Neurobiological aspects of the chronic fatigue syndrome

Cholestasis progression effects on long-term memory in bile duct ligation rats

BACKGROUND

There is evidence that cognitive functions are affected by some liver diseases such as cholestasis. Bile duct ligation induces cholestasis as a result of impaired liver function and cognition. This research investigates the effect of cholestasis progression on memory function in bile duct ligation rats.

MATERIALS AND METHODS

MALE WISTAR RATS WERE RANDOMLY DIVIDED INTO FIVE GROUPS, WHICH INCLUDE: control group for BDL-7, control group for BDL-21, sham group (underwent laparotomy without bile duct ligation), BDL-7 group (7 days after bile duct ligation), and BDL-21 group (21 days after bile duct ligation). Step-through passive avoidance test was employed to examine memory function. In all groups, short-term (7 days after foot shock) and long-term memories (21 days after foot shock) were assessed.

RESULTS

Our results showed that liver function significantly decreased with cholestasis progression (P < 0.01). Also our findings indicated BDL-21 significantly impaired acquisition time (P < 0.05). Memory retrieval impaired 7 (P < 0.05) and 21 days (P < 0.001) after foot shock in BDL-7 and BDL-21 groups, respectively.

CONCLUSION

Based on these findings, liver function altered in cholestasis and memory (short-term and long-term memory) impaired with cholestasis progression in bile duct ligation rats. Further studies are needed to better insight the nature of progression of brain damage in cholestatic disease.

A review of hypothalamic-pituitary-adrenal axis function in chronic fatigue syndrome

Hypothalamic-pituitary-adrenal (HPA) axis dysfunction has been found in a high proportion of chronic fatigue syndrome (CFS) patients and includes enhanced corticosteroid-induced negative feedback, basal hypocortisolism, attenuated diurnal variation, and a reduced responsivity to challenge. A putative causal role for genetic profile, childhood trauma, and oxidative stress has been considered. In addition, the impact of gender is demonstrated by the increased frequency of HPA axis dysregulation in females. Despite the temporal relationship, it is not yet established whether the endocrine dysregulation is causal, consequent, or an epiphenomenon of the disorder. Nonetheless, given the interindividual variation in the effectiveness of existing biological and psychological treatments, the need for novel treatment strategies such as those which target the HPA axis is clear.

Peripheral and central mechanisms of fatigue in inflammatory and noninflammatory rheumatic diseases

Fatigue is a common symptom in a large number of medical and psychological disorders, including many rheumatologic illnesses. A frequent question for health care providers is related to whether reported fatigue is "in the mind" or "in the body"-that is, central or peripheral. If fatigue occurs at rest without any exertion, this suggests psychological or central origins. If patients relate their fatigue mostly to physical activities, including exercise, their symptoms can be considered peripheral. However, most syndromes of fatigue seem to depend on both peripheral and central mechanisms. Sometimes, muscle biopsy with histochemistry may be necessary for the appropriate tissue diagnosis, whereas serological tests generally provide little reliable information about the origin of muscle fatigue. Muscle function and peripheral fatigue can be quantified by contractile force and action potential measurements, whereas validated questionnaires are frequently used for assessment of mental fatigue. Fatigue is a hallmark of many rheumatologic conditions, including fibromyalgia, myalgic encephalitis/chronic fatigue syndrome, rheumatoid arthritis, systemic lupus, Sjogren's syndrome, and ankylosing spondylitis. Whereas many studies have focused on disease activity as a correlate to these patients' fatigue, it has become apparent that other factors, including negative affect and pain, are some of the most powerful predictors for fatigue. Conversely, sleep problems, including insomnia, seem to be less important for fatigue. There are several effective treatment strategies available for fatigued patients with rheumatologic disorders, including pharmacological and nonpharmacological therapies.

