Enhanced feedback sensitivity to prednisolone in chronic fatigue syndrome

Research progress in the treatment of chronic fatigue syndrome through interventions targeting the hypothalamus-pituitary-adrenal axis

Chronic fatigue syndrome (CFS) causes great harm to individuals and society. Elucidating the pathogenesis of CFS and developing safe and effective treatments are urgently needed. This paper reviews the functional changes in the hypothalamus-pituitary-adrenal (HPA) axis in patients with CFS and the associated neuroendocrine mechanisms. Despite some controversy, the current mainstream research evidence indicates that CFS patients have mild hypocortisolism, weakened daily variation in cortisol, a weakened response to the HPA axis, and an increase in negative feedback of the HPA axis. The relationship between dysfunction of the HPA axis and the typical symptoms of CFS are discussed, and the current treatment methods are reviewed.

Utility of salivary cortisol profile as a predictive biomarker in nurses' turnover risk: a preliminary study

BACKGROUND

Predicting nurse turnover risk is crucial due to the global nursing shortage; however, existing predictors, such as fatigue and burnout, lack objectivity. Salivary cortisol is a non-invasive marker of stress and fatigue, but its utility in predicting nurse turnover risk is unknown. We examined whether salivary cortisol profiles across three different day shifts in a month are predictors of the extent of nurses' reluctance to stay in their current jobs.

METHODS

This preliminary longitudinal study followed forty female nurses who engaged in shift work at a university hospital for 3 months. Data at enrollment were collected including demographics, working conditions, chronic fatigue (the Japanese version of the Occupational Fatigue/Exhaustion Recovery Scale), and burnout (Japanese Burnout scale). Salivary cortisol was measured before the three different day shifts (after awakening) during the first month, and the means of these measurements were used as the cortisol profile. The extent of reluctance to stay was assessed using the numerical rating scale at 3 months.

RESULTS

Among the forty female nurses (mean [SD] age, 28.3 [5.1]), all completed follow-up and were included in the analysis. The cortisol profile was associated with the extent of reluctance to stay (P = 0.017), and this association was significant despite adjustments for chronic fatigue and burnout (P = 0.005). A multiple regression model with chronic fatigue, burnout, and job tenure explained 41.5% of the variation in reluctance to stay. When the cortisol profile was added to this model, the association of the cortisol profile was significant (P = 0.006) with an R2 of 0.529 (ΔR2 = 0.114).

CONCLUSIONS

This preliminary study conducted in an actual clinical setting indicated the potential of the salivary cortisol profile across three different day shifts in a month to predict nurses' reluctance to stay in their current jobs. The combination of subjective indicators and the cortisol profile would be useful in predicting nurses' turnover risk.

A systematic review and meta-analysis of urinary biomarkers in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)

BACKGROUND

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a multifactorial illness that affects many body systems including the immune, nervous, endocrine, cardiovascular, and urinary systems. There is currently no universal diagnostic marker or targeted treatment for ME/CFS. Urine is a non-invasive sample that provides biomarkers that may have the potential to be used in a diagnostic capacity for ME/CFS. While there are several studies investigating urine-based biomarkers for ME/CFS, there are no published systematic reviews to summarise existing evidence of these markers. The aim of this systematic review was to compile and appraise literature on urinary-based biomarkers in ME/CFS patients compared with healthy controls.

METHODS

Three databases: Embase, PubMed, and Scopus were searched for articles pertaining to urinary biomarkers for ME/CFS compared with healthy controls published between December 1994 to December 2022. The final articles included in this review were determined through application of specific inclusion and exclusion criteria. Quality and bias was assessed using the Joanna Briggs Institute Critical Appraisal Checklist for Case Control Studies. A meta-analysis according to Cochrane guidelines was conducted on select studies, in particular, those that investigate urinary free cortisol levels in ME/CFS patients compared to healthy controls using the program STATA 17.

RESULTS

Twenty-one studies were included in this review. All of the studies investigated urinary-based markers in ME/CFS patients compared with healthy controls. The reported changes in urinary outputs include urinary free cortisol (38.10%), carnitine (28.6%), iodine (4.76%), and the metabolome (42.86%). In most cases, there was minimal overlap in the main outcomes measured across the studies, however, differences in urinary free cortisol between ME/CFS patients and healthy controls were commonly reported. Seven studies investigating urinary free cortisol were included in the meta-analysis. While there were significant differences found in urinary free cortisol levels in ME/CFS patients, there was also substantial heterogeneity across the included studies that makes drawing conclusions difficult.

