Epidemiologic advances in chronic fatigue syndrome

Abstract:

Epidemiologic studies of chronic fatigue syndrome (CFS) have been hampered by the absence of a specific diagnostic test, but with increasing interest in this disorder there has been a greater understanding of the risk factors, illness patterns, and other aspects of this multisystem disorder.

Working case definitions have been developed for research purposes but they have continued to change over time and have not always been utilized precisely by various investigators. This has been a major factor in the widely varying estimates of prevalence rates, but two different studies using the same working definition and including a medical work-up have estimated the prevalence to be approximately 200/100,000. Clusters of CFS cases, which appear to be related to earlier reports of “epidemic neuromyasthenia”, have attracted considerable attention and appear to be well documented, although investigated with varying methodology and often with dissimilar case definitions.

Risk factors for cases occurring in clusters and sporadically appear to be similar, the most consistent ones being female gender and the co-existence of some form of stress, either physical or psychological. The prognosis of CFS is difficult to predict, although cases occurring as part of clusters appear to have a better prognosis as a group than sporadic cases, and those with an acute onset have a better prognosis than those with gradual onset.

It is highly unlikely that there is a single agent, infectious or noninfectious, that is responsible for more than a small proportion of CFS cases and, at the present time, the risk factors for developing CFS appear to lie more prominently in the host rather than the environment.

 

Source: Levine PH. Epidemiologic advances in chronic fatigue syndrome. J Psychiatr Res. 1997 Jan-Feb;31(1):7-18. http://www.ncbi.nlm.nih.gov/pubmed/9201643

 

Detection of RNA sequences in cultures of a stealth virus isolated from the cerebrospinal fluid of a health care worker with chronic fatigue syndrome. Case report

Abstract:

A cytopathic stealth virus was cultured from the cerebrospinal fluid of a nurse with chronic fatigue syndrome. Reverse transcriptase-polymerase chain reaction (RT-PCR) performed on the patient’s culture yielded positive results with primer sets based on sequences of a previously isolated African green monkey simian-cytomegalovirus-derived stealth virus. The same primer sets did not yield PCR products when tested directly on DNA extracted from the cultures. The findings lend support to the possibility of replicative RNA forms of certain stealth viruses and have important implications concerning the choice of therapy in this type of patient.

 

Source: Martin WJ. Detection of RNA sequences in cultures of a stealth virus isolated from the cerebrospinal fluid of a health care worker with chronic fatigue syndrome. Case report. Pathobiology. 1997;65(1):57-60. http://www.ncbi.nlm.nih.gov/pubmed/9200191

 

An open study of the efficacy and adverse effects of moclobemide in patients with the chronic fatigue syndrome

Abstract:

There is a strong association between the chronic fatigue syndrome and both depressive illness and sleep disturbance, but the efficacy of antidepressants is uncertain. We studied the efficacy and adverse effects of moclobemide in patients with chronic fatigue syndrome, stratifying the sample both by co-morbid major depressive illness and by sleep disturbance.

Forty-nine patients with chronic fatigue syndrome were recruited. Patients were given moclobemide up to 600 mg a day for 6 weeks. Four (8%) patients dropped out, three because of adverse effects. Adverse effects were otherwise mild and transient. On analysing the whole sample, there were significant but small reductions in fatigue, depression, anxiety and somatic amplification, as well as a modest overall improvement.

The greatest improvement occurred in those individuals who had a co-morbid major depressive illness, with seven out of 14 (50%) of such individuals rating themselves as “much better” by 6 weeks, compared to six out of 31 (19%) of those who were not depressed (31% difference, 95% CI 1-60%, P = 0.04). Sleep disturbance had no effect on outcome.

Moclobemide may be indicated in patients with chronic fatigue syndrome and a co-morbid major depressive disorder. A randomized, placebo-controlled trial is needed to confirm this. These results do not support moclobemide as an effective treatment of chronic fatigue syndrome in the absence of a major depressive disorder.

 

Source: White PD, Cleary KJ. An open study of the efficacy and adverse effects of moclobemide in patients with the chronic fatigue syndrome. Int Clin Psychopharmacol. 1997 Jan;12(1):47-52. http://www.ncbi.nlm.nih.gov/pubmed/9179634

 

Sleep anomalies in the chronic fatigue syndrome. A comorbidity study

Abstract:

Polysomnographic findings were compared between a group of patients with the chronic fatigue syndrome (CFS; n = 49) and a matched healthy control (HC) group (n = 20).