From stress to functional syndromes: an internist's point of view

In this brief review we address schematically the relationship between two emerging issues in clinical medicine: stress and functional syndromes. It is becoming increasingly clear that they demand a multidimensional approach, considering simultaneously elements of behavioral therapy with traditional pharmacological treatment, guided by a better physiopathological understanding including autonomic assessment. New techniques, based on innovative analysis of continuous segments of electrocardiogram and non invasive arterial pressure recordings capable to extract hidden oscillations, provide quantitative indices of sympathetic and vagal modulation of the cardiovascular system. This more complete diagnostic process facilitates explanation of symptoms and reassurance of patients, based on functional evidence. The described clinical approach implies in addition an active collaboration of patients requiring the implementation of a creative alliance. Physical exercise, eating habits and muscular-mental relaxation are combined with pharmacological tools as needed.

Systematic review: fatigue in inflammatory bowel disease

BACKGROUND

Fatigue is common, disabling yet underappreciated, in patients with chronic diseases, including inflammatory bowel disease (IBD).

AIMS

To examine the literature and determine the prevalence and patterns of fatigue in IBD patients, to identify opportunities and directions for future research in this area.

METHODS

A systematic review using PubMed and Ovid Medline databases was conducted using search terms 'fatigue', 'Crohn', 'colitis' and 'inflammatory bowel disease'. A review of fatigue in other similar chronic diseases was also performed.

RESULTS

Ten studies were found to include data on fatigue in IBD patients; all were conducted between 1999 and 2009. However, only one study (in children) measured fatigue in IBD patients as a primary outcome. In patients in remission, the prevalence of fatigue in IBD patients ranges from 41 to 48%. Data are sparse and conflicting on whether fatigue severity is proportional to disease severity/activity.

CONCLUSIONS

Despite the clinical reality of fatigue, there are few published studies examining fatigue in IBD as a primary outcome. More data are needed on the prevalence, correlation between disease activity and fatigue severity, and putative pathogenic pathways involved in fatigue pathogenesis, before ultimately elucidating targeted therapies for fatigue in IBD patients.

Fatigue in liver disease: pathophysiology and clinical management

Fatigue is the most commonly encountered symptom in patients with liver disease, and it has a significant impact on their quality of life. However, although some progress has been made with regard to the understanding of the processes which may generate fatigue in general, the underlying cause(s) of liver disease-associated fatigue remain incompletely understood. The present review describes recent advances which have been made in our ability to measure fatigue in patients with liver disease in the clinical setting, as well as in our understanding of potential pathways which are likely important in the pathogenesis of fatigue associated with liver disease. Specifically, experimental findings suggest that fatigue associated with liver disease likely occurs as a result of changes in neurotransmission within the brain. In conclusion, a reasonable approach to help guide in the management of the fatigued patient with liver disease is presented.

5-hydroxytryptamine release in the anterior hypothalamic and the hippocampal areas of cholestatic rats

Cholestasis contributes to the genesis of fatigue through several mechanisms. Among these mechanisms, affected serotonergic neurotransmission is important in the pathogenesis of central fatigue. Previously, elevated levels of 5-hydroxyindole acetic acid (5-HIAA), the metabolite of 5-hydroxytryptamine (5-HT) and increased 5-HT(2) receptor density were demonstrated in the anterior hypothalamus and in the hippocampus of bile duct resected rats (BDR), respectively. The aim of this paper is to demonstrate evoked 5-HT release in selected brain regions like anterior hypothalamus and hippocampal CA1 regions of cholestatic rats using BDR rats as an experimental model for cholestasis. In this study, we analyzed the K+ evoked 5-HT and its metabolite 5-HIAA levels by using HPLC with electrochemical detection in the microdialysis samples collected from anterior hypothalamic and hippocampal CA1 regions of sham-operated and BDR rats (n = 6). The ratios of [5-HIAA] to [5-HT] following perfusion with 100 mM K+ artificial cerebrospinal fluid was used for the comparison of the evoked release of 5-HT. Locomotor activity was used to assess the signs of cholestasis associated fatigue in the BDR rats. The vertical and horizontal activity counts within 15 min were found to be decreased in the BDR rats compared to sham-operated rats (p < 0.05). Besides, the number of fecal boli (an index of emotionality) was also significantly fewer in the cholestatic rats (p < 0.05). No significant difference between the sham-operated and the BDR rats was detected in the basal 5-HT and 5-HIAA levels of anterior hypothalamus. K+ stimulation yielded a more profound increase in the [5-HIAA]/[5-HT] in the BDR rats (p < 0.05). The basal levels of 5-HT in CA1 region of the BDR rats was found to be lower than that of sham-operated group (p < 0.05), but no significant difference was observed in terms of evoked 5-HT release in both sham-operated and BDR rats. These findings imply the presence of affected serotonergic system in cholestasis.

