Impaired oxygen delivery to muscle in chronic fatigue syndrome

The purpose of this study was to determine if chronic fatigue syndrome (CFS) is associated with reduced oxygen delivery to muscles. Patients with CFS according to CDC (Center for Disease Control) criteria (n=20) were compared with normal sedentary subjects (n=12). Muscle oxygen delivery was measured as the rate of post-exercise and post-ischaemia oxygen-haem resaturation. Oxygen-haem resaturation was measured in the medial gastrocnemius muscle using continuous-wavelength near-IR spectroscopy. Phosphocreatine resynthesis was measured simultaneously using (31)P magnetic resonance spectroscopy. The time constant of oxygen delivery was significantly reduced in CFS patients after exercise (46.5+/-16 s; mean+/-S.D.) compared with that in controls (29.4+/-6.9 s). The time constant of oxygen delivery was also reduced (20.0+/-12 s) compared with controls (12.0+/-2.8 s) after cuff ischaemia. Oxidative metabolism was also reduced by 20% in CFS patients, and a significant correlation was found between oxidative metabolism and recovery of oxygen delivery. In conclusion, oxygen delivery was reduced in CFS patients compared with that in sedentary controls. This result is consistent with previous studies showing abnormal autonomic control of blood flow. Reduced oxidative delivery in CFS patients could be specifically related to CFS, or could be a non-specific effect of reduced activity levels in these patients. While these results suggest that reduced oxygen delivery could result in reduced oxidative metabolism and muscle fatigue, further studies will be needed to address this issue.

Absence of Borrelia burgdorferi-specific immune complexes in chronic fatigue syndrome

Chronic fatigue syndrome (CFS) and Lyme disease often share clinical features, especially fatigue, contributing to concern that Borrelia burgdorferi (Bb), the cause of Lyme disease, may underlie CFS symptoms. We examined 39 CFS patients and 40 healthy controls with a Bb immune complex test. Patients and controls were nonreactive. Centers for Disease Control and Prevention-defined CFS patients lacking antecedent signs of Lyme disease--erythema migrans, Bell's palsy, or large joint arthritis--are not likely to have laboratory evidence of Bb infection.

TNF-alpha and chronic fatigue syndrome

Based upon the clinical presentation of chronic fatigue syndrome (CFS), we hypothesized that proinflammatory cytokines may play a role in the pathogenesis of the disease. We therefore undertook a retrospective cross-sectional study to examine the role of TNF-alpha in patients with CFS. Our results suggest a significant increase serum TNF-alpha in patients with CFS (P<0.0001) compared to non-CFS controls. This study supports the further examination of the role of proinflammatory mediators in CFS. Furthermore, the clinical testing of TNF-alpha blockers and other antiinflammatory agents for the treatment of this disease is warranted.

Differences in adrenal steroid profile in chronic fatigue syndrome, in depression and in health

BACKGROUND

Hyperactivity and hypoactivity of the HPA have been forwarded as of pathophysiological relevance in major depressive disorder and chronic fatigue syndrome (CFS), respectively.

METHODS

This study examines cortisol levels in the two disorders, and also assesses levels of the adrenal androgens, dehydroepiandrosterone (DHEA) and its sulphate derivative (DHEA-S), and 17-alpha-hydroxyprogesterone; 15 subjects with CFS diagnosed according to CDC criteria, 15 subjects with DSM III-R major depression and 11 healthy subjects were compared.

RESULTS

DHEA and DHEA-S levels were significantly lower in the CFS compared to the healthy group; DHEA-S levels, but not DHEA, were lower in the depressives; cortisol and 17-alpha-hydroxyprogesterone did not differ between the three groups.

CONCLUSIONS

A potential role for DHEA, both therapeutically and as a diagnostic tool, in CFS, is suggested.

Downregulation of RNase L inhibitor correlates with upregulation of interferon-induced proteins (2-5A synthetase and RNase L) in patients with chronic fatigue immune dysfunction syndrome

Chronic Fatigue Immune Dysfunction Syndrome (CFIDS) is a disorder characterized by debilitating fatigue associated with immunological abnormalities and cognitive impairments. The recently cloned RNase L Inhibitor (RLI) gene encodes a specific protein which is believed to regulate 2-5A synthetase and RNase L activity via the formation of a latent heterodimeric protein complex. In the present study, we investigated the levels of 2-5A synthetase, RNase L and RLI in patients with CFIDS as compared to healthy controls. Quantitative Competitive PCR (Q/C PCR) analysis showed a statistically significant decrease in RLI mRNA present in the peripheral blood lymphocytes (PBL) of patients with CFIDS (n = 25, mean = 569, S.E = 154) as compared to RLI mRNA level present in peripheral blood lymphocytes (PBL) of healthy controls (n = 15, mean = 2296, S.E = 506; p < 0.0001). The decrease in RLI mRNA in CFIDS individuals correlated directly with RLI and RLI: RNase L protein ratio while showing an inverse relationship to the 2-5A synthetase and RNase L activity. This RLI mRNA and protein deficiency in CFIDS patients may explain the increase in activity of RNase L found in CFIDS patients. The unidirectional decrease in RLI message and protein levels in CFIDS individuals may contribute to the destabilization of the latent RLI:RNase L heterodimeric protein complex, resulting in the excessive activation of RNase L shown in this study. The increased activation of RNase L may result in an increased cellular RNA turnover and subsequent inhibition of protein synthesis; thus resulting in general fatigue, myalgia muscle weakness and other symptomatologies shown in CFIDS patients. Furthermore, this data supports the hypothesis that the antiviral 2-5 oligoadenylate synthetase (2-5OAS) overexpression in individuals with CFIDS correlates with an increase in RNase L activity and with a decrease in RNase L inhibitor.

