Category: Cognitive Dysfunction

Autoantibodies to a 68/48 kDa protein in chronic fatigue syndrome and primary fibromyalgia: a possible marker for hypersomnia and cognitive disorders

Abstract:

OBJECTIVE: To identify antinuclear antibodies (ANA) specific for chronic fatigue syndrome (CFS), and in related conditions such as fibromyalgia (FM) or psychiatric disorders.

METHODS: One hundred and fourteen CFS patients and 125 primary and secondary FM patients were selected based on criteria advocated by the Centers for Disease Control and Prevention and by the American College of Rheumatology, respectively. As controls, healthy subjects and patients with either various psychiatric disorders or diffuse connective tissue diseases were included. Autoantibodies were examined by immunoblot utilizing HeLa cell extracts as the antigen.

RESULTS: Autoantibodies to a 68/48 kDa protein were present in 13.2 and 15.6% of patients with CFS and primary FM, respectively. In addition, autoantibodies to a 45 kDa protein were found in 37.1 and 21.6% of the patients with secondary FM and psychiatric disorders, respectively. Meanwhile, these two autoantibodies were not found at all in connective tissue disease patients without FM, nor in healthy subjects (P<0.05). As a group, the anti-68/48 kDa-positive CFS patients presented more frequently with hypersomnia (P<0.005), short-term amnesia (P<0.07) or difficulty in concentration (P<0.05) than those CFS patients without the antibodies.

CONCLUSIONS: The presence of the anti-68/48 kDa protein antibodies in a portion of both CFS and primary FM patients suggests the existence of a common immunological background. These antibodies may find utility as possible markers for a clinicoserological subset of CFS/FM patients with hypersomnia and cognitive complaints.

 

Source: Nishikai M, Tomomatsu S, Hankins RW, Takagi S, Miyachi K, Kosaka S, Akiya K. Autoantibodies to a 68/48 kDa protein in chronic fatigue syndrome and primary fibromyalgia: a possible marker for hypersomnia and cognitive disorders. Rheumatology (Oxford). 2001 Jul;40(7):806-10. http://rheumatology.oxfordjournals.org/content/40/7/806.long (Full article)

 

Divided attention deficits in patients with chronic fatigue syndrome

Abstract:

Chronic fatigue syndrome (CFS) patients and controls were compared on a variety of mood state, personality, and neuropsychological measures, including memory, word finding, and attentional tasks that required participants to focus, sustain, or divide their attention, or to perform a combination of these functions.

CFS patients demonstrated a selective deficit on 3 measures of divided attention. Their performance on the other neuropsychological tests of intelligence, fluency, and memory was no different than that of normal controls despite their reports of generally diminished cognitive capacity. There was an inverse relation between CFS patient fatigue severity and performance on 1 of the divided attention measures.

Given these findings, it is probable that CFS patients will report more cognitive difficulties in real-life situations that cause them to divide their effort or rapidly reallocate cognitive resources between 2 response channels (vision and audition).

 

Source: Ross S, Fantie B, Straus SF, Grafman J. Divided attention deficits in patients with chronic fatigue syndrome. Appl Neuropsychol. 2001;8(1):4-11. http://www.ncbi.nlm.nih.gov/pubmed/11388122

 

Neuropsychological function in patients with chronic fatigue syndrome, multiple sclerosis, and depression

Abstract:

Patients with chronic fatigue syndrome (CFS), multiple sclerosis (MS), and major depression were compared with controls and with each other on a neuropsychological battery that included standard neuropsychological tests and a computerized set of tasks that spanned the same areas of ability.

A total of 101 participants were examined, including 29 participants with CFS, 24 with MS, 23 with major depressive disorder, and 25 healthy controls. There were significant differences among the groups in 3 out of 5 cognitive domains: memory, language, and spatial ability. Assessment of psychiatric symptoms indicated that all 3 patient groups had a higher prevalence of depression than the controls. A total measure of psychiatric symptomatology also differentiated the patients from the controls.

After covarying the cognitive test scores by a measure of depression, the patient groups continued to differ from controls primarily in the area of memory. The findings support the view that the cognitive deficits found in CFS cannot be attributed solely to the presence of depressive symptomatology in the patients.

