AB, Herman C, Wesnes KA. Validation of a telephone cognitive assessment test battery for use in chronic fatigue syndrome.  J Telemed Telecare. 2002;8(6):337-43. http://www.ncbi.nlm.nih.gov/pubmed/12537921

 

Relationship between chronic fatigue and subjective symptoms of fatigue with performance status (P.S.) and subjective fatigue scale for young adults (SFS-Y)

Abstract:

OBJECTIVE: Today, fatigue complaints in adolescence are regarded as an issue for young adults as they may progress to the chronic fatigue syndrome. The purpose of this study was to examine the relationships between chronic fatigue based on self-reported performance states (P.S.) and subjective symptoms of fatigue assessed with a fatigue scale for young adults (SFS-Y).

METHOD: The SFS-Y consisted of 24 item questions represonting 6 sub-scales, for difficulty in concentrated thinking, languor, reduced activation, reduced motivation, drowsiness and feeling of physical disintegration. The SFS-Y and for assessing fatigue symptoms and P.S. for chronic fatigue were administered to 548 male and female students aged 15-18 yr and to 608 male students aged 16-18 yr, respectively. Discriminant analysis and a logistic analysis model were employed to define the relevance of subjective symptoms of fatigue to chronic fatigue.

RESULTS: It was determined that the SFS-Y can discliminate P.S. with high probability (74.0-81.4%), with accuracy beyond a fixed level. In particular, the correlation with “difficulty in concentrated thinking” was high.

CONCLUSION: It was judged that the SFS-Y is effective as an index for discrimination of chronic fatigue in young adults with a particularly high relationship between “difficulty in centrated thinking” and chronic fatigue.

 

Source: Kobayashi H, Demura S. Relationship between chronic fatigue and subjective symptoms of fatigue with performance status (P.S.) and subjective fatigue scale for young adults (SFS-Y). Nihon Koshu Eisei Zasshi. 2002 Oct;49(10):1062-9. [Article in Japanese] http://www.ncbi.nlm.nih.gov/pubmed/12462040

 

Immunological variables mediate cognitive dysfunction in gulf war veterans but not civilians with chronic fatigue syndrome

Abstract:

We explored the relationship between a set of immunological variables and a set of cognitive and functional status measures and a diagnosis of chronic fatigue syndrome (CFS) in civilians and veterans using various regression and factor analytic methods.

Our approach emphasized the extraction of a few distinct factors in order to limit statistical problems associated with doing large numbers of multiple comparisons. This approach led to our finding cytokine data grouping into type 1 and type 2 clusters. A type 2 cluster plus a T and B cell factor predicted CFS caseness for Gulf War veterans but not for civilians with CFS. When a cognitive variable, reaction time, was added into the model, both immunological factors lost statistical significance; this indicates that the cognitive variable reaction time moderated the effects of the immunological factors in predicting patient status.

We did a similar analysis on the roles of the immunological and cognitive variables in functional status using SF-36 data. Higher levels of these same two immunological factors predicted poorer general health as well as poorer physical and social functioning in Gulf War veterans but not in civilians with CFS. When the reaction time factor was added, only the lymphocyte factor remained significant. This implies that lymphocytes are directly related to functional status in Gulf War veterans with CFS, but the Th2 factor produces its effect on functional status via changes in cognitive abilities.

Copyright 2002 S. Karger AG, Basel

 

Source: Brimacombe M, Zhang Q, Lange G, Natelson B. Immunological variables mediate cognitive dysfunction in gulf war veterans but not civilians with chronic fatigue syndrome. Neuroimmunomodulation. 2002-2003;10(2):93-100. http://www.ncbi.nlm.nih.gov/pubmed/12372983

 

Using an interleukin-6 challenge to evaluate neuropsychological performance in chronic fatigue syndrome

Abstract:

BACKGROUND: Individuals with acute infections experience a range of symptoms including fatigue, malaise, muscle aches, and difficulties with concentration and memory that are usually self-limited. This cluster of symptoms is otherwise, similar to those that characterize chronic fatigue syndrome (CFS). The goal of the present study was to evaluate the cognitive and psychological functioning of CFS patients and normal controls (NCs) when they both were experiencing acute influenza-like symptoms. To induce influenza-like symptoms, we administered interleukin-6 (IL-6), a cytokine that temporarily activates the acute phase immunological and endocrine responses.