Vitamin B status in patients with chronic fatigue syndrome

Some patients with chronic fatigue syndrome say they benefit from taking vitamin supplements. We assessed functional status for the B vitamins pyridoxine, riboflavin and thiamine in 12 vitamin-untreated CFS patients and in 18 healthy controls matched for age and sex. Vitamin-dependent activities--aspartate aminotransferase (AST) for pyridoxine, glutathione reductase (GTR) for riboflavin, transketolase (TK) for thiamine--were measured in erythrocyte haemolysates before and after in-vitro addition of the relevant vitamin. For all three enzymes basal activity (U/g Hb) was lower in CFS patients than in controls: AST 2.84 (SD 0.62) vs 4.61 (1.43), P < 0.001; GTR 6.13 (1.89) vs 7.42 (1.25), P < 0.04; TK 0.50 (0.13) vs 0.60 (0.07), P < 0.04. This was also true of activated values: AST 4.91 (0.54) vs 7.89 (2.11), P < 0.001; GTR 8.29 (1.60) vs 10.0 (1.80), P < 0.001; TK 0.56 (0.19) vs 0.66 (0.08), P < 0.07. The activation ratios, however, did not differ between the groups. These data provide preliminary evidence of reduced functional B vitamin status, particularly of pyridoxine, in CFS patients.

The role of essential fatty acids in chronic fatigue syndrome. A case-controlled study of red-cell membrane essential fatty acids (EFA) and a placebo-controlled treatment study with high dose of EFA

OBJECTIVE

To replicate the treatment study by Behan et al. (1990) using current research criteria for Chronic Fatigue Syndrome (CFS).

METHOD

Fifty patients who fulfilled the Oxford Criteria for CFS were randomly allocated to treatment with either Efamol Marine or placebo for 3 months. They were seen monthly and completed a physical symptoms checklist and the Beck Inventory for Depression and reported if they were the same, better or worse at the end of the study.

RESULTS

Symptoms generally improved with time but not significantly and there were no significant differences between the treatment and placebo groups. Pretreatment red-cell membrane (RBC) lipids of patients compared with age-and sex-matched normal controls showed no significant differences.

DISCUSSION

The results of this study contrast sharply with the previous study where 85% of patients had a clinically significant improvement of symptoms with Efamol Marine over a 3-month treatment period.

Multiplex PCR for the detection of Mycoplasma fermentans, M. hominis and M. penetrans in cell cultures and blood samples of patients with chronic fatigue syndrome

A multiplex polymerase chain reaction (PCR) was initially developed to detect the presence of mycoplasma genus DNA sequences in cell cultures and to differentiate between three human pathogenic mycoplasma species simultaneously. The assay in turn, proved to be a useful tool for the detection of mycoplasma infection in human DNA samples. One set of oligonucleotide primers which are specific for a highly conserved region among all members of the genus mycoplasma along with three other primer sets which are specific for Mycoplasma fermentans, Mycoplasma hominis andMycoplasma penetrans species were used in this assay. The sensitivity of detection was determined by infecting peripheral blood mononuclear cells (PBMC) of healthy individuals with known bacterial copy numbers from each species, extracting the DNA, and subjecting 1 microgram of DNA from each sample to 40 cycles of amplification. By using agarose gel electrophoresis the detection level was determined to be 7, 7, 9 and 15 mycoplasma cells per microgram of human genomic DNA for M. genus,M. fermentans, M. hominis and M. penetrans, respectively. The assay was applied to DNA extracted from the PBMCs of individuals suffering from chronic fatigue syndrome (CFS) (n=100) as determined by the Center for Disease Control (CDC) criteria, and compared to healthy individuals (n=100). The percentage of M. genus infection was found to be 52% in CFS patients and only 15% in healthy individuals. Mycoplasma fermentans, M. hominis andM. penetrans were detected in 32, 9 and 6% of the CFS patients while they were detected in 8, 3 and 2% of the healthy control subjects, respectively. This assay provides a rapid and cost efficient procedure to screen either cell cultures or clinical samples for the presence of three potentially pathogenic species of mycoplasma with a high level of sensitivity and specificity.

[Risk factors for ischemic heart disease in patients with chronic fatigue syndrome]

Risk factors of coronary artery disease (CAD) between a group of patients suffering of chronic fatigue syndrome (CFS) and a control group of healthy persons (whose exercise activity was not health-limited) were compared. Thirty three patients (27 women, 6 men, average age 39.9 +/- 11.7 years) and the same number of controls matched in age (39.8 +/- 10.3 years), gender and body weight. The Minnesota Questionnaire (by Taylor) and the Compendium of Physical Activities (by Ainsworth) were used to estimate total energetic expenditure in exercise activity as well as in job. The risk factors of CAD in the patients with CFS were not higher than in the control group. Aerobic physical fitness, basic anthropometric data, blood pressure, spectrum of blood lipoproteins, blood uric acid and smoking habits were not different between the compared groups. Patients suffering from CFS had lower total energetic expenditure in exercise activity. Nevertheless, this significant difference in sports activity was not large enough to cause any difference in risk factors of CAD between the CFS patients and the control group.

Low-dose hydrocortisone for treatment of chronic fatigue syndrome: a randomized controlled trial

CONTEXT

Chronic fatigue syndrome (CFS) is associated with a dysregulated hypothalamic-pituitary adrenal axis and hypocortisolemia.

OBJECTIVE

To evaluate the efficacy and safety of low-dose oral hydrocortisone as a treatment for CFS.

DESIGN

A randomized, placebo-controlled, double-blind therapeutic trial, conducted between 1992 and 1996.

SETTING

A single-center study in a tertiary care research institution.

PATIENTS

A total of 56 women and 14 men aged 18 to 55 years who met the 1988 Centers for Disease Control and Prevention case criteria for CFS and who withheld concomitant treatment with other medications.

INTERVENTION

Oral hydrocortisone, 13 mg/m2 of body surface area every morning and 3 mg/m2 every afternoon, or placebo, for approximately 12 weeks.

MAIN OUTCOME MEASURES

A global Wellness scale and other self-rating instruments were completed repeatedly before and during treatment. Resting and cosyntropin-stimulated cortisol levels were obtained before and at the end of treatment. Patients recorded adverse effects on a checklist.

RESULTS

The number of patients showing improvement on the Wellness scale was 19 (54.3%) of 35 placebo recipients vs 20 (66.7%) of 30 hydrocortisone recipients (P =.31). Hydrocortisone recipients had a greater improvement in mean Wellness score (6.3 vs 1.7 points; P=.06), a greater percentage (53% vs 29%; P=.04) recording an improvement of 5 or more points in Wellness score, and a higher average improvement in Wellness score on more days than did placebo recipients (P<.001). Statistical evidence of improvement was not seen with other self-rating scales. Although adverse symptoms reported by patients taking hydrocortisone were mild, suppression of adrenal glucocorticoid responsiveness was documented in 12 patients who received it vs none in the placebo group (P<.001).