Sleep initiation and sleep maintenance disturbances were observed in the CFS group. The percentage of stage 4 was significantly lower in the CFS group. A discriminant analysis allowed a high level of correct classification of CFS subjects and HC. Sleep-onset latency and the number of stage shifts/hour contributed significantly to the discriminant function.

The presence of these anomalies as well as the decrease in stage 4 sleep were not limited to the patients also diagnosed with fibromyalgia or with a psychiatric disorder. No association was found between sleep disorders and the degree of functional status impairment. The mean REM latency and the percentage of subjects with a shortened REM latency were similar in CFS and HC.

 

Source: Fischler B, Le Bon O, Hoffmann G, Cluydts R, Kaufman L, De Meirleir K. Sleep anomalies in the chronic fatigue syndrome. A comorbidity study. Neuropsychobiology. 1997;35(3):115-22. http://www.ncbi.nlm.nih.gov/pubmed/9170115

 

Cognitive performance and complaints of cognitive impairment in chronic fatigue syndrome (CFS)

Abstract:

Patients with chronic fatigue syndrome (CFS) complain that they have difficulties with concentration and memory but studies to date have not found consistent objective evidence of performance deficits.

Two groups of CFS patients, depressed and non-depressed, and healthy controls, were asked about concentration problems in general and specifically when reading. CFS subjects were more likely than controls to report that they had concentration problems when reading, that they needed to re-read text and that they failed to take in what they were reading.

Subjects then performed a task in which their reading behaviour and text recall was measured. While all CFS subjects complained of general cognitive failures and of difficulties with reading, only depressed CFS subjects recalled significantly less of the text than controls. Severity of complaints about reading problems was not related to amount of text recalled, but was related to severity of depressed mood. However, subjects were able to evaluate accurately their ability to remember the text immediately after reading it and before being tested for recall.

Additionally, subjects performed a paired-associate learning task on which no significant differences between the subject groups was found. It is concluded that deficits in cognitive functioning in CFS patients are more likely to be found on naturalistic than on laboratory tasks.

 

Source: Wearden A, Appleby L. Cognitive performance and complaints of cognitive impairment in chronic fatigue syndrome (CFS). Psychol Med. 1997 Jan;27(1):81-90. http://www.ncbi.nlm.nih.gov/pubmed/9122311

 

Neuropsychological and psychological functioning in chronic fatigue syndrome

Abstract:

Although patients with chronic fatigue syndrome (CFS) typically present subjective complaints of cognitive and psychological difficulties, studies to date have provided mixed objective support for the existence of specific cognitive deficits. The present study was designed to examine differences in performance between individuals diagnosed with CFS and matched controls with respect to sustained attention, processing efficiency, learning, and memory.

Subjects included 17 patients meeting Centers for Disease Control research criteria for CFS and 17 control subjects. Subjects were administered six measures assessing attention, memory, and word-finding ability and two measures assessing psychological distress.

For the most part, the two groups did not differ on measures of neurocognitive functioning. Significant group differences were found on a single measure of attention and incidental memory. However, CFS patients differed markedly from controls with respect to reported psychological distress.

The results support previous findings of notable levels of psychological distress among CFS patients. They also suggest the need for alternative research paradigms to assess the cognitive abilities of CFS patients.

 

Source: Kane RL, Gantz NM, DiPino RK. Neuropsychological and psychological functioning in chronic fatigue syndrome. Neuropsychiatry Neuropsychol Behav Neurol. 1997 Jan;10(1):25-31. http://www.ncbi.nlm.nih.gov/pubmed/9118194

 

Screening for psychiatric disorders in chronic fatigue and chronic fatigue syndrome

Abstract:

Psychiatric disorders are common in chronic fatigue (CF) and chronic fatigue syndrome (CFS). To determine the usefulness of the General Health Questionnaire (GHQ), a self-report measure of psychological distress, in identifying those with psychiatric illnesses, a structured psychiatric interview and the GHQ were administered to 120 CF and 161 CFS patients seen in a referral clinic.

Overall, 87 (35%) patients had a current and 210 (82%) a lifetime psychiatric disorder. Compared to patients without psychiatric disorders, GHQ scores above the threshold (> or = 12) were more frequent among patients with current (p < 0.001) and lifetime (p < 0.05) diagnoses; scores among patients with CF and CFS were similar.