CFSUM1 and CFSUM2 in urine from patients with chronic fatigue syndrome are methodological artefacts

McGregor et al. reported increased levels of an unidentified urinary compound (CFSUM1) in patients with chronic fatigue syndrome (CFS), with reduced excretion of another unidentified compound (CFSUM2), and suggested the possibility of chemical or metabolic 'markers' for CFS. The identity of CFSUM1 as reported was erroneous and the identities of these compounds have remained unknown until now. Urine samples were obtained from 30 patients with ME/CFS, 30 age- and sex-matched healthy controls, 20 control patients with depression and 22 control patients with rheumatoid arthritis. Samples were prepared using the published methods of McGregor et al. to produce heptafluorobutyryl-isobutyl derivatives of urinary metabolites. Alternative preparations utilised isopropyl, n-butyl and trifluoroacetyl derivatives. These were separated and identified using gas chromatography-mass spectrometry. CFSUM2 was identified as being partially derivatised [isobutyl ester-mono-heptafluorobutyryl (HFB)] serine. CFSUM1 was identified as partially derivatised pyroglutamic acid, being the isobutyl ester without formation of a HFB derivative. Both CFSUM1 and CFSUM2 are artefacts of the sample preparation procedure and previously reported quantitative abnormalities of CFSUM1 and CFSUM2 in urine from patients with ME/CFS are also artefactual. Pyroglutamic acid may be of primarily dietary origin. The methods used cannot provide reliable qualitative or quantitative data on urinary metabolites. No clinical or biochemical significance can be drawn between these compounds in ME/CFS or any other clinical conditions.

Antioxidant and DNA protecting properties of anti-fatigue herb Trichopus zeylanicus

Chronic fatigue is considered a complex symptom for which currently there is no curative treatment available. Oxidative stress plays an important role in the etiology of fatigue and antioxidant treatment might be a valuable therapeutic approach. The Kani, a tribal high altitude living population in southern India, traditionally use the seeds of Trichopus zeylanicus to combat fatigue. In this study, the antioxidant properties of Trichopus zeylanicus were established on free radicals (DPPH and ABTS), its ability to reduce iron, lipoxygenase activity and hydrogen peroxide-induced lipid peroxidation. The effects of Trichopus zeylanicus on reactive oxygen species induced plasmid DNA (pBR322) cleavage were also investigated. Trichopus zeylanicus significantly scavenged free radicals, reduced lipid peroxidation and inhibited lipoxygenase activity. Trichopus zeylanicus also exhibited iron-chelating activity and inhibited reactive oxygen species induced DNA damage. Trichopus zeylanicus contains NADH, polyphenols and sulfhydryl compounds, which have the ability to scavenge reactive oxygen species suggesting that the antioxidant activity may be an important mechanism of action of Trichopus zeylanicus to combat fatigue.

