Cognitive Disturbances in Chronic Fatigue Syndrome and Fibromyalgia
Question
Please comment on cognitive disturbances associated with chronic fatigue
syndrome (myalgic encephalomyelitis) and fibromyalgia syndrome.
Response
(from Neil M. Busis, MD, 04/27/2000)
There are 2 commonly accepted diagnostic criteria for chronic fatigue syndrome.
The first set,[1] from the Centers for Disease Control, do not include cognitive
dysfunction. These are:
Clinically evaluated, medically unexplained fatigue of at least 6 months' duration
that is of new onset, is not a result of ongoing exertion, is not substantially
alleviated by rest, and constitutes a substantial reduction in previous levels of
activity. In addition, these criteria demand that the patient have at least 4 of the
following symptoms:
- subjective memory impairment
- tender lymph nodes
- muscle pain
- joint pain
- headache
- unrefreshing sleep
- postexertional malaise lasting more than 24 hours.
However, the Oxford diagnostic criteria[2] include cognitive dysfunction as a core
feature of this syndrome. This scheme defines the syndrome as one of severe,
disabling fatigue of at least 6 months' duration that:
affects both physical and mental functioning, and
is present for more than 50% of the time. Other symptoms, particularly
myalgia and sleep and mood disturbance, may also be present.
Neuropsychological tests of patients with chronic fatigue syndrome support the
presence of reduced information processing speed and efficiency and suggest a
global non-modality-specific attentional dysfunction in these patients.[3]
The duration of symptoms relates to the degree of cognitive difficulties.[4]
Participants with long-duration chronic fatigue syndrome (median, 18 years; n =
258) reported a large number of specific cognitive difficulties that were greater in
severity than those reported by participants with short-duration chronic fatigue
syndrome (median, 3 years; n = 28).
Cognitive disturbances can also be seen in patients with fibromyalgia. For
example, Grace and colleagues[5] found that fibromyalgia patients performed more
poorly on tests of immediate and delayed recall and sustained auditory
concentration, and their ratings of both their memory abilities and sleep quality
were lower than those of controls. Perceived memory deficits of these patients
were disproportionately greater than their objective deficits. There were
significant correlations between performance on memory and concentration
measures and scores on questionnaires of pain severity and trait anxiety.
References:
1.Fukuda K, Straus S, Hickie I, Sharpe M, Dobbins J, Komaroff A. The
chronic fatigue syndrome: a comprehensive approach to its definition and
study. Ann Intern Med. 1994;121:953-959
2.Sharpe M, Archard LC, Banatvala JE. A report - chronic fatigue
syndrome: guidelines for research. J R Soc Med. 1991;84:118-121.
3.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;21:709-729
4.Friedberg F, Dechene L, McKenzie MJ II, Fontanetta R. Symptom
patterns in long-duration chronic fatigue syndrome. J Psychosom Res.
2000;48:59-68.
5.Grace GM, Nielson WR, Hopkins M, Berg MA. Concentration and
memory deficits in patients with fibromyalgia syndrome. J Clin Exp
Neuropsychol. 1999;21:477-487.
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