CONCLUSIONS

There is limited evidence suggesting a consistent and specific potential urinary-based biomarker for ME/CFS. Further investigations using more standardised methodologies and more stringent case criteria may be able to identify pathophysiological differences with diagnostic potential in ME/CFS patients compared with healthy controls.

ME/CFS and Long COVID share similar symptoms and biological abnormalities: road map to the literature

Some patients remain unwell for months after "recovering" from acute COVID-19. They develop persistent fatigue, cognitive problems, headaches, disrupted sleep, myalgias and arthralgias, post-exertional malaise, orthostatic intolerance and other symptoms that greatly interfere with their ability to function and that can leave some people housebound and disabled. The illness (Long COVID) is similar to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) as well as to persisting illnesses that can follow a wide variety of other infectious agents and following major traumatic injury. Together, these illnesses are projected to cost the U.S. trillions of dollars. In this review, we first compare the symptoms of ME/CFS and Long COVID, noting the considerable similarities and the few differences. We then compare in extensive detail the underlying pathophysiology of these two conditions, focusing on abnormalities of the central and autonomic nervous system, lungs, heart, vasculature, immune system, gut microbiome, energy metabolism and redox balance. This comparison highlights how strong the evidence is for each abnormality, in each illness, and helps to set priorities for future investigation. The review provides a current road map to the extensive literature on the underlying biology of both illnesses.

[Diagnosis and treatment of early forms of cognitive impairment: possibilities of influencing neuronal energy metabolism. Resolution of the Council of Experts]

Diagnosis and treatment of early forms of cognitive impairment: possibilities of influencing neuronal energy metabolism. Resolution of the Council of Experts.

Increased risk of chronic fatigue syndrome following psoriasis: a nationwide population-based cohort study

BACKGROUND

The onset of chronic fatigue syndrome (CFS) has been shown to be associated with several immunological conditions such as infections or atopy. The aim of this study was to clarify the risk of chronic fatigue syndrome following the diagnosis of psoriasis, an immune-related dermatological disease, by analyzing the National Health Insurance Research Database of Taiwan.

METHOD

2616 patients aged 20 years or older with newly diagnosed psoriasis during 2004-2008 and 10,464 participants without psoriasis were identified. Both groups were followed up until the diagnoses of CFS were made at the end of 2011.

RESULTS

The relationship between psoriasis and the subsequent risk of CFS was estimated through Cox proportional hazards regression analysis, with the incidence density rates being 2.27 and 3.58 per 1000 person-years among the non-psoriasis and psoriasis populations, respectively (adjusted hazard ratio [HR] = 1.48, with 95% confidence interval [CI] 1.07-2.06). In the stratified analysis, the psoriasis group were consistently associated with a higher risk of CFS in male sex (HR = 2.05, 95% CI 1.31-3.20) and age group of ≥ 60 years old (HR = 2.32, 95% CI 1.33-4.06). In addition, we discovered that the significantly increased risk of CFS among psoriasis patients is attenuated after they receive phototherapy and/or immunomodulatory drugs.

CONCLUSIONS

The data from this population-based retrospective cohort study revealed that psoriasis is associated with an elevated risk of subsequent CFS, which is differentiated by sex and age.

Hair and salivary cortisol in a cohort of women with chronic fatigue syndrome

Hypocortisolism has been found in CFS patients in blood, urine, and saliva. It is unclear if hypocortisolism can also be demonstrated using long-term cortisol measurements, such as cortisol in hair. In addition, the interaction between the HPA axis and the immune system, both expected to play an important role in CFS, is unclear. The objective of the current study was to compare hair and salivary cortisol concentrations in a cohort of female CFS patients to those in healthy controls, and to test the effect of an interleukin-1 receptor antagonist (anakinra) on the HPA axis. Salivary cortisol concentrations of 107 CFS patients were compared to 59 healthy controls, with CFS patients showing a decreased cortisol awakening response (4.2 nmol/L ± 5.4 vs 6.1 nmol/L ± 6.3, p = 0.036). Total cortisol output during the day did not differ significantly in saliva, but there was a trend to lower hair cortisol in a subset of 46 patients compared to 46 controls (3.8 pg/mg ± 2.1 vs 4.3 pg/mg ± 1.8, p = 0.062). After four weeks of treatment with either daily anakinra (100 mg/day) or placebo, there was a slight decrease of hair cortisol concentrations in the anakinra group compared to an increase in the placebo group (p = 0.022). This study confirms the altered dynamics of the HPA axis in a group of CFS patients, and for the first time shows that this might also be present for long-term cortisol measures.