Plasma and urinary carnitine and acylcarnitines in chronic fatigue syndrome

Contradictory reports have suggested that serum free carnitine and acylcarnitine concentrations are decreased in patients with chronic fatigue syndrome (CFS) and that this is a cause of the muscle fatigue observed in these patients. Others have shown normal serum free carnitine and acylcarnitines in similar patients. We report here studies on free, total and esterified (acyl) carnitines in urine and blood plasma from UK patients with CFS and three control groups. Plasma and timed urine samples were obtained from 31 patients with CFS, 31 healthy controls, 15 patients with depression and 22 patients with rheumatoid arthritis. Samples were analysed using an established radioenzymatic procedure for total, free and esterified (acyl) carnitine. There were no significant differences in plasma or urinary total, free or esterified (acyl) carnitine between UK patients with CFS and the control groups or in renal excretion rates of these compounds. The data presented here show that, in the CFS patients studied, there are no significant abnormalities of free or esterified (acyl) carnitine. It is thus unlikely that abnormalities in carnitine homeostasis have any significant role in the aetiology of their chronic fatigue.

Urinary and plasma organic acids and amino acids in chronic fatigue syndrome

Previous work by others have suggested the occurrence of one or more chemical or metabolic 'markers' for ME/CFS including specific amino acids and organic acids and a number of unidentified compounds (CFSUM1, CFSUM2). We have shown elsewhere that CFSUM1 is partially derivatised pyroglutamic acid and CFSUM2 partially derivatised serine and have suggested and demonstrated that the analytical methods used were unsuitable to identify or to accurately quantify urinary metabolites. We have now made a detailed analysis of plasma and urinary amino acids and of urinary organic acids from patients with ME/CFS and from three control groups. Fasting blood plasma and timed urine samples were obtained from 31 patients with CFS, 31 age and sex-matched healthy controls, 15 patients with depression and 22 patients with rheumatoid arthritis. Plasma and urinary amino acids and urinary organic acids were determined using established and validated methods and data compared by statistical analysis. None of the previously reported abnormalities in urinary amino acids or of organic acids could be confirmed. Results however provide some evidence in patients with ME/CFS for underlying inflammatory disease and for reduced intramuscular collagen with a lowered threshold for muscle micro-injury. These factors in combination may provide a basis for the fatigue and muscle pain that are the major symptoms in these patients.

Heterogeneity of serum tryptophan concentration and availability to the brain in patients with the chronic fatigue syndrome

We assessed the serotonin status of patients with the chronic fatigue syndrome (CFS). Tryptophan (Trp) availability to the brain, expressed as the ratio of concentration of serum Trp to the sum of those of its five competitors (CAA), and other parameters of Trp disposition were compared in 23 patients with the CFS and 42 healthy controls. The serum [free Trp]/[CAA] ratio was 43% higher in CFS patients, due to a 48% higher [free Trp]. [Total Trp] was also significantly higher (by 19%) in CFS patients, and, although the [total Trp]/[CAA] ratio did not differ significantly between the control and patient groups, the difference became significant when the results were co-varied with age and gender. [CAA] was not significantly different between groups, but was significantly lower in females, compared to males, of the CFS patient group. We have established normal ranges for Trp disposition parameters and propose criteria for defining the serotonin-biosynthetic status in humans. We have provisionally identified two subgroups of CFS patients, one with normal serotonin and the other with a high serotonin status. The relevance of our findings to, and their implications for, the pharmacological and other therapies of the chronic fatigue syndrome are discussed.

Effect of paroxetine hydrochloride (Paxil�) on fatigue and depression in breast cancer patients receiving chemotherapy

BACKGROUND

Fatigue can significantly interfere with a cancer patient's ability to fulfill daily responsibilities and enjoy life. It commonly co-exists with depression in patients undergoing chemotherapy, suggesting that administration of an antidepressant that alleviates symptoms of depression could also reduce fatigue.