 

Source: Daly E, Komaroff AL, Bloomingdale K, Wilson S, Albert MS. Neuropsychological function in patients with chronic fatigue syndrome, multiple sclerosis, and depression. Appl Neuropsychol. 2001;8(1):12-22. http://www.ncbi.nlm.nih.gov/pubmed/11388119

 

Working memory deficits associated with chronic fatigue syndrome

Abstract:

Cognitive impairments are among the most frequently reported and least investigated components of the chronic fatigue syndrome (CFS). As part of a multifaceted study of the CFS, the present study investigated the cognitive functioning of chronic fatigue patients.

The performance of 20 CFS patients was compared to that of controls (N = 20) on 4 tests of working memory (WM). Digit Span Forward was used to assess the storage capacity of WM. Multiple aspects of central executive functioning were assessed using several standard measures: Digit Span Backward, and Trails A and Trails B. More recently developed measures of WM were used to assess control of processing under temporal demands (working memory task) and resistance to interference (a sustained attention task).

Deficits were restricted to more demanding tasks, requiring resistance to interference and efficient switching between processing routines. The overall results clearly implicate deficits in the control aspects of central executive function in CFS.

 

Source: Dobbs BM, Dobbs AR, Kiss I. Working memory deficits associated with chronic fatigue syndrome. J Int Neuropsychol Soc. 2001 Mar;7(3):285-93. http://www.ncbi.nlm.nih.gov/pubmed/11311029

 

Neuropsychological functioning in chronic fatigue syndrome: a review

Abstract:

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 scientifically 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 inconsistencies 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.

 

Source: Michiels V, Cluydts R. Neuropsychological functioning in chronic fatigue syndrome: a review. Acta Psychiatr Scand. 2001 Feb;103(2):84-93. http://www.ncbi.nlm.nih.gov/pubmed/11167310

 

Abnormal neuropsychological findings are not necessarily a sign of cerebral impairment: a matched comparison between chronic fatigue syndrome and multiple sclerosis

Abstract:

OBJECTIVE: The aim of this study was to assess the potential impact of effort in comparative studies assessing neurocognitive dysfunction in patients with and without a neurologic diagnosis.

BACKGROUND: It was hypothesized that a subgroup within a group of patients with prominent neurocognitive complaints but without a neurologic diagnosis would have impaired performance on a task originally designed to detect malingering.

METHOD: We compared the neuropsychological performance of a group of 40 patients with a definite diagnosis of multiple sclerosis (MS) with that of 67 patients with chronic fatigue syndrome (CFS). The Amsterdam Short-Term Memory Test, a forced-choice memory task, served as measure to detect submaximal effort. In addition, we administered a regular neuropsychological task generally considered to be sensitive for cognitive deterioration.

RESULTS: Compared with the MS group (13%), a larger proportion of the matched CFS group (30%) obtained scores indicative of reduced effort. In contrast, the proportions of patients scoring below the cutoff value on a conventional neuropsychological test did not differ significantly (17% of MS patients and 16% of CFS patients).

CONCLUSIONS: The results obtained raise the question of to what extent abnormal test findings in the absence of documented neurologic impairment should be interpreted as a sign of cerebral impairment. The suggestion has been made to screen more often for biased results in comparative research studies so as to enhance valid interpretation of neuropsychological findings.

 

Source: van der Werf SP, Prins JB, Jongen PJ, van der Meer JW, Bleijenberg G. Abnormal neuropsychological findings are not necessarily a sign of cerebral impairment: a matched comparison between chronic fatigue syndrome and multiple sclerosis. Neuropsychiatry Neuropsychol Behav Neurol. 2000 Jul;13(3):199-203. http://www.ncbi.nlm.nih.gov/pubmed/10910092

 

The difference in patterns of motor and cognitive function in chronic fatigue syndrome and severe depressive illness

Abstract:

BACKGROUND: Chronic fatigue syndrome (CFS) and major depressive disorder (MDD) share many symptoms and aetiological factors but may have different neurobiological underpinnings. We wished to determine the profile of the biological variables disturbed in CFS and MDD, and identify any critical factors that differentiate the disorders.