Reduction of Glucocorticoid Receptor Function in Chronic Fatigue Syndrome

Glucocorticoid receptor (GR) function may have aetiopathogenic significance in chronic fatigue syndrome (CFS), via its essential role in mediating inflammatory responses as well as in hypothalamic-pituitary-adrenal axis regulation. GR function can be estimated ex vivo by measuring dexamethasone (dex) modulation of cytokine response to lipopolysaccharide (LPS), and in vivo using the impact of dex on cortisol levels. This study aimed to compare the GR function between CFS (n = 48), primary Sjögren's syndrome (a disease group control) (n = 27), and sedentary healthy controls (HCs) (n = 20), and to investigate its relationship with clinical measures. In the GR ex vivo response assay, whole blood was diluted and incubated with LPS (to stimulate cytokine production), with or without 10 or 100 nanomolar concentrations of dex. Cytometric bead array (CBA) and flow cytometry enabled quantification of cytokine levels (TNFα, interleukin- (IL-) 6, and IL-10) in the supernatants. In the in vivo response assay, five plasma samples were taken for determination of total cortisol concentration using ELISA at half-hourly intervals on two consecutive mornings separated by ingestion of 0.5 mg of dex at 11 pm. The association of the data from the in vivo and ex vivo analyses with reported childhood adversity was also examined. CFS patients had reduced LPS-induced IL-6 and TNFα production compared to both control groups and reduced suppression of TNFα by the higher dose of dex compared to HCs. Cortisol levels, before or after dex, did not differ between CFS and HCs. Cortisol levels were more variable in CFS than HCs. In the combined group (CFS plus HC), cortisol concentrations positively and ex vivo GR function (determined by dex-mediated suppression of IL-10) negatively correlated with childhood adversity score. The results do not support the hypothesis that GR dysregulation is aetiopathogenic in CFS and suggest that current and future endocrine cross-sectional studies in CFS may be vulnerable to the confounding influence of childhood trauma which is likely increased by comorbid depression.

CNS findings in chronic fatigue syndrome and a neuropathological case report

Chronic fatigue syndrome (CFS) is characterized as a persistent, debilitating complex disorder of unknown etiology, whereby patients suffer from extreme fatigue, which often presents with symptoms that include chronic pain, depression, weakness, mood disturbances, and neuropsychological impairment. In this mini review and case report, we address central nervous system (CNS) involvement of CFS and present neuropathological autopsy findings from a patient who died with a prior diagnosis of CFS. Among the most remarkable pathological features of the case are focal areas of white matter loss, neurite beading, and neuritic pathology of axons in the white matter with axonal spheroids. Atypical neurons displaying aberrant sprouting processes in response to injury are observed throughout cortical gray and white matter. Abundant amyloid deposits identical to AD plaques with accompanying intracellular granular structures are observed as well. Neurofibrillary tangles are also present in the white matter of the frontal cortex, thalamus and basal ganglia. Taken together, these neuropathological findings warrant further studies into CNS disease associated with CFS.

A users guide to HPA axis research

Glucocorticoid hormones (cortisol and corticosterone - CORT) are the effector hormones of the hypothalamic-pituitary-adrenal (HPA) axis neuroendocrine system. CORT is a systemic intercellular signal whose level predictably varies with time of day and dynamically increases with environmental and psychological stressors. This hormonal signal is utilized by virtually every cell and physiological system of the body to optimize performance according to circadian, environmental and physiological demands. Disturbances in normal HPA axis activity profiles are associated with a wide variety of physiological and mental health disorders. Despite numerous studies to date that have identified molecular, cellular and systems-level glucocorticoid actions, new glucocorticoid actions and clinical status associations continue to be revealed at a brisk pace in the scientific literature. However, the breadth of investigators working in this area poses distinct challenges in ensuring common practices across investigators, and a full appreciation for the complexity of a system that is often reduced to a single dependent measure. This Users Guide is intended to provide a fundamental overview of conceptual, technical and practical knowledge that will assist individuals who engage in and evaluate HPA axis research. We begin with examination of the anatomical and hormonal components of the HPA axis and their physiological range of operation. We then examine strategies and best practices for systematic manipulation and accurate measurement of HPA axis activity. We feature use of experimental methods that will assist with better understanding of CORT's physiological actions, especially as those actions impact subsequent brain function. This research approach is instrumental for determining the mechanisms by which alterations of HPA axis function may contribute to pathophysiology.