CONCLUSIONS

Although hydrocortisone treatment was associated with some improvement in symptoms of CFS, the degree of adrenal suppression precludes its practical use for CFS.

Low levels of serum acylcarnitine in chronic fatigue syndrome and chronic hepatitis type C, but not seen in other diseases

Recently, we found a serum acylcarnitine (ACR) deficiency in Japanese patients with chronic fatigue syndrome (CFS). To clarify whether this ACR abnormality is a characteristic of CFS or not, we also studied the levels of serum carnitine in Swedish subjects. Both serum ACR and free carnitine (FCR) levels in normal healthy subjects were quite different between Japanese (n=131) and Swedish people (n=46) (p<0.001). However, it is confirmed that Swedish patients with CFS (n=57) also had serum ACR deficiency (p<0.001). When we studied the levels of serum ACR and FCR in Japanese patients with various kinds of diseases (CFS, hematological malignancies, chronic pancreatitis, hypertension, diabetes mellitus, chronic hepatitis type C, psychiatric diseases), a significant decrease in the levels of serum ACR was only found in patients with CFS and chronic hepatitis type C (p<0.001). Therefore, we concluded that ACR deficiency in serum might be a characteristic abnormality in only certain types of diseases.

The low dose ACTH test in chronic fatigue syndrome and in health

OBJECTIVE

A number of dynamic tests of the hypothalamic-pituitary-adrenal axis provide evidence for a mild central adrenal insufficiency in chronic fatigue syndrome (CFS). The 1 microgram adrenocorticotropin (ACTH) test has been proposed to be more sensitive than the standard 250 micrograms ACTH test in the detection of subtle pituitary-adrenal hypofunctioning. We aimed to establish whether the 1 microgram ACTH test would support such a dysregulation in CFS, and also, given the relative novelty of this test in clinical practice and the uncertainty with regard to appropriate cut-off values for normality, to compare our healthy volunteer data with those of previous studies.

PATIENTS AND DESIGN

Twenty subjects with CFS, diagnosed according to Centres for Disease Control and Prevention criteria, were compared with 20 healthy volunteer subjects. All participants underwent a 1 microgram ACTH test beginning at 1400 h. Plasma samples for cortisol estimation were drawn at 0, +30 and +40 min.

RESULTS

Baseline cortisol values did not differ between CFS patients and healthy subjects. The delta cortisol (maximum increment from baseline) value was significantly lower in the CFS than the volunteer group (P < 0.05). Comparison of the +30 min cortisol values revealed no significant differences. Using an incremental cortisol of > 250 nmol/l as an arbitrary cutoff point, two (10%) of the healthy subjects and nine (45%) of the CFS subjects failed the test on this basis (chi 2 = 4.3, df = 38, P < 0.05).

CONCLUSIONS

This study provides further evidence for a subtle pituitary-adrenal insufficiency in subjects with chronic fatigue syndrome compared to healthy volunteers. Disparities between our healthy volunteer data and those of other groups using the 1 microgram ACTH test suggest that the test may not be as reliable as previously indicated.

Effect of growth hormone treatment in patients with chronic fatigue syndrome: a preliminary study

The efficacy of growth hormone (GH) therapy was evaluated in patients with chronic fatigue syndrome (CFS) who had peak serum GH levels below 10 microg/l during stage-controlled sleep. Twenty patients (7 men, 13 women; age range, 30-60 years) with CFS were randomized to receive placebo or GH therapy, 6.7 microg/kg/day (0.02 IU/kg/day), for 12 weeks. Following this double-blind treatment period, the 17 patients remaining in the study were given GH therapy at the above dose for an open period of 9 months. Mean (+/- SD) serum levels of insulin-like growth factor I (IGF-I) increased during GH treatment, from 173 +/- 46 microg/I to 296 +/- 89 microg/l (P < 0.001); IGF-I SDS values increased from -0.45 +/- 1.14 to +1.43 +/- 1.09 (P < 0.001). Fat-free mass and total body water were significantly increased after 12 months of treatment. Although quality of life, as assessed using two different questionnaires, did not improve significantly during GH treatment, four patients were able to resume work after a long period of sick leave.

Secretion of growth hormone in patients with chronic fatigue syndrome

Decreased serum levels of insulin-like growth factor I (IGF-I) are common in patients with fibromyalgia, which is frequently associated with chronic fatigue syndrome (CFS). Twenty patients with CFS (7 men, 13 women; age range, 30-60 years) and age- and sex-matched controls were tested for peak GH responses to insulin-induced hypoglycaemia and arginine administration. Nocturnal secretion of GH and serum levels of IGF-I were also measured. Serum IGF-I SDS (+/- SD) was significantly lower in patients with CFS than in controls (SDS, -0.39 +/- 1.07 vs 0.33 +/- 0.84; P = 0.02). Patients with CFS also tended to have reduced nocturnal secretion of GH (area under the curve, 32.4 +/- 18.3 vs 62.7 +/- 43.7 microg/l/15 minutes; P= 0.06), but peak GH responses to insulin-induced hypoglycaemia and arginine administration did not differ significantly between the two groups. It is not clear whether the tendency for impaired spontaneous nocturnal GH secretion in patients with CFS is a cause or an effect of the condition.

A comparison of salivary cortisol in chronic fatigue syndrome, community depression and healthy controls

BACKGROUND

Previous studies reporting cortisol hyposecretion in chronic fatigue syndrome may have been confounded by venepuncture, fasting and hospitalisation.

METHODS

Morning and evening salivary cortisol were obtained on consecutive days in the first 3 days of the menstrual cycle and compared in three samples of women taking no medication and matched for age: 14 patients with chronic fatigue syndrome, 26 community cases of ICD-10 current depressive episodes and 131 healthy community controls.

RESULTS

The mean evening cortisol was significantly lower in the chronic fatigue syndrome patients compared to controls with depression (P = 0.02) and healthy controls (P = 0.005). Chronic fatigue syndrome patients without psychiatric disorder had significantly lower morning salivary cortisols compared to controls (P = 0.009).

