Category: Cognitive Dysfunction

Quality of attention in chronic fatigue syndrome: subjective reports of everyday attention and cognitive difficulty, and performance on tasks of focused attention

Abstract:

Patients with chronic fatigue syndrome (also known as post-viral fatigue syndrome or myalgic encephalomyelitis) commonly report cognitive difficulties concerning attention, concentration and memory. In this study, patients were compared with matched controls on two questionnaires which assess subjective difficulties with attention and general cognitive functioning, and on two tasks requiring focused attention.

Patients reported significantly greater difficulty with attention on the Everyday Attention Questionnaire and more cognitive symptoms on the Profile of Fatigue-Related Symptoms. The objective tests did not clearly indicate a deficit in patients’ focused attention; patients tended to perform less well on the Embedded Figures Test and the Stroop Colour-Word Interference Test, but these differences were not significant.

There was, however, evidence of psychomotor retardation, with patients having longer response times for word reading and colour naming in the Stroop test. Difficulties in interpreting findings for both subjective and objective cognitive measures are discussed.

 

Source: Ray C, Phillips L, Weir WR. Quality of attention in chronic fatigue syndrome: subjective reports of everyday attention and cognitive difficulty, and performance on tasks of focused attention. Br J Clin Psychol. 1993 Sep;32 ( Pt 3):357-64. http://www.ncbi.nlm.nih.gov/pubmed/8251968

 

Behavioural problems associated with the chronic fatigue syndrome

Abstract:

Disturbances of memory, concentration and motor function are often reported by patients with the chronic fatigue syndrome (CFS). The present study objectively evaluated these behavioural problems using a computerized test battery measuring memory, attention and motor skills.

Fifty-seven CFS patients were compared with 19 matched controls and all subjects completed the performance test battery and filled in questionnaires measuring psychopathology and mood. The patients reported significantly higher levels of depression, anxiety, physical symptoms and cognitive failures than the controls. Similarly, they reported more negative affect at the time of testing.

The patients were slower on psychomotor tasks, showed increased visual sensitivity and impaired attention. Digit span and free recall were not impaired but retrieval from semantic memory and logical reasoning were slower. None of the performance differences between patients and controls could be attributed to differences in psychopathology. These results agree with recent findings from other laboratories, and it is now time to consider the nature of the neurological dysfunction underlying these effects.

 

Source: Smith AP, Behan PO, Bell W, Millar K, Bakheit M. Behavioural problems associated with the chronic fatigue syndrome. Br J Psychol. 1993 Aug;84 ( Pt 3):411-23. http://www.ncbi.nlm.nih.gov/pubmed/8401992

 

Cognitive impairment in patients with chronic fatigue: a preliminary study

Erratum in: J Neurol Neurosurg Psychiatry 1993 Oct;56(10):1142

Abstract:

Subjective impairment of memory and concentration is a frequent complaint in sufferers from chronic fatigue. To study this, 65 general practice attenders identified as having chronic fatigue were administered a structured psychiatric interview and a brief screening battery of cognitive tests.

Subjective cognitive impairment was strongly related to psychiatric disorder, especially depressed mood, but not fatigue, anxiety, or objective performance. Simple tests of attention and concentration showed some impairment but this was influenced by both fatigue and depression.

Subjects with high levels of fatigue performed less well on a memory task requiring cognitive effort, even in the absence of depression. There was no evidence for mental fatiguability. The relationship between depression, fatigue, and cognitive function requires further research.

 

Source: McDonald E, Cope H, David A. Cognitive impairment in patients with chronic fatigue: a preliminary study. J Neurol Neurosurg Psychiatry. 1993 Jul;56(7):812-5. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1015065/ (Full article)

 

Analysis of neuropsychological functioning in patients with chronic fatigue syndrome

Abstract:

Memory impairment dominates the cognitive complaints of patients with chronic fatigue syndrome (CFS). Twenty CFS patients were available for studies with a clinical and experimental battery composed of memory and cognitive tests. The results on objective testing indicated that the CFS patients had some mild memory impairment, but only on tasks requiring conceptually driven encoding and retrieval processes. There were no associations between the nature of the precipitating illness, self ratings of fatigue, physical findings, or laboratory determination and objective memory performance or self report of memory functioning. These generally negative results indicate that memory impairment in CFS patients is typically mild and involves memory processes that participate in conceptualising information.

 

Source: Grafman J, Schwartz V, Dale JK, Scheffers M, Houser C, Straus SE. Analysis of neuropsychological functioning in patients with chronic fatigue syndrome. J Neurol Neurosurg Psychiatry. 1993 Jun;56(6):684-9. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC489620/ (Full article)

 

Memory deficits associated with chronic fatigue immune dysfunction syndrome

Abstract:

Performance on tests of memory in 39 patients who met Center for Disease Control (CDC) criteria for chronic fatigue immune dysfunction syndrome (CFIDS) was compared with 23 depressed patients (DSM-III-R) and 129 healthy controls.