Hypothalamic-Pituitary-Adrenal Hypofunction in Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS) as a Consequence of Activated Immune-Inflammatory and Oxidative and Nitrosative Pathways

There is evidence that immune-inflammatory and oxidative and nitrosative stress (O&NS) pathways play a role in the pathophysiology of myalgic encephalomyelitis (ME)/chronic fatigue syndrome (CFS). There is also evidence that these neuroimmune diseases are accompanied by hypothalamic-pituitary-adrenal (HPA) axis hypoactivity as indicated by lowered baseline glucocorticoid levels. This paper aims to review the bidirectional communications between immune-inflammatory and O&NS pathways and HPA axis hypoactivity in ME/CFS, considering two possibilities: (a) Activation of immune-inflammatory pathways is secondary to HPA axis hypofunction via attenuated negative feedback mechanisms, or (b) chronic activated immune-inflammatory and O&NS pathways play a causative role in HPA axis hypoactivity. Electronic databases, i.e., PUBMED, Scopus, and Google Scholar, were used as sources for this narrative review by using keywords CFS, ME, cortisol, ACTH, CRH, HPA axis, glucocorticoid receptor, cytokines, immune, immunity, inflammation, and O&NS. Findings show that activation of immune-inflammatory and O&NS pathways in ME/CFS are probably not secondary to HPA axis hypoactivity and that activation of these pathways may underpin HPA axis hypofunction in ME/CFS. Mechanistic explanations comprise increased levels of tumor necrosis factor-α, T regulatory responses with elevated levels of interleukin-10 and transforming growth factor-β, elevated levels of nitric oxide, and viral/bacterial-mediated mechanisms. HPA axis hypoactivity in ME/CFS is most likely a consequence and not a cause of a wide variety of activated immune-inflammatory and O&NS pathways in that illness.

Glucocorticoid Fast Feedback Inhibition of Stress-Induced ACTH Secretion in the Male Rat: Rate Independence and Stress-State Resistance

Normal glucocorticoid secretion is critical for physiological and mental health. Glucocorticoid secretion is dynamically regulated by glucocorticoid-negative feedback; however, the mechanisms of that feedback process are poorly understood. We assessed the temporal characteristics of glucocorticoid-negative feedback in vivo using a procedure for drug infusions and serial blood collection in unanesthetized rats that produced a minimal disruption of basal ACTH plasma levels. We compared the negative feedback effectiveness present when stress onset coincides with corticosterone's (CORT) rapidly rising phase (30 sec pretreatment), high plateau phase (15 min pretreatment), or restored basal phase (60 min pretreatment) as well as effectiveness when CORT infusion occurs after the onset of stress (5 min poststress onset). CORT treatment prior to stress onset acted remarkably fast (within 30 sec) to suppress stress-induced ACTH secretion. Furthermore, fast feedback induction did not require rapid increases in CORT at the time of stress onset (hormone rate independent), and those feedback actions were relatively long lasting (≥15 min). In contrast, CORT elevation after stress onset produced limited and delayed ACTH suppression (stress state resistance). There was a parallel stress-state resistance for CORT inhibition of stress-induced Crh heteronuclear RNA in the paraventricular nucleus but not Pomc heteronuclear RNA in the anterior pituitary. CORT treatment did not suppress stress-induced prolactin secretion, suggesting that CORT feedback is restricted to the control of hypothalamic-pituitary-adrenal axis elements of a stress response. These temporal, stress-state, and system-level features of in vivo CORT feedback provide an important physiological context for ex vivo studies of molecular and cellular mechanisms of CORT-negative feedback.