CONCLUSION

Chronic fatigue syndrome patients display cortisol hyposecretion in saliva as well as plasma compared to patients with depression and healthy controls.

LIMITATIONS

Small samples of female patients with cortisol estimated at only two time points in the day. Cortisol secretion may be secondary to other neurotransmitter abnormalities or other physiological or lifestyle factors in chronic fatigue syndrome patients.

CLINICAL RELEVANCE

Chronic fatigue syndrome is biochemically distinct from community depression.

Dehydroepiandrosterone sulfate deficiency in chronic fatigue syndrome

The chronic fatigue syndrome (CFS) is a condition of unknown etiology, characterized by a persistent debilitating fatigue, the muscle-related symptoms and the neuropsychiatric symptoms. Recently, it has been reported that the patients with CFS might have impaired activation of the hypothalamic-pituitary-adrenal axis, and suggested that a part of the patho-genesis of CFS might be associated with abnormalities of the endocrine system. Herein, we show that the majority of Japanese patients with CFS had a serum dehydroepiandrosterone sulfate (DHEA-S) deficiency. Serum DHEA-S is one of the most abundantly produced hormones which is secreted from the adrenal glands, and its physiological function is thought to be a precursor of sex steroids. DHEA-S has recently been shown to have physiological properties, such as neurosteroids, which are associated with such psychophysiological phenomena as memory, stress, anxiety, sleep and depression. Therefore, the deficiency of DHEA-S might be related to the neuropsychiatric symptoms in patients with CFS.

Elevated apoptotic cell population in patients with chronic fatigue syndrome: the pivotal role of protein kinase RNA

OBJECTIVES

A prominent feature of chronic fatigue syndrome (CFS) is a disordered immune system. Recent evidence indicates that induction of apoptosis might be mediated in a dysregulated immune system by the upregulation of growth inhibitory cytokines. Therefore, the purpose of this study was to evaluate the apoptotic cell population, interferon-alpha (IFN-alpha) and the IFN-induced protein kinase RNA (PKR) gene transcripts in peripheral blood lymphocytes (PBL) of CFS individuals, as compared to healthy controls.

SUBJECTS AND METHODS

PBL were isolated from CFS (n = 29) and healthy control individuals (n = 15) and subjected to quantitative analysis of apoptotic cell population and cell cycle progression by flow cytometry. Quantitative competitive polymerase chain reaction (Q/C PCR) and Western blot analysis were used to assess the levels of PKR mRNA and protein in control and CFS individuals. In addition, circulating IFN-alpha was measured by ELISA assay.

RESULTS

Increased apoptotic cell population was observed in CFS individuals, as compared to healthy controls (26.6 +/- 12.9% and 9.9 +/- 4.2%, respectively). The increased apoptotic subpopulation in CFS individuals was accompanied by an abnormal cell arrest in the S phase and the G2/M boundary of the cell cycle as compared to the control group (8.6 +/- 1.2 to 22.8 +/- 2.4 and 3.6 +/- 0.82 to 24.3 +/- 3.4, respectively). In addition, CFS individuals exhibited enhanced PKR mRNA and protein levels (mean basal level 3538 +/- 1050 and 2.7 +/- 0.26, respectively) as compared to healthy controls (mean basal level 562 +/- 162 and 0.89 +/- 0.18, respectively). In 50% of the CFS samples (n = 29) treated with 2-aminopurine (2-AP) (a potent inhibitor of PKR) the apoptotic population was reduced by more then 50%.

CONCLUSIONS

PKR-mediated apoptosis in CFS individuals may contribute to the pathogenesis and the fatigue symptomatology associated with CFS.

[High prevalence without reactivation of herpes virus 6 in subjects with chronic fatigue syndrome]

INTRODUCTION

Chronic fatigue syndrome (CFS) is a disorder of unknown etiology. Some viruses have been associated with CFS etiology, specially herpesviruses, enteroviruses and retroviruses. Some studies suggest an association between human herpesvirus-6 (HHV-6) and CFS. In order to know if there is an active HHV-6 infection in CFS patients we studied the immunologic and virologic status of HHV-6.

MATERIALS AND METHODS

Twenty patients with CFS were studied. IgG and IgM anti HHV-6 were determined by indirect immunofluorescence assay. DNA from serum and peripheral blood mononuclear cells (PBMC) were studied by dot- and Southern-blotting and nested-PCR to detect HHV-6 DNA. HHV-6 RNA from PBMC were amplified by RT(retrotranscription)-PCR.

RESULTS

Ten patients (50%) had IgG anti-HHV-6 in serum but none had IgM anti-HHV-6. Dot-blotting of DNA from 200 microliters of serum and Southern-blotting of 10 micrograms of PBMC DNA were negative. Nested-PCR from sera were negative. Nested-PCR with 1 microgram PBMC DNA were positive in 8 out 20 (40%) and with 5 micrograms PBMC DNA were positive in 16 out of 20 (80%). No viral RNA were detected in PBMC.

CONCLUSIONS

There is a high proportion of CFS patients infected with HHV-6 but with low viral load. Results do not support HHV-6 reactivation in CFS patients.

Changes in growth hormone, insulin, insulinlike growth factors (IGFs), and IGF-binding protein-1 in chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is characterized by severe physical and mental fatigue of central origin. Similar clinical features may occur in disorders of the hypothalamopituitary axis. The aim of the study was to determine whether patients with CFS have abnormalities of the growth hormone/insulinlike growth factor (GH-IGF) axis basally or following hypothalamic stimulation with insulin-induced hypoglycemia. We compared levels of GH, IGF-I, IGF-II, IGF-binding protein-1 (IGFBP-1), insulin, and C-peptide in nondepressed CFS patients and normal controls. We found attenuated basal levels of IGF-I (214 +/- 17 vs. 263.4 +/- 13.4 micrograms/L, p = .036) and IGF-II (420 +/- 19.8 vs. 536 +/- 24.3 micrograms/L, p = .02) in CFS patients and a reduced GH response to hypoglycemia (peak GH; 41.9 +/- 11.5 vs. 106.0 +/- 25.6 mU/L, p = .017). Insulin levels were higher (7.6 +/- 1.0 vs. 4.3 +/- 0.8 mU/L, p = .02) and IGFBP-1 levels were lower (19.7 +/- 4.6 vs. 43.2 +/- 2.7 mg/L, p = .004) in CFS patients compared with controls. This study provides preliminary data abnormalities of the GH-IGF axis in CFS. It is not apparent whether these changes are components of a primary pathological process or are acquired secondary to behavioral aspects of CFS such as reduced physical activity.