METHODS: Nineteen patients who met the 1994 International CFS Study Group Criteria and ten normal controls (NCs) completed routine clinical evaluations, neuropsychological tests of short-term memory, selective attention, and executive control, and self-ratings of somatic symptoms and psychological mood before, shortly following, and 1 day after IL-6 administration.

RESULTS: CFS patients consistently reported more somatic symptoms, even when both groups perceived that they were ill. Both groups somatic symptoms increased during the IL-6 challenge, but the CFS patients symptoms increased more rapidly than controls. In general, the CFS patients performed similarly to NCs on the cognitive measures before, during, and after the IL-6. In contrast to predictions, IL-6 provocation did not impair the cognitive performance of either CFS patients or NCs.

CONCLUSIONS: The IL-6 provocation exacerbated the patients self-reported symptoms but did not reveal notable cognitive impairments between patients and controls during cytokine-induced acute influenza-like symptoms.

 

Source: Arnold MC, Papanicolaou DA, O’Grady JA, Lotsikas A, Dale JK, Straus SE, Grafman J. Using an interleukin-6 challenge to evaluate neuropsychological performance in chronic fatigue syndrome. Psychol Med. 2002 Aug;32(6):1075-89. http://www.ncbi.nlm.nih.gov/pubmed/12214788

 

Neuropsychological performance and noradrenaline function in chronic fatigue syndrome under conditions of high arousal

Abstract:

RATIONALE: Subjective and objective impairments in neuropsychological function have been reported in chronic fatigue syndrome (CFS) patients under conditions of high arousal. These impairments may reflect impaired central noradrenaline function such as impaired post-synaptic alpha-2 adrenoceptor function.

OBJECTIVES: To determine whether high-dose clonidine has greater agonist effects at central post-synaptic alpha-2 receptors in CFS patients than controls under conditions of high arousal. As a result clonidine may reverse neuropsychological deficits underlying symptoms of poor concentration and memory.

METHODS: High-dose clonidine (2.5 mg/kg) and placebo challenge tests were given in random order to ten medication-free CFS patients without anxiety disorders, depressive disorders or migraine and ten matched healthy controls under the same stressors (timed neuropsychological testing, venous sampling, intravenous drug administration). Growth hormone, cortisol, blood pressure, pulse rate, visual analogue scales of subjective neuropsychological performance and the performance on several tests from a computerised neuropsychological battery were measured.

RESULTS: In CFS patients versus controls, clonidine enhanced both growth hormone ( P = 0.028) and cortisol release ( P = 0.021) and increased speed in the initial stage of a planning task ( P = 0.023). There were no other differences between CFS patients and controls on hormonal, physiological, symptomatic or neuropsychological measures.

CONCLUSIONS: Under conditions of high arousal, CFS patients may display supersensitive central post-synaptic alpha-2 adrenoceptor function associated with the release of cortisol and growth hormone and initial thinking time in planning tasks.

 

Source: Morriss RK, Robson MJ, Deakin JF. Neuropsychological performance and noradrenaline function in chronic fatigue syndrome under conditions of high arousal. Psychopharmacology (Berl). 2002 Sep;163(2):166-73. Epub 2002 Jul 30. http://www.ncbi.nlm.nih.gov/pubmed/12202963

 

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

Abstract:

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.

 

Source: Short K, McCabe M, Tooley G. Cognitive functioning in chronic fatigue syndrome and the role of depression, anxiety, and fatigue. J Psychosom Res. 2002 Jun;52(6):475-83. http://www.ncbi.nlm.nih.gov/pubmed/12069872

 

Perception of cognitive performance in patients with chronic fatigue syndrome

Abstract:

This study examined discrepancies between perceived and actual performance by patients with chronic fatigue syndrome (CFS) confronted with a challenging cognitive task. Before and after completing a modified version of the Stroop task, 40 patients and 40 healthy control participants estimated their own performance and the performance that would normally be achieved by someone of equal age and education level. After correcting for differences between the groups in depression, we found no differences in actual performance on the Stroop. However, patients with CFS consistently underestimated their performance relative to normal performance. This difference was observed for both depressed and nondepressed subgroups of patients, persisted after adjusting the results for depression, and correlated with patients’ ratings of the mental effort and fatigue evoked by the task. The results are discussed in light of cognitive models of CFS that suggest the setting of impossibly high standards of personal performance may contribute to the dynamism of this disease.

 

Source: Metzger FA, Denney DR. Perception of cognitive performance in patients with chronic fatigue syndrome. Ann Behav Med. 2002 Spring;24(2):106-12. http://www.ncbi.nlm.nih.gov/pubmed/12054315