METHODS

We report on a double-blind clinical trial of 94 female breast cancer patients receiving at least four cycles of chemotherapy randomly assigned to receive either 20 mg of the selective serotonin re-uptake inhibitor (SSRI) paroxetine (Paxil, SmithKline Beecham Pharmaceuticals) or an identical-appearing placebo. Patients began their study medication seven days following their first on-study treatment and continued until seven days following their fourth on-study treatment. Seven days after each treatment, participants completed questionnaires measuring fatigue (Multidimensional Assessment of Fatigue, Profile of Mood States-Fatigue/Inertia subscale and Fatigue Symptom Checklist) and depression (Profile of Mood States-Depression subscale [POMS-DD] and Center for Epidemiologic Studies-Depression [CES-D]).

RESULTS

Repeated-measures ANOVAs, after controlling for baseline measures, showed that paroxetine was more effective than placebo in reducing depression during chemotherapy as measured by the CES-D (p = 0.006) and the POMS-DD (p = 0.07) but not in reducing fatigue (all measures, ps > 0.27).

CONCLUSIONS

Although depression was significantly reduced in the 44 patients receiving paroxetine compared to the 50 patients receiving placebo, indicating that a biologically active dose was used, no significant differences between groups on any of the measures of fatigued were observed. Results suggest that modulation of serotonin may not be a primary mechanism of fatigue related to cancer treatment.

Effect of bojungikki-tang on lipopolysaccharide-induced cytokine production from peripheral blood mononuclear cells of chronic fatigue syndrome patients

Bojungikki-tang (BIT) has been widely used to treat patients suffering from chronic fatigue syndrome (CFS). However, its effect has not been yet investigated experimentally. Based upon the clinical presentation of CFS, we hypothesized that cytokines may play a role in the pathogenesis of the disease. We studied the effect of BIT on lipopolysaccharide (LPS)-induced various cytokines production in peripheral blood mononuclear cells (PBMC) of CFS patients. Bojungikki-tang (1 mg/mL) significantly inhibited LPS-induced tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-10, transforming growth factor (TGF)-beta1 production by 63.55% +/- 0.19%, 55.06% +/- 0.27%, 48.23% +/- 0.48%, 54.09% +/- 0.76%, respectively (P < 0.05). Bojungikki-tang showed a slightly lower inhibitory effect of LPS-induced Interferon (IFN)-gamma production. These results suggest that BIT may be useful in treating fatigue associated with chronic diseases.

Association between serotonin transporter gene polymorphism and chronic fatigue syndrome

Interaction between the hypothalamo-pituitary-adrenal axis and the serotonergic system is thought to be disrupted in chronic fatigue syndrome (CFS) patients. We examined a serotonin transporter (5-HTT) gene promoter polymorphism, which affects the transcriptional efficiency of 5-HTT, in 78 CFS patients using PCR amplification of the blood genomic DNA. A significant increase of longer (L and XL) alleic variants was found in the CFS patients compared to the controls both by the genotype-wise and the allele-wise analyses (both p<0.05, by chi(2) test and Fisher's exact test). Attenuated concentration of extracellular serotonin due to longer variants may cause higher susceptibility to CFS.

Effect of Kuibitang on lipopolysaccharide-induced cytokine production in peripheral blood mononuclear cells of chronic fatigue syndrome patients

Kuibitang (KBT) is clinically used to treat patients suffering from chronic fatigue syndrome (CFS) in South Korea. However, its effect has not been investigated experimentally. Recent reports have shown that CFS patients display an altered cytokine production. We examined the effect of KBT on lipopolysaccharide (LPS)-induced various cytokines production in peripheral blood mononuclear cells (PBMC) of CFS patients and healthy controls. KBT (1 mg/ml) significantly inhibited LPS-induced tumor necrosis factor-alpha, interleukin-10, and transforming growth factor-beta1 production in PBMC of CFS patients. However, LPS-induced interferon-gamma production was significantly increased by KBT (0.01 mg/ml). These results provide evidence of a novel activity of the KBT that regulate cytokines production related with CFS.