Elevation of bioactive transforming growth factor-beta in serum from patients with chronic fatigue syndrome

The level of bioactive transforming growth factor-beta (TGF-beta) was measured in serum from patients with chronic fatigue syndrome (CFS), healthy control subjects, and patients with major depression, systemic lupus erythematosis (SLE), and multiple sclerosis (MS) of both the relapsing/remitting (R/R) and the chronic progressive (CP) types. Patients with CFS had significantly higher levels of bioactive TGF-beta levels compared to the healthy control major depression, SLE, R/R MS, and CP MS groups (P < 0.01). Additionally, no significant differences were found between the healthy control subjects and any of the disease comparison groups. The current finding that TGF-beta is significantly elevated among patients with CFS supports the findings of two previous studies examining smaller numbers of CFS patients. In conclusion, TGF-beta levels were significantly higher in CFS patients compared to patients with various diseases known to be associated with immunologic abnormalities and/or pathologic fatigue. These findings raise interesting questions about the possible role of TGF-beta in the pathogenesis of CFS.

High frequency of autoantibodies to insoluble cellular antigens in patients with chronic fatigue syndrome

OBJECTIVE

To elucidate the humoral immune response in patients with chronic fatigue syndrome (CFS), by identification and characterization of autoantibodies.

METHODS

Initial immunofluorescence histochemistry studies of sera using human HEp-2 cell substrate were followed by antibody class subtyping and colocalization studies with reference antibodies. Association of CFS autoantigens with insoluble cellular components was determined by in situ extraction of soluble components and subsequent immunofluorescence histochemistry studies on the extracted cell substrate.

RESULTS

Of 60 CFS patients, 41 (68%) were positive for antinuclear antibodies. Localization of nuclear staining was found at the nuclear envelope (52%), in reticulated speckles (25%), in nucleoli (13%), and in dense fine speckles (5%). Twenty-eight CFS sera (47%) also had antibodies to cytoplasmic antigens. The major cytoplasmic staining pattern was of the intermediate filament type (35%). The observed nuclear envelope pattern of staining co-localized with lamina-associated polypeptide 2 (an integral nuclear membrane protein), the reticulated speckle pattern co-localized with non-small nuclear RNP splicing factor SC-35, and the intermediate filament pattern co-localized with vimentin. The intermediate filament antigen was shown to be vimentin in immunoblotting experiments using recombinant human vimentin, and one of the nuclear envelope antigens was shown previously to be lamin B1. Fifty of the 60 CFS patients (83%) had antibodies to one or another of these antigens, all of which are relatively insoluble cellular antigens, whereas a control group of patients without chronic fatigue had a significantly lower frequency of such antibodies (17%).

CONCLUSION

The high frequency of autoantibodies to insoluble cellular antigens in CFS represents a unique feature which might help to distinguish CFS from other rheumatic autoimmune diseases.

Gender differences in host defense mechanisms

Extensive studies in both humans and animals have shown that females express enhanced levels of immunoreactivity compared to males. Whereas this provides females with increased resistance to many types of infection, it also makes them more susceptible to autoimmune diseases. This review will focus on gender-related differences in non-specific host defense mechanisms with a particular emphasis on monocyte/macrophage function and a primary product of monocytes: interleukin-1 (IL-1). Immunomodulatory cytokines such as IL-1 are influenced by gender-sensitive hormones, and reciprocally, these cytokines influence gender-specific hormones and tissues. Patients with chronic fatigue syndrome (CFS) are predominantly women, therefore it may be useful to look toward gender-specific differences in immune function to find a key for this poorly understood syndrome.

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

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.

Somatomedin C (insulin-like growth factor I) levels in patients with chronic fatigue syndrome

Chronic fatigue syndrome is a disorder clinically quite similar to fibromyalgia syndrome, and it is of interest to examine if these two syndromes have pathogenetic as well as clinical features in common. Somatomedin C levels have been found to be lower in patients with fibromyalgia syndrome than in healthy controls. An attractive hypothesis relating sleep disturbance, altered somatotropic neuroendocrine function and fibromyalgia symptoms has been put forward as a plausible pathogenic mechanism for fibromyalgia syndrome. We therefore sought to investigate the level of somatomedin C in patients with chronic fatigue syndrome. Somatomedin C levels were determined by radioimmunoassay in frozen serum specimens from 49 patients with CFS and 30 healthy blood donor control subjects of similar age and gender. Somatomedin C levels were higher in patients with CFS than in healthy control subjects (255.3 +/- 68.5 vs 211.9 +/- 76.2, P = 0.01). There was no effect of gender, use of nonsteroidal anti-inflammatory drugs or tricyclic drugs on levels of somatomedin C. There was a tendency for somatomedin C levels to fall with age. In contrast to patients with fibromyalgia, in whom levels of somatomedin C have been found to be reduced, levels in patients with CFS were found to be elevated. Thus, despite the clinical similarities between these two conditions, they may be associated with different abnormalities of sleep and/or of the somatotropic neuroendocrine axis.

Serum carnitine and disabling fatigue in multiple sclerosis

The serum concentrations of total, free and acylcarnitine were compared in 25 patients with multiple sclerosis (MS) and among age- and sex-matched normal controls by the new enzymatic cycling method in order to clarify whether the fatigue in MS might be due to possible carnitine-related fatty acid metabolic abnormalities in the mitochondria of skeletal muscles. Patients with MS were divided into those with and those without excessive fatigue. Levels of total and free carnitine were not significantly different between MS patients and normal controls. Levels of acylcarnitine, whose decrease in chronic fatigue syndrome has been reported, were also similar between MS patients and normal controls. There was no difference in these carnitine levels between MS patients with and without excessive fatigue. We argue that acylcarnitine deficiency and fatty acid metabolic dysfunction in mitochondria are not relevant to the excessive fatigue in patients with MS, and further explanatory investigations are to be sought.