METHODS: Thirty patients with CFS, 20 with MDD and 15 healthy controls matched group-wise for age and sex were recruited. Subjects were given a detailed battery of motor and cognitive tests, including measures of psychomotor speed, memory and maximal voluntary muscle contraction in both the morning and evening that were balanced to avoid order effects.

RESULTS: CFS patients generally performed worse on cognitive tests than healthy controls, but better than patients with MDD. Both patient groups had markedly impaired motor function compared with healthy controls. MDD subjects showed a significantly greater diurnal improvement in maximal voluntary contraction than healthy controls.

CONCLUSIONS: Patients with CFS and MDD show similarly substantial motor impairment, but cognitive deficits are generally more marked in MDD. Diurnal changes in some functions in MDD may differentiate the disorder from CFS.

 

Source: Lawrie SM, MacHale SM, Cavanagh JT, O’Carroll RE, Goodwin GM. The difference in patterns of motor and cognitive function in chronic fatigue syndrome and severe depressive illness. Psychol Med. 2000 Mar;30(2):433-42. http://www.ncbi.nlm.nih.gov/pubmed/10824663

 

Attention and information processing efficiency in patients with Chronic Fatigue Syndrome

Abstract:

In this study a battery of attentional tests and a verbal memory task were administered to outpatients with Chronic Fatigue Syndrome (CFS) in order to evaluate aspects of attention that have not been explored in this group to date. In addition, this study was designed to further examine memory function and to extend the few reports investigating the rate of cognitive processing independent of motor speed and the possibility of a modality-specific impairment of information processing.

Twenty-nine patients with CFS and 22 healthy controls matched for age, gender, intelligence, and education were included in this study. The results show that patients with CFS do not seem to be impaired for modification of phasic arousal level, nor for visual selective attention requiring shifting of attention in the visuospatial field.

The results further support the presence of reduced information processing speed and efficiency, and strengthen the evidence of a global non-modality-specific attentional dysfunction in patients with CFS. In this study the poor performance of patients with CFS on recall of verbal information was due to poor initial storage rather than to a retrieval failure.

 

Source: Michiels V, de Gucht V, Cluydts R, Fischler B. Attention and information processing efficiency in patients with Chronic Fatigue Syndrome. J Clin Exp Neuropsychol. 1999 Oct;21(5):709-29. http://www.ncbi.nlm.nih.gov/pubmed/10572289

 

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

Abstract:

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.

 

Source: LaManca JJ, Sisto SA, DeLuca J, Johnson SK, Lange G, Pareja J, Cook S, Natelson BH. Influence of exhaustive treadmill exercise on cognitive functioning in chronic fatigue syndrome. Am J Med. 1998 Sep 28;105(3A):59S-65S. http://www.ncbi.nlm.nih.gov/pubmed/9790484

 

Evaluating neuropsychological impairment in chronic fatigue syndrome

Abstract:

This study was designed to provide an estimate of the prevalence of neuropsychological impairment in chronic fatigue syndrome (CFS), to evaluate the concordance between impairment found on standardized tests and self-reported neuropsychological problems, and to study the relationship between neuropsychological functioning and fatigue severity and psychological processes.

We adopted an individual approach to determine neuropsychological impairment as contrasted with the group-comparisons approach used in previous studies. Also, correction for premorbid functioning and confounders was done on an individual basis.

The results show that a minority of participants were impaired in neuropsychological functioning. There was no relationship between neuropsychological impairment on standardized tests and self-reported memory and concentration problems. Neuropsychological functioning was not related to fatigue or depression. Slowed speed of information processing and motor speed were related to low levels of physical activity.

 

Source: Vercoulen JH, Bazelmans E, Swanink CM, Galama JM, Fennis JF, van der Meer JW, Bleijenberg G. Evaluating neuropsychological impairment in chronic fatigue syndrome. J Clin Exp Neuropsychol. 1998 Apr;20(2):144-56. http://www.ncbi.nlm.nih.gov/pubmed/9777468