Differential Effects of Paroxetine on Fatigue and Depression: A Randomized, Double-Blind Trial From the University of Rochester Cancer Center Community Clinical Oncology Program

Purpose: Fatigue and depression typically occur together in cancer patients, suggesting a common etiology, perhaps based on serotonin. This randomized clinical trial tested whether paroxetine, a selective serotonin reuptake inhibitor antidepressant known to modulate brain serotonin, would reduce fatigue in cancer patients and whether any reduction was related to depression.

Patients and Methods: Cancer patients undergoing chemotherapy for the first time were assessed for fatigue. Of 704 patients who reported fatigue at their second chemotherapy cycle, 549 patients were randomly assigned to receive either 20 mg of oral paroxetine hydrochloride daily or placebo for 8 weeks. The assessments of fatigue and depression were performed at cycles 3 and 4 of chemotherapy.

Results: A total of 244 patients treated with paroxetine and 235 patients treated with placebo provided assessable data. No difference was detected in fatigue between patient groups. At the end of the study, there was a difference between groups in the mean level of depression (Center for Epidemiologic Studies Depression scores, 12.0 v 14.8, respectively; P < .01).

Conclusion: Paroxetine had no influence on fatigue in patients receiving chemotherapy. A possible explanation is that cancer-related fatigue does not involve a reduction in brain 5-HT levels.

Fibromyalgia, fatigue, and headache disorders

Fibromyalgia, chronic fatigue, and primary headaches are common and debilitating disorders, and their related symptoms of widespread pain, fatigue, and headache have complex interactions and different implications for classification, diagnosis, mechanisms, and treatment. The "continuum" or "spectrum" idea and the modular headache theory are fundamental concepts in understanding these interactions. The overlap between symptom-based conditions leads the reasons to consider them as "functional somatic syndromes." Management of these patients includes a correct diagnosis, appropriate investigation for associated conditions, adequate treatment, and considering the therapeutic opportunities and limitations the comorbid disorders may impose.

Fatigue in chronic migraine patients

Fatigue is a common symptom frequently reported in many disorders including headaches, but little is known about its nature. The objective was to determine the prevalence of fatigue in chronic migraine (CM) patients, to define its subtypes and its relationship with other conditions comorbid with CM. Sixty-three CM patients were analysed. The Fatigue Severity Scale (FSS), the Chalder fatigue scale and the CDC diagnostic criteria for chronic fatigue syndrome (CFS) were used. Fifty-three (84.1%) patients had FSS scores greater than 27. Forty-two (66.7%) patients met the CDC criteria for CFS. Thirty-two patients (50.8%) met the modified CDC criteria (without headache). Beck depression scores correlated with FSS, mental and physical fatigue scores. Trait anxiety scores also correlated with fatigue scales. Women had higher FSS scores than men, P < 0.05. Physical fatigue was associated with fibromyalgia, P < 0.05. Fatigue as a symptom and CFS as a disorder are both common in CM patients. Therapeutic interventions include a graded aerobic exercise program, cognitive behavioural therapy and antidepressants. Identification of fatigue and its subtypes in headache disorders and recognition of headaches in CFS patients has implications for the pathophysiology, diagnosis and treatment of these disorders.

Therapy of circadian rhythm disorders in chronic fatigue syndrome: no symptomatic improvement with melatonin or phototherapy

BACKGROUND

Patients with chronic fatigue syndrome (CFS) show evidence of circadian rhythm disturbances. We aimed to determine whether CFS symptoms were alleviated by melatonin and bright-light phototherapy, which have been shown to improve circadian rhythm disorders and fatigue in jet-lag and shift workers.

DESIGN

Thirty patients with unexplained fatigue for > 6 months were initially assessed using placebo and then received melatonin (5 mg in the evening) and phototherapy (2500 Lux for 1 h in the morning), each for 12 weeks in random order separated by a washout period. Principal symptoms of CFS were measured by visual analogue scales, the Shortform (SF-36) Health Survey, Mental Fatigue Inventory and Hospital Anxiety and Depression Scale. We also determined the circadian rhythm of body temperature, timing of the onset of melatonin secretion, and the relationship between these.