Increased prolactin response to buspirone in chronic fatigue syndrome

We studied the endocrine and subjective responses that followed acute administration of the 5-HT1A receptor agonist buspirone (0.5 mg/kg orally) in 11 male patients with chronic fatigue syndrome (CFS) and a group of matched healthy controls. Patients with CFS had significantly higher plasma prolactin concentrations and experienced more nausea in response to buspirone than did controls. However, the growth hormone response to buspirone did not distinguish CFS patients from controls. Our data question whether the enhancement of buspirone-induced prolactin release in CFS is a consequence of increased sensitivity of post-synaptic 5-HT1A receptors. It is possible that the increased prolactin response to buspirone in CFS could reflect changes in dopamine function.

Psychosocial risk factors for chronic fatigue and chronic fatigue syndrome following presumed viral illness: a case-control study

This study investigated psychosocial morbidity, coping styles and health locus of control in 64 cases with and without chronic fatigue identified from a cohort of primary care patients recruited 6 months previously with a presumed, clinically diagnosed viral illness. A significant association between chronic fatigue and psychosocial morbidity, somatic symptoms and escape-avoidance coping styles was shown. Chronic fatigue cases were significantly more likely to have a past psychiatric history and a current psychiatric diagnosis based on a standardized clinical interview. Twenty-three of the cases fulfilled criteria for chronic fatigue syndrome (CFS). Such cases were significantly more fatigued than those not fulfilling criteria, but had little excess psychiatric disorder. A principal components analysis provided some evidence for chronic fatigue being separable from general psychosocial morbidity but not from the tendency to have other somatic complaints. Past psychiatric history and psychological distress at the time of the viral illness were risk factors for psychiatric 'caseness' 6 months later, while presence of fatigue, psychologising attributional style and sick certification were significant risk factors for CFS. These findings extend a previous questionnaire study of predictors of chronic 'post-viral' fatigue.

Dissociation of body-temperature and melatonin secretion circadian rhythms in patients with chronic fatigue syndrome

Many patients with chronic fatigue syndrome (CFS) display features of hypothalamic dysfunction. We have investigated aspects of circadian rhythmicity, an important hypothalamic function, in 20 CFS patients and in 17 age- and sex-matched healthy control subjects. There were no differences between the two groups in the amplitude, mesor (mean value) or timing of the peak (acrophase) of the circadian rhythm of core temperature, or in the timing of the onset of melatonin secretion. However, the CFS patients showed no significant correlation between the timing of the temperature acrophase and the melatonin onset (P < 0.5), whereas the normal significant correlation was observed in the controls (P < 0.05). Dissociation of circadian rhythms could be due to the sleep deprivation and social disruption, and/or the reduction in physical activity which typically accompany CFS. By analogy with jet-lag and shift-working, circadian dysrhythmia could be an important factor in initiating and perpetuating the cardinal symptoms of CFS, notably tiredness, impaired concentration and intellectual impairment.

Bioaccumulated chlorinated hydrocarbons and red/white blood cell parameters

The potential relationships between chlorinated hydrocarbon contamination in human serum and red/white blood cell profiles were investigated by multivariate techniques to assess the cellular response patterns to high and low organochlorine levels in the serum. Twenty-three healthy control subjects and fourteen patients with unexplained and persistent fatigue were divided on the basis of (a) high or low total organochlorine content, (b) high or low DDE (1,1-dichloro-2,2-bis(p-chlorophenyl) ethene) content, and (c) high or low HCB (hexachlorobenzene) content. Discriminant function analysis revealed that the groups with high organochlorine content had significantly different red/white blood cell profiles compared with the low organochlorine groups ((a) P < 0.017, (b) P < 0.015, and (c) P < 0.0002). As a variable, the percentage of neutrophils was the most important discriminant parameter for differentiating between the high and low total organochlorine groups. Thirteen of the fourteen fatigued patients were characterized as "high total organocholorine content" (P < 0.04). The red cell distribution width was elevated in the high DDE group (P < 0.04) and was the most important discriminant parameter for differentiating between the high and low DDE groups. The percentage of eosinophils and the hemoglobin content were both reduced in the high HCB group (P < 0.009,P < 0.003, respectively) and the percentage of eosinophils was the most important discriminant parameter for differentiating between the high and low HCB groups. Those patients with unexplained and persistent fatigue had significantly higher levels of DDE compared with the controls and had different specific blood cell responses to organochlorines compared with control subjects.

A case-control study to assess possible triggers and cofactors in chronic fatigue syndrome

PURPOSE

To assess possible triggers and cofactors for chronic fatigue syndrome (CFS) and to compare levels of selected cytokines between cases and an appropriately matched control group.

PATIENTS AND METHODS

We conducted a case-control study of 47 cases of CFS obtained through a regional CFS research program maintained at a tertiary care medical center. One age-, gender-, and neighborhood-matched control was identified for each case through systematic community telephone sampling. Standardized questionnaires were administered to cases and controls. Sera were assayed for transforming growth factor-beta (TGF-beta), interleukin-1 beta, interleukin-6, tumor necrosis factor-alpha, and antibody to Borrelia burgdorferi and Babesia microti.

RESULTS

Cases were more likely to have exercised regularly before illness onset than controls (67% versus 40%; matched odds ratio (MOR) = 3.4; 95% CI = 1.2 to 11.8; P = 0.02). Female cases were more likely to be nulliparous prior to onset of CFS than controls (51% versus 31%; MOR = 8.0; 95% CI = 1.03 to 170; P = 0.05). History of other major factors, including silicone-gel breast implants (one female case and one female control), pre-morbid history of depression (15% of cases, 11% of controls) and history of allergies (66% of cases, 51% of controls) were similar for cases and controls. However, cases were more likely to have a diagnosis of depression subsequent to their diagnosis of CFS compared to a similar time frame for controls (MOR = undefined; 95% CI lower bound = 2.5; P < 0.001). Positive antibody titers to B burgdorferi (one case and one control) and B microti (zero cases and two controls) were also similar.

CONCLUSIONS

Further investigation into the role of prior routine exercise as a cofactor for CFS is warranted. This study supports the concurrence of CFS and depression, although pre-morbid history of depression was similar for both groups.