Although the CFIDS patients had normal neuropsychological profiles, they significantly overestimated their ability (metamemory), performed significantly worse on tests of recall as context increased (e.g., recognition), made more errors when rehearsal was prevented, and had delayed mental scanning as memory load increased.

The overall pattern indicated that CFIDS patients had a significant memory deficit, far worse than implied by CDC criteria. The pattern for CFIDS patients was consistent with temporal-limbic dysfunction and significantly different than depressed patients and control subjects.

 

Source: Sandman CA, Barron JL, Nackoul K, Goldstein J, Fidler F. Memory deficits associated with chronic fatigue immune dysfunction syndrome. Biol Psychiatry. 1993 Apr 15-May 1;33(8-9):618-23. http://www.ncbi.nlm.nih.gov/pubmed/8329493

 

Information processing efficiency in chronic fatigue syndrome and multiple sclerosis

Abstract:

OBJECTIVE: To compare the cognitive performance of subjects with chronic fatigue syndrome (CFS), multiple sclerosis (MS), and healthy controls. All subjects were matched for age, education, and verbal intelligence, as previous neuropsychological studies of CFS had not used appropriate control groups.

DESIGN: Case-control design. All subjects were given a neuropsychological battery and the test scores were compared among the groups.

SETTING: Subjects with CFS and subjects with MS were recruited from private and institutional practice and from the community. Healthy subjects were recruited from the community.

PATIENTS/OTHER PARTICIPANTS: Twelve subjects (all female) with CFS participated in the study. Chronic fatigue syndrome was diagnosed in these patients in accordance with the requirements outlined by the Centers for Disease Control as modified subsequently to not exclude patients with concurrent depression and/or anxiety. All subjects with CFS were referred for a neuropsychological examination to assess persistent cognitive complaints. Eleven subjects (10 female, one male) with the diagnosis of clinically stable MS were chosen from clinics and the community because of complaints of mild to moderate cognitive impairment. The subjects with MS and 11 healthy volunteers (10 female, one male) were matched to the group with CFS by age, education, and estimated verbal intelligence (based on the Vocabulary subtest of the Wechsler Adult Intelligence Scale-Revised). The subjects with MS had a mean Kurtzke Expanded Disability Status Scale score of 4.95 (SD, 1.95; range, 2.0 to 7.5). As a result of the matching procedure, there were no differences among the three groups in age (F[2,31] = 0.32), education (F[2,31] = 0.80), and verbal intelligence (F[2,31] = 0.31).

INTERVENTIONS: None.

MAIN OUTCOME MEASURES: These measures included the Beck Depression Inventory (BDI), the Paced Auditory Serial Addition Test (PASAT), Digit Span Test, and the Similarities Test of Verbal Abstract Reasoning.

RESULTS: The mean number of correctly identified responses collapsed across the four PASAT trials was significantly different across groups (F[2,31] = 4.03; P < .05). While the CFS and MS groups did not differ from each other, subjects with CFS (SEM, 124.2 +/- 6.4) and subjects with MS (SEM, 112.9 +/- 10.9) scored significantly below controls (SEM, 146.4 +/- 6.4) (Fisher’s Protected Least Significant Difference test; P < .05). There were significant differences among the three groups on mean Digit Span Test performance (F[2,31] = 5.5; P < .01). While the CFS and MS group did not differ significantly from each other, only the CFS group was significantly lower than control (Fisher’s Protected Least Significant Difference test; P < .05). Mean performance on the Similarities test did not differ among the three groups (F = 0.58). In addition, there were significant differences among the three groups in mean BDI scores (F[2,31] = 7.6; P < .01). The CFS and MS groups did not differ significantly from each other, and both groups showed a statistically significantly elevated mean BDI score relative to the control group (Fisher’s Protected Least Significant Difference test; P < .05). No significant correlations were found between BDI scores and PASAT total scores (CFS, r = -.21; MS, r = .13; control, r = .27), or between BDI and Digit Span Test (CFS, r = -.32; MS, r = -.40; control, r = -.19). Results of the PASAT and Digit Span Test were significantly correlated in the CFS group (r = .71; P < .01), but not in the MS (r = .06) or control groups (r = .49).

CONCLUSIONS: These results indicate that subjects with CSF and subjects with MS show significant impairment on a test of complex concentration when compared with appropriate controls. The data suggest that subjects with CFS and subjects with MS have difficulty on tasks that require the simultaneous processing of complex cognitive information. Selective impairment in information processing efficiency may lie at the root of other cognitive complaints made by patients with CFS.

 

Source: DeLuca J, Johnson SK, Natelson BH. Information Processing Efficiency in Chronic Fatigue Syndrome and Multiple Sclerosis.Arch Neurol. 1993;50(3):301-304. doi:10.1001/archneur.1993.00540030065016. http://archneur.jamanetwork.com/article.aspx?articleid=592247

 

Neuropsychological and psychiatric abnormalities in myalgic encephalomyelitis: a preliminary report

Abstract:

Ten patients attending one general medical hospital clinic who fulfilled operational criteria for the diagnosis of myalgic encephalomyelitis (ME) and with a history longer than three months, underwent a series of standardized neuropsychological and psychiatric tests. Nine were able to complete the tests and were individually matched with a normal control group for age, sex, educational background and premorbid intelligence. The ME subjects showed inferior performance to the controls on two tests of verbal memory. Their personality scores displayed less extraversion and less psychoticism. This is the first report of objective neuropsychological abnormalities in patients with ME, suggesting a discrete deterioration of short-term memory. The findings may also suggest a concurrent psychiatric component of the condition, but the direction of causality remains to be clarified.