Chronic Fatigue Syndrome and DNA Hypomethylation of the Glucocorticoid Receptor Gene Promoter 1F Region: Associations With HPA Axis Hypofunction and Childhood Trauma

OBJECTIVES

Chronic fatigue syndrome (CFS) has been associated with hypothalamic-pituitary-adrenal axis hypofunction and enhanced glucocorticoid receptor (GR) sensitivity. In addition, childhood trauma is considered a major risk factor for the syndrome. This study examines DNA methylation of the GR gene (NR3C1) in CFS and associations with childhood sexual and physical trauma.

METHODS

Quantification of DNA methylation within the 1F promoter region of NR3C1 was performed in 76 female patients (46 with no/mild and 30 with moderate/severe childhood trauma) and 19 healthy controls by using Sequenom EpiTYPER. Further, we examined the association of NR3C1-1F promoter methylation with the outcomes of the low-dose (0.5 mg) dexamethasone/corticotropin-releasing factor test in a subset of the study population. Mann-Whitney U tests and Spearman correlations were used for statistical analyses.

RESULTS

Overall NR3C1-1F DNA methylation was lower in patients with CFS than in controls. After cytosine guanine dinucleotide (CpG)-specific analysis, CpG_1.5 remained significant after Bonferroni correction (adjusted p = .0014). Within the CFS group, overall methylation (ρ = 0.477, p = .016) and selective CpG units (CpG_1.5: ρ = 0.538, p = .007; CpG_12.13: ρ = 0.448, p = .025) were positively correlated with salivary cortisol after dexamethasone administration. There was no significant difference in NR3C1-1F methylation between traumatized and nontraumatized patients.

CONCLUSIONS

We found evidence of NR3C1 promoter hypomethylation in female patients with CFS and the functional relevance of these differences was consistent with the hypothalamic-pituitary-adrenalaxis hypofunction hypothesis (GR hypersuppression). However, we found no evidence of an additional effect of childhood trauma on CFS via alterations in NR3C1 methylation.

Polymorphism in COMT is associated with IgG3 subclass level and susceptibility to infection in patients with chronic fatigue syndrome

BACKGROUND

Chronic fatigue syndrome (CFS) is considered as a neuroimmunological disease but the etiology and pathophysiology is poorly understood. Patients suffer from sustained exhaustion, cognitive impairment and an increased sensitivity to pain and sensory stimuli. A subset of patients has frequent respiratory tract infections (RRTI). Dysregulation of the sympathetic nervous system and an association with genetic variations in the catechol-O-methyltransferase (COMT) and glucocorticoid receptor genes influencing sympathetic and glucocorticoid metabolism were reported in CFS. Here, we analyzed the prevalence of SNPs of COMT and glucocorticoid receptor-associated genes in CFS patients and correlated them to immunoglobulin levels and susceptibility to RRTI.

METHODS

We analyzed blood cells of 74 CFS patients and 76 healthy controls for polymorphisms in COMT, FKBP5 and CRHR1 by allelic discrimination PCR. Serum immunoglobulins were determined by immunoturbidimetric technique, cortisol levels by ECLIA.

RESULTS

Contrary to previous reports, we found no difference between CFS patients and healthy controls in the prevalence of SNPs for COMT, FKBP5 and CRHR1. In patients with the Met/Met variant of COMT rs4680 we observed enhanced cortisol levels providing evidence for its functional relevance. Both enhanced IgE and diminished IgG3 levels and an increased susceptibility to RRTI were observed in CFS patients with the Met/Met variant. Such an association was not observed in 68 non-CFS patients with RRTI.

CONCLUSION

Our results indicate a relationship of COMT polymorphism rs4680 with immune dysregulation in CFS providing a potential link for the association between stress and infection susceptibility in CFS.

Accurate diagnosis of myalgic encephalomyelitis and chronic fatigue syndrome based upon objective test methods for characteristic symptoms

Although myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS) are considered to be synonymous, the definitional criteria for ME and CFS define two distinct, partially overlapping, clinical entities. ME, whether defined by the original criteria or by the recently proposed criteria, is not equivalent to CFS, let alone a severe variant of incapacitating chronic fatigue. Distinctive features of ME are: muscle weakness and easy muscle fatigability, cognitive impairment, circulatory deficits, a marked variability of the symptoms in presence and severity, but above all, post-exertional “malaise”: a (delayed) prolonged aggravation of symptoms after a minor exertion. In contrast, CFS is primarily defined by (unexplained) chronic fatigue, which should be accompanied by four out of a list of 8 symptoms, e.g., headaches. Due to the subjective nature of several symptoms of ME and CFS, researchers and clinicians have questioned the physiological origin of these symptoms and qualified ME and CFS as functional somatic syndromes. However, various characteristic symptoms, e.g., post-exertional “malaise” and muscle weakness, can be assessed objectively using well-accepted methods, e.g., cardiopulmonary exercise tests and cognitive tests. The objective measures acquired by these methods should be used to accurately diagnose patients, to evaluate the severity and impact of the illness objectively and to assess the positive and negative effects of proposed therapies impartially.