Insulin-like growth factor-I (somatomedin C) levels in chronic fatigue syndrome and fibromyalgia

OBJECTIVE

Fibromyalgia (FM) and chronic fatigue syndrome (CFS) are similar conditions characterized by substantial fatigue, diffuse myalgias, sleep disturbances and a variety of other symptoms. Many patients with CFS meet strict criteria for FM. Recently, low insulin-like growth factor-I (IGF-I) levels have been demonstrated in patients with FM, suggesting that disruption of the growth hormone-IGF-I axis might explain the link between the muscle pain and poor sleep. Our goal was to determine whether IGF-I levels are decreased in CFS, and whether such findings are restricted to patients with concurrent FM.

METHODS

Radioimmunoassays were used to determine serum concentrations of IGF-I and its binding protein, (IGFBP-3). Subjects were 3 patients seen in a referral clinic for chronic fatigue: 15 patients with CFS, 15 who met criteria for both CFS and FM (CFS-FM), 27 with FM alone; and 15 healthy control (HC) subjects.

RESULTS

Patients and control subjects had similar demographic and clinical characteristics. No significant differences were observed among any of the 3 patient groups and control subjects in the mean concentration of either IGF-I or IGFBP-3. Likewise, the proportion of subjects with values above or below the laboratory's reference range did not differ for IGF-I or IGFBP-3.

CONCLUSIONS

These findings suggest the disruption of the growth hormone-IGF-I axis previously demonstrated in FM patients is not evident in a referral population of patients with CFS, CFS-FM, or FM.

Eosinophil cationic protein serum levels and allergy in chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is a syndrome of uncertain etiopathogenesis characterized by disabling fatigue associated with a variable number of somatic and/or neuropsychologic symptoms. In patients with CFS, several immunologic abnormalities can be detected, including a higher prevalance of allergy. The aim of this study was to determine whether CFS patients, well studied for their allergy profile, show signs of eosinophil activation, as detectable by the measurement in serum of eosinophil cationic protein (ECP) levels. In 35 consecutive CFS outpatients (diagnosis based on the Centers for Disease Control case definition), ECP was measured in serum by a competitive enzyme immunoassay (ECP-FEIA kit, Kabi Pharmacia Diagnostics, Uppsala, Sweden). Fourteen disease-free subjects with no history of CFS or allergy were selected as controls. ECP serum levels were significantly higher in CFS patients than in controls (18.0 +/- 11.3 micrograms/l vs 7.3 +/- 2.1 micrograms/l; P < 0.01). In the CFS population, the prevalence of RAST positivity to one or more allergens was 77%, while no control showed positive RAST. Twelve of the 14 CFS patients with increased ECP serum levels were RAST-positive. However, CFS RAST-positive patients had no significantly higher ECP serum levels than CFS RAST-negative patients (19.3 +/- 12.4 micrograms/l vs 13.6 +/- 3.7 micrograms/l; P = 0.4). This is the first report of increased serum levels of ECP in CFS. On the basis of the available data, it is discussed whether eosinophil activation has a pathogenetic role in CFS or is linked to the frequently associated allergic condition, or, finally, whether a common immunologic background may exist for both atopy and CFS.

Seroepidemiology of chronic fatigue syndrome: a case-control study

We performed serological testing for a large number of infectious agents in 26 patients from Atlanta who had chronic fatigue syndrome (CFS) and in 50 controls matched by age, race, and sex. We did not find any agent associated with CFS. In addition, we did not find elevated levels of antibody to any of a wide range of agents examined. In particular, we did not find elevated titers of antibody to any herpesvirus, nor did we find evidence of enteroviral exposure in this group of patients.

High incidence of antibodies to 5-hydroxytryptamine, gangliosides and phospholipids in patients with chronic fatigue and fibromyalgia syndrome and their relatives: evidence for a clinical entity of both disorders

The fibromyalgia syndrome (FMS) is one of the most frequent rheumatic disorders showing a wide spectrum of different symptoms. An association with the chronic fatigue syndrome (CFS) has been discussed. Recently, a defined autoantibody pattern consisting of antibodies to serotonin (5-hydroxytryptamine, 5-HT), gangliosides and phospholipids was found in about 70% of the patients with FMS. We were therefore interested in seeing whether patients with CFS express similar humoral immunoreactivity. Sera from 42 CFS patients were analysed by ELISA for these antibodies, and the results were compared with those previously observed in 100 FMS patients. 73% of the FMS and 62% of the CFS patients had antibodies to serotonin, and 71% or 43% to gangliosides, respectively. Antibodies to phospholipids could be detected in 54% of the FMS and 38% of the CFS patients. 49% of FMS and 17% of the CFS patients had all three antibodies in parallel, 70% and 55%, respectively had at least two of these antibody types. 21% of FMS and 29% of CFS patients were completely negative for these antibodies. Antibodies to 5-HT were closely related with FMS/CFS while antibodies to gangliosides and phospholipids could also be detected in other disorders. The observation that family members of CFS and FMS patients also had these antibodies represents an argument in favour of a genetic predisposition. These data support the concept that FMS and CFS may belong to the same clinical entity and may manifest themselves as 'psycho-neuro-endocrinological autoimmune diseases'.

A preliminary investigation of chlorinated hydrocarbons and chronic fatigue syndrome

OBJECTIVE

To determine whether serum levels of chlorinated hydrocarbons are elevated in patients with chronic fatigue syndrome.

METHODS

Chlorinated hydrocarbon levels were measured in 22 patients with chronic fatigue syndrome (CFS) (as defined by the Centers for Disease Control [CDC]); in 17 patients with CFS symptoms whose history of exposure to toxic chemicals excluded them from the research definition of CFS; and in 34 non-CFS control subjects matched for age and sex.

RESULTS

DDE (1,1-dichloro-2,2-bis (p-chlorophenyl) ethene) was detected in all serum samples at levels over 0.4 ppb. The incidence of hexachlorobenzene (HCB) contamination (> 2.0 ppb) was 45% in the CFS group, compared with 21% in the non-CFS control group (P < 0.05). The CFS group had a significantly higher total organochlorine level (15.9 ppb; SEM, 4.4) than the control group (6.3 ppb; SEM, 1.1; P < 0.05). The toxic exposure group also had a higher mean organochlorine level (13.6 ppb; SEM, 6.2) than the control group, but the difference was not statistically significant. DDE and HCB comprised more than 90% of the total organochlorines measured in each of the groups.