Longer illness duration, greater fatigue severity, and current psychiatric disorders were significant predictors of the GHQ score. In CF and CFS, the best sensitivity (0.69-0.76) and specificity (0.51-0.62) were achieved for current psychiatric diagnoses using a threshold score of > or = 12. Thus, patients scoring < 12 on the GHQ are significantly less likely to have a psychiatric disorder.

 

Source: Buchwald D, Pearlman T, Kith P, Katon W, Schmaling K. Screening for psychiatric disorders in chronic fatigue and chronic fatigue syndrome. J Psychosom Res. 1997 Jan;42(1):87-94. http://www.ncbi.nlm.nih.gov/pubmed/9055216

 

In vitro effects of echinacea and ginseng on natural killer and antibody-dependent cell cytotoxicity in healthy subjects and chronic fatigue syndrome or acquired immunodeficiency syndrome patients

Abstract:

Extracts of Echinacea purpurea and Panax ginseng were evaluated for their capacity to stimulate cellular immune function by peripheral blood mononuclear cells (PBMC) from normal individuals and patients with either the chronic fatigue syndrome or the acquired immunodeficiency syndrome.

PBMC isolated on a Ficoll-hypaque density gradient were tested in the presence or absence of varying concentrations of each extract for natural killer (NK) cell activity versus K562 cells and antibody-dependent cellular cytotoxicity (ADCC) against human herpesvirus 6 infected H9 cells. Both echinacea and ginseng, at concentrations > or = 0.1 or 10 micrograms/kg, respectively, significantly enhanced NK-function of all groups. Similarly, the addition of either herb significantly increased ADCC of PBMC from all subject groups.

Thus, extracts of Echinacea purpurea and Panax ginseng enhance cellular immune function of PBMC both from normal individuals and patients with depressed cellular immunity.

 

Source: See DM, Broumand N, Sahl L, Tilles JG. In vitro effects of echinacea and ginseng on natural killer and antibody-dependent cell cytotoxicity in healthy subjects and chronic fatigue syndrome or acquired immunodeficiency syndrome patients. Immunopharmacology. 1997 Jan;35(3):229-35. http://www.ncbi.nlm.nih.gov/pubmed/9043936

 

Chronic fatigue syndrome

Abstract:

Chronic fatigue syndrome (CFS) has emerged as a public health concern over the past decade. A working case definition was created in 1988 and revised in 1994, and this has been used to establish prevalence estimates using physician-based surveillance and an a random digit dial telephone survey. Although CFS has some characteristics of an infectious disease, so far no infectious agent has been associated with the illness. Studies of immune function in CFS patients failed to detect differences between cases and healthy controls. However, when cases were subgrouped according to whether they had a sudden or gradual onset, differences in immunologic markers were detected between cases and their matched controls.

 

Source: Mawle AC. Chronic fatigue syndrome. Immunol Invest. 1997 Jan-Feb;26(1-2):269-73. http://www.ncbi.nlm.nih.gov/pubmed/9037629

 

Cognitive slowing and working memory difficulties in chronic fatigue syndrome

Abstract:

OBJECTIVE: Patients with chronic fatigue syndrome (CFS) commonly report problems with attention, memory, learning, and speed of cognitive processing. This study attempted to evaluate these complaints using objective test criteria.

METHOD: A test battery composed of six tests assessing these cognitive functions was given on two consecutive days. Twenty CFS patients were compared with 20 healthy control subjects and 14 patients with a history of major depression or dysthymia matched by age, intelligence, education level, and sex.

RESULTS: Compared with control subjects, CFS patients consistently scored lower on tests in which motor and cognitive processing speeds were a critical factor, eg, reaction-time tasks. They also had more difficulty on working-memory tests in which rapid cognitive processing speed is also an important factor. The effort made on the first day of testing did not result in a decline in cognitive function on the following day. CFS patients did not qualify as having affective disorder by several different diagnostic criteria. Nonetheless, CFS patients’ test performances did not differ from patients with a history of major depression or dysthymia.

CONCLUSIONS: It is concluded that, although CFS and major depression and dysthymia have distinct clinical features, these disorders have slowed motor and cognitive processing speed in common.

Comment in: Cognitive slowing in chronic fatigue syndrome (CFS) [Psychosom Med. 1997]

 

Source: Marshall PS, Forstot M, Callies A, Peterson PK, Schenck CH. Cognitive slowing and working memory difficulties in chronic fatigue syndrome. Psychosom Med. 1997 Jan-Feb;59(1):58-66. http://www.ncbi.nlm.nih.gov/pubmed/9021867