 

Source: Riccio M, Thompson C, Wilson B, Morgan DJ, Lant AF. Neuropsychological and psychiatric abnormalities in myalgic encephalomyelitis: a preliminary report. Br J Clin Psychol. 1992 Feb;31 ( Pt 1):111-20. http://www.ncbi.nlm.nih.gov/pubmed/1559114

 

Neurophysiology of postviral fatigue syndrome

Abstract:

The exact pathophysiology of excessive fatigue in patients with postviral fatigue syndrome (PVFS) remains uncertain in spite of increasing investigation. One objective abnormality of neuromuscular function is the increased jitter on single fibre EMG studies. While this is a sensitive technique which indicates a disturbance in the peripheral part of the motor unit, it is non-specific and its role in the pathophysiology remains unclear.

Impaired muscular activation with added force in response to superimposed electrical stimulation suggests an extra-muscular and/or central component of fatigue. Conventional neurophysiological studies and those of strength and endurance have shown no objective abnormality in patients compared with controls. The previous reports of disturbed muscle metabolism on NMR spectroscopy have not been confirmed in more recent studies and no consistent abnormality of excitation-contraction coupling has so far emerged.

Finally, unlike patients with depression, cognitive evoked potential studies suggest impaired attention, memory and stimulus evaluation in postviral fatigue syndrome. In future studies, the importance of utilising approved clinical criteria for patient inclusion cannot be overemphasized. Control groups should include sedentary or deconditioned as well as depressed subjects to help standardise these important variables.

 

Source: Jamal GA, Miller RG. Neurophysiology of postviral fatigue syndrome. Br Med Bull. 1991 Oct;47(4):815-25. http://www.ncbi.nlm.nih.gov/pubmed/1794086

 

Sensory and cognitive event-related potentials in myalgic encephalomyelitis

Abstract:

Myalgic Encephalomyelitis (ME) is a form of post viral fatigue syndrome resulting in myalgia and fluctuating fatiguability. Symptoms reflecting central nervous system dysfunction are common and include muscle weakness, headache, sensory disturbances, poor short term memory and impairment of concentration.

In view of the fact that sensory and cognitive disturbances are experienced by many patients objective evidence was sought with multi-modality sensory evoked potentials and auditory event-related cognitive potentials in a group of ME patients both with and without the enteroviral antigen, VP1 test positive.

The auditory brainstem, median nerve somatosensory and pattern reversal checkerboard visual potentials were normal for all 37 patients tested. In contrast to the sensory potentials significant differences in the mean latencies of the cognitive potential N2 and P3 were found. Reaction times were also significantly prolonged but the performance in terms of error was not significantly affected. No significant difference emerged in any of the parameters for the VP1 test. P3 was abnormal in latency or amplitude in 36% of the VP1 positive patients for the frequency discrimination task and 48% for the more difficult duration discrimination task.

The abnormalities indicate attentional deficits in some patients and slower speed of information processing in others. The prolonged latencies observed in these patients have not been observed in patients with depression in many other studies.

 

Source: Prasher D, Smith A, Findley L. Sensory and cognitive event-related potentials in myalgic encephalomyelitis. J Neurol Neurosurg Psychiatry. 1990 Mar;53(3):247-53. http://www.ncbi.nlm.nih.gov/pubmed/2324756

Note: You can read the full article here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1014138/

 

The neuropsychological dimensions of postinfectious neuromyasthenia (chronic fatigue syndrome): a preliminary report

Abstract:

Postinfectious neuromyasthenia (PIN) is a clinical syndrome of protracted and incomplete recovery after an apparent viral-like illness. Medical investigation yields few abnormalities which might account for the symptomatology. A substantial number of PIN patients complain of cognitive changes.

Specific complaints include impaired attention, concentration and abstraction skills. This study was designed to systematically investigate whether the aforementioned subjective complaints could be quantified objectively using standard neuropsychological instruments. Results indicated that on all tests but one, the subjects’ performances were significantly higher than those of their age matched groups in the normative data.

Specifically, PIN patients scored significantly better than their age matched norms on tests of concentration, attention and abstraction. What is most striking is the discrepancy between the subjective complaints of cognitive impairment and the objective results of the subjects’ performances on all tests.

These findings suggest that psychological factors may play an important role in the cognitive functioning of individuals diagnosed with postinfectious neuromyasthenia.

 

Source: Altay HT, Toner BB, Brooker H, Abbey SE, Salit IE, Garfinkel PE. The neuropsychological dimensions of postinfectious neuromyasthenia (chronic fatigue syndrome): a preliminary report. http://www.ncbi.nlm.nih.gov/pubmed/2394541