CONCLUSION

The results suggest that recalcitrant organochlorines may have an aetiological role in CFS. There were no significant differences in serum organochlorine concentrations between CFS patients and chronic fatigue patients with a history of toxic chemical exposure. Therefore, exclusion of patients from the CDC research definition of CFS on the basis of a reported history of known exposure to toxic chemicals is not valid. The role of low-level organochlorine bioaccumulation in the development of CFS symptoms requires further investigation.

The disease associations of the antibody response against the Epstein-Barr virus transactivator protein ZEBRA can be separated into different epitopes

The BamHI-Z-encoded Epstein-Barr virus (EBV) replication activator (ZEBRA) is a key mediator of the switch from latency to productive cycle in EBV virus. Antibodies against ZEBRA are a marker of EBV reactivation and are regularly found among patients with infectious mononucleosis (IM) or nasopharyngeal carcinoma (NPC), but are only rarely found among healthy EBV-seropositive donors. In order to define the serologically reactive epitopes in the ZEBRA protein, we synthesized a set of overlapping peptides and tested them for reactivity with serum samples from EBV-seronegative persons, patients with NPC, IM, chronic fatigue syndrome, lymphoma or from healthy donors. Three major EBV-specific epitopes were found. These epitopes were further defined and optimized using substitution or truncation analogues of the peptides. Reactivity with epitope number 22 was found in 63% of NPC patients' sera, with < 2% of healthy donors' sera being positive. Serological reactivity with epitope number 19 was associated with IM (57% positive, 5% healthy donors positive). Serum antibodies against epitope 1 were found among healthy donors, but were significantly elevated among patients with NPC, IM or lymphomas. In conclusion, different serologically reactive epitopes in the ZEBRA protein associate with different EBV-associated diseases.

Chronic fatigue syndrome: a clinical and laboratory study with a well matched control group

OBJECTIVE

To investigate the relation between severity of complaints, laboratory data and psychological parameters in patients with chronic fatigue syndrome (CFS).

SUBJECTS

Eighty-eight patients with CFS and 77 healthy controls matched for age, sex and geographical area.

METHODS

Patients and controls visited our outpatient clinic for a detailed medical history, physical examination and psychological tests: Checklist Individual Strength (CIS). Beck Depression Inventory (BDI) and Sickness Impact Profile (SIP). Venous blood was drawn for a complete blood cell count, serum chemistry panel, C-reactive protein and serological tests on a panel of infectious agents.

RESULTS

All patients fulfilled the criteria for CFS as described by Sharpe et al. (J R Soc Med 1991; 84: 118-21), only 18 patients (20.5%) fulfilled the CDC criteria. The outcome of serum chemistry tests and haematological tests were within the normal range. No significant differences were found in the outcome of serological tests. Compared to controls, significant differences were found in the results on the CIS, the BDI, and the SIP. These results varied with the number of complaints (CDC criteria). When the number of complaints was included as the covariate in the analysis, there were no significant differences on fatigue severity, depression, and functional impairment between patients who fulfilled the CDC criteria and patients who did not.

CONCLUSION

It is concluded that the psychological parameters of fatigue severity, depression and functional impairment are related to the clinical severity of the illness. Because the extensive panel of laboratory tests applied in this study did not discriminate between patients and controls, it was not possible to investigate a possible relation between the outcomes of psychological and laboratory testing.

Neuroendocrine responses to d-fenfluramine and insulin-induced hypoglycemia in chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is a disorder characterized by severe physical and mental fatigue and fatiguability of central rather than peripheral origin. We hypothesized that CFS is mediated by changes in hypothalamopituitary function and so measured the adrenocorticotrophic hormone (ACTH), cortisol, growth hormone, and prolactin responses to insulin-induced hypoglycemia, and the ACTH, cortisol, and prolactin responses to serotoninergic stimulation with dexfenfluramine in nondepressed CFS patients and normal controls. We have shown attenuated prolactin responses to hypoglycemia in CFS. There was also a greater ACTH response and higher peak ACTH concentrations (36.44 +/- 4.45 versus 25.60 +/- 2.78 pg ml), whereas cortisol responses did not differ, findings that are compatible with impaired adrenal cortical function. This study provided evidence for both pituitary and adrenal cortical impairment in CFS and further studies are merited to both confirm and determine more precisely their neurobiological basis so that rational treatments can be evolved.

Clinical laboratory test findings in patients with chronic fatigue syndrome

BACKGROUND

Results of readily available clinical laboratory tests in patients with chronic fatigue syndrome were compared with results in healthy control subjects.

METHODS

Cases consisted of all 579 patients who met either the Centers for Disease Control and Prevention, Atlanta, Ga, British, or Australian case definition for chronic fatigue syndrome. They were from chronic fatigue clinics in Boston, Mass, and Seattle, Wash. Control subjects consisted of 147 blood donors who denied chronic fatigue. Outcome measures were the results of 18 clinical laboratory tests.

RESULTS

Age- and sex-adjusted odds ratios of abnormal results, comparing cases with control subjects, were as follows: circulating immune complexes, 26.5 (95% confidence interval [CI] 3.4-206), atypical lymphocytosis, 11.4 (95% CI, 1.4-94); elevated immunoglobulin G, 8.5 (95% CI, 2.0-37); elevated alkaline phosphatase, 4.2 (95% CI, 1.6-11); elevated total cholesterol, 2.1 (95% CI, 1.2-3.4); and elevated lactic dehydrogenase, 0.30 (95% CI, 0.16-0.56). Also, antinuclear antibodies were detected in 15% of cases vs 0% in the control subjects. The results of these tests were generally comparable for the cases from Seattle and Boston. Although these tests served to discriminate the population of patients from healthy control subjects, at the individual level they were not as useful.

CONCLUSIONS

Patients with chronic fatigue syndrome who were located in two geographically distant areas had abnormalities in the results of several readily available clinical laboratory tests compared with healthy control subjects. The immunologic abnormalities are in accord with a growing body of evidence suggesting chronic, low-level activation of the immune system in chronic fatigue syndrome. While each of these laboratory findings supports the diagnosis of chronic fatigue syndrome, each lacks sufficient sensitivity to be a diagnostic test. Furthermore, the specificity of these findings relative to other organic and psychiatric conditions that can produce fatigue remains to be established.