Gray matter volumes in patients with chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is a debilitating and complex disorder characterized by profound fatigue with uncertain pathologic mechanism. Neuroimage may be an important key to unveil the central nervous system (CNS) mechanism in CFS. Although most of the studies found gray matter (GM) volumes reduced in some brain regions in CFS, there are many factors that could affect GM volumes in CFS, including chronic pain, stress, psychiatric disorder, physical activity, and insomnia, which may bias the results. In this paper, through reviewing recent literatures, we discussed these interferential factors, which overlap with the symptoms of CFS.

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.

The neuropsychiatric and neuropsychological features of chronic fatigue syndrome: revisiting the enigma

The aim of this article is to provide a comprehensive and updated review of the key neuropsychiatric and neuropsychological complaints associated with chronic fatigue syndrome (CFS). Neuropsychiatric and neuropsychological difficulties are common in CFS and are linked primarily to disorders of mood, affect and behaviour. The neuropsychiatric complaint most frequently encountered amongst CFS patients is depression and in particular major depressive disorder (MDD). Despite decades of research, the precise aetiological relationship between CFS and MDD remains poorly understood. This has resulted in the development of a number of interesting and polarised hypotheses regarding the aetiological nature of CFS. Recent scientific advances have however begun to unravel a number of interesting inflammatory and immunological explanations that suggest CFS and MDD are distinct yet interrelated conditions. The possibility that the overlap between CFS and MDD might be explained in terms of shared oxidative and nitrosative (IO&NS) pathways is an area of intense research interest and is reviewed in detail in this article. The overlap between CFS and MDD is further differentiated by variations in HPA axis activity between the two disorders. Important immunological differences between MDD and CFS are also reviewed with particular emphasis on antiviral RNase L pathways in CFS. In addition to the presence of neuropsychiatric complaints, CFS is also associated with neuropsychological symptoms such as impaired attention, memory and reaction time. The key neuropsychological problems reported by CFS patients are also included in the review in an effort to understand the significance of cognitive impairment in CFS.

A narrative review on the similarities and dissimilarities between myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and sickness behavior

It is of importance whether myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a variant of sickness behavior. The latter is induced by acute infections/injury being principally mediated through proinflammatory cytokines. Sickness is a beneficial behavioral response that serves to enhance recovery, conserves energy and plays a role in the resolution of inflammation. There are behavioral/symptomatic similarities (for example, fatigue, malaise, hyperalgesia) and dissimilarities (gastrointestinal symptoms, anorexia and weight loss) between sickness and ME/CFS. While sickness is an adaptive response induced by proinflammatory cytokines, ME/CFS is a chronic, disabling disorder, where the pathophysiology is related to activation of immunoinflammatory and oxidative pathways and autoimmune responses. While sickness behavior is a state of energy conservation, which plays a role in combating pathogens, ME/CFS is a chronic disease underpinned by a state of energy depletion. While sickness is an acute response to infection/injury, the trigger factors in ME/CFS are less well defined and encompass acute and chronic infections, as well as inflammatory or autoimmune diseases. It is concluded that sickness behavior and ME/CFS are two different conditions.

Attention-deficit hyperactivity disorder in chronic fatigue syndrome patients

Psychopathological disorders are frequent in chronic fatigue syndrome patients. The present study examines the presence of attention-deficit hyperactivity disorder (ADHD) in a sample of adult chronic fatigue syndrome (CFS) patients, and evaluates its clinical consequences in this population. CFS patients were assessed for childhood and adult ADHD by clinical interview and ADHD-specific scales. Psychopathological comorbidities were evaluated by clinical examination and questionnaires. Forty-seven of 158 CSF patients (29.7%) were diagnosed of childhood ADHD and in 33 (20.9%), the condition persisted into adulthood. CFS patients with adult ADHD had an earlier CSF onset, more severe anxiety and depression symptoms, and a higher risk of suicide than CFS patients without ADHD. Using lineal regression analysis, we found that depressive symptoms and ADHD severity were significant predictors of fatigue intensity. Consequently, ADHD may be common in CFS patients, and is associated with a more severe psychopathologic clinical profile.