RESULTS

Neither intervention showed any significant effect on any of the principal symptoms or on general measures of physical or mental health. Compared with placebo, neither body temperature rhythm nor onset of melatonin secretion was significantly altered by either treatment, except for a slight advance of temperature phase (0.8 h; P = 0.04) with phototherapy.

CONCLUSION

Melatonin and bright-light phototherapy appear ineffective in CFS. Both treatments are being prescribed for CFS sufferers by medical and alternative practitioners. Their unregulated use should be prohibited unless, or until, clear benefits are convincingly demonstrated.

Fatigue in cholestatic liver disease--a perplexing symptom

Fatigue is an important symptom and a quality of life determinant in patients with cholestatic liver disease. The pathogenesis of fatigue is obscure, although alterations in central neurotransmission and peripheral muscle dysfunction have been incriminated. No effective treatment is available at present. The available literature on fatigue in cholestatic liver disease is reviewed.

LPS-induced IL-10 production in whole blood cultures from chronic fatigue syndrome patients is increased but supersensitive to inhibition by dexamethasone

Several causes have been held responsible for the chronic fatigue syndrome (CFS), including an altered hypothalamus-pituitary-adrenal gland (HPA)-axis activity, viral infections and a reduced Th1 activity. Therefore, it was investigated whether the regulation of IL-10 is different in CFS. LPS-induced cytokine secretion in whole blood cultures showed a significant increase in IL-10 and a trend towards a decrease in IL-12 as compared with healthy controls. In patients and controls, IL-12 secretion was equally sensitive to suppression by dexamethasone, whereas IL-10 secretion appeared more sensitive in CFS-patients. In controls, IL-10 and IL-12 secretion were inversely correlated with free serum cortisol (r=-0.492, p<0.02 and r=-0.434, p<0.05, respectively). In CFS, such an inverse correlation was found for IL-12 (r=-0.611, p<0.02) but not for IL-10 (r=-0.341, ns). These data are suggestive for a disturbed glucocorticoid regulation of IL-10 in CFS.

Altered glucocorticoid regulation of the immune response in the chronic fatigue syndrome

It is increasingly recognized that glucocortiocoids (GCs) can have subtle modulatory effects in immunoregulation rather than having generalized immunosuppressive effects. GCs suppress Th1 cells and cellular immunity, but may favor Th2 responses and humoral immunity. The chronic fatigue syndrome (CFS) appears to be associated with a disturbed HPA-axis. Moreover, CFS patients show several immunological changes suggestive of decreased cellular immunity. It is postulated herein that in CFS patients a decreased Th1/Th2 balance may be the result of selective effects of GC on the IL-10/IL-12 regulatory circuit.

Increased sensitivity to glucocorticoids in peripheral blood mononuclear cells of chronic fatigue syndrome patients, without evidence for altered density or affinity of glucocorticoid receptors

BACKGROUND

In this study we tested the hypothesis that the increased sensitivity to glucocorticoids in chronic fatigue syndrome (CFS)-patients can be attributed to an altered functioning of their glucocorticoid receptors (GR).

METHODS

For this purpose, affinity and distribution of the GR were studied in purified, peripheral blood mononuclear cells (PBMC) of 10 CFS patients and 14 controls along with the responsiveness of these cells to glucocorticoids in vitro.

RESULTS

Affinity (Kd) and number of GR was not different in PBMC of CFS patients when compared with the controls (Kd, 12.9 +/- 8.9 nmol vs 18.8 +/- 16.2 nmol and GR number, 4,839 +/- 2,824/ cell vs 4,906 +/- 1,646/cell). Moreover, RT-PCR revealed no differences in GR messenger RNA expression. Nevertheless, PBMC from CFS patients showed an increased sensitivity to glucocorticoids in vitro. In CFS patients 0.01 micromol dexamethasone suppressed PBMC proliferation by 37%, whereas the controls were only suppressed by 17% (P < 0.01). Addition of phorbol 12-myristate 13-acetate to the cultures rendered the cells resistant to dexamethasone with regard to proliferation and IL-10 and IFN-gamma production, but not to IL-2 and TNF-alpha production in both patients and controls. No difference between patients and controls was observed in this respect

CONCLUSIONS

In conclusion, PBMC of CFS patients display an increased sensitivity to glucocorticoids, which cannot be explained by number or affinity of the GR but should rather be attributed to molecular processes beyond the actual binding of the ligand to the GR.

Chronic fatigue syndrome: reviewing the research findings

This article reviews the current state of research in chronic fatigue syndrome (CFS). The evolving definition, prevalence, and prognosis of this controversial illness are presented. We review studies examining psychiatric, personality, and psychosocial etiology for CFS. The evidence for pathophysiology in CFS is also presented, and studies investigating viral, immune, neuroimaging, neuroendocrine, and central and autonomic nervous system abnormalities in CFS are assessed. Current evidence indicates that CFS is multi-determined and heterogeneous and that subgrouping patients according to factors such as psychiatric state and symptom onset may be fruitful. The current state of treatment for CFS is reviewed, and the challenges for research aimed at resolving this prototypical mind/body problem are discussed.

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.

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.

Neurocognitive functioning in chronic fatigue syndrome

Although substantial research has been conducted on chronic fatigue syndrome (CFS) over the past decade, the syndrome remains poorly understood. The most recent case definition describes CFS as being characterized both by disabling fatigue and by subjective reports of difficulty with concentration and "short-term" memory. However, research into the neurocognitive and psychological functioning of individuals with CFS has provided mixed objective results. The current paper reviews studies that have examined the neurocognitive and/or psychological functioning of individuals with CFS. Changes in research design and instruments employed to study individuals with CFS are suggested.

The rise and fall of the chronic fatigue syndrome as defined by Holmes et al

This paper is a sequel to my monograph on neurocirculatory asthenia and chronic fatigue syndrome. It pays special attention to the nature of chronic fatigue syndrome, to the forms of neurocirculatory asthenia, and above all to the 6th form in which profound fatigue is the dominant symptom. All forms including the 6th are characterized by the presence of concomitant symptoms due to dysfunction of the autonomic nervous system. Chronic fatigue syndrome as defined by Holmes et al is devoid of these symptoms. Up till the present day no case histories of it have been published. It is argued that chronic fatigue syndrome sensu Holmes et al does not exist, the 6th form of neurocirculatory asthenia having to take up its place.

Vagal tone is reduced during paced breathing in patients with the chronic fatigue syndrome

Patients with chronic fatigue syndrome (CFS) often complain of an inability to maintain activity levels and a variety of autonomic-like symptoms that make everyday activity intolerable at times. The purpose of the study was to determine if there were differences in vagal activity at fixed breathing rates in women with CFS. Twelve women with the diagnosis of CFS between the ages of 32 and 59 years volunteered for the study. Healthy women, who were between the ages of 30 and 49, served as controls. Full signal electrocardiograph and respiratory signals were collected during a paced breathing protocol of three fixed breathing rates (8, 12 and 18 breaths/min) performed in the sitting and standing postures. Vagal activity was analyzed by means of heart rate spectral analysis to determine the subject's response to specific breathing rates and postures. Heart rate variability was used as a non-invasive method of measuring the parasympathetic component of the autonomic nervous system. Using this method, although there was significantly less vagal power in the sitting versus the standing postures for both groups, the overall vagal power was significantly lower (p < 0.034) in the CFS group versus healthy controls. Vagal power was also significantly lower (p < 0.01 to p < 0.05) at all breathing rates in both postures except while standing and breathing at 18 breaths/min. Knowledge of the differences in vagal activity for CFS patients may allow stratification for the analysis of other research variables.