Linking disease symptoms and subtypes with personalized systems-based phenotypes: a proof of concept study

A dynamic systems model was used to generate parameters describing a phenotype of Hypothalamic-Pituitary-Adrenal (HPA) behavior in a sample of 36 patients with chronic fatigue syndrome (CFS) and/or fibromyalgia (FM) and 36 case-matched healthy controls. Altered neuroendocrine function, particularly in relation to somatic symptoms and poor sleep quality, may contribute to the pathophysiology of these disorders. Blood plasma was assayed for cortisol and ACTH every 10 min for 24h. The dynamic model was specified with an ordinary differential equation using three parameters: (1) ACTH-adrenal signaling, (2) inhibitory feedback, and (3) non-ACTH influences. The model was "personalized" by estimating an individualized set of parameters from each participant's data. Day and nighttime parameters were assessed separately. Two nocturnal parameters (ACTH-adrenal signaling and inhibitory feedback) significantly differentiated the two patient subgroups ("fatigue-predominant" patients with CFS only versus "pain-predominant" patients with FM and comorbid chronic fatigue) from controls (all p's<.05), whereas daytime parameters and diurnal/nocturnal slopes did not. The same nocturnal parameters were significantly associated with somatic symptoms among patients (p's<.05). There was a significantly different pattern of association between nocturnal non-ACTH influences and sleep quality among patients versus controls (p<.05). Although speculative, the finding that patient somatic symptoms decreased when more cortisol was produced per unit ACTH, is consistent with cortisol's anti-inflammatory and sleep-modulatory effects. Patients' HPA systems may compensate by promoting more rapid or sustained cortisol production. Mapping "behavioral phenotypes" of stress-arousal systems onto symptom clusters may help disentangle the pathophysiology of complex disorders with frequent comorbidity.

Psychological and physiological effects of caring for patients with treatment-resistant depression

BACKGROUND

Carers of patients with psychiatric disorders show high levels of anxiety and depression, possibly mediated through disruption of the hypothalamo-pituitary-adrenal (HPA) axis. Among carers of patients with treatment-resistant depression (TRD), we set out to determine the psychological and physiological (HPA axis) consequences of caring, and the association of these consequences with long-term outcome in patients.

METHOD

Thirty-five informal carers of patients with severe TRD requiring in-patient treatment were recruited and compared with 23 controls. HPA-axis activity was assessed by measuring post-awaking salivary cortisol. The Involvement Evaluation Questionnaire (IEQ) and the General Health Questionnaire-12 (GHQ-12) were administered to measure carer burden and psychiatric caseness respectively. Independent t tests were used to compare differences between carers and controls and a linear regression model was used to determine the association of post-awakening cortisol with carer status while controlling for confounding variables. Data on long-term patient outcome (12 to 83 months), measured using the Hamilton Depression Rating Scale (HAMD), were also obtained and linear regression was used to determine the association between cortisol output in carers and remission status in patients.

RESULTS

Carers experienced high carer burden and high psychiatric caseness. Carers showed reduced cortisol output after awakening, calculated as the area under the curve with respect to ground (AUCg), which remained significant after controlling for potential confounders. In a linear regression model, non-remission in patients was associated with reduced cortisol output in carers.

CONCLUSIONS

Caring for patients with TRD is associated with adverse psychological and physiological changes suggesting hypocortisolism post-awakening. These changes are associated with poor patient outcome.

Shilajit attenuates behavioral symptoms of chronic fatigue syndrome by modulating the hypothalamic-pituitary-adrenal axis and mitochondrial bioenergetics in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Shilajit has been used as a rejuvenator for ages in Indian ancient traditional medicine and has been validated for a number of pharmacological activities.

AIM OF THE STUDY

The effect of processed shilajit which was standardized to dibenzo-α-pyrones (DBPs;0.43% w/w), DBP-chromoproteins (DCPs; 20.45% w/w) and fulvic acids (56.75% w/w) was evaluated in a rat model of chronic fatigue syndrome (CFS). The mitochondrial bioenergetics and the activity of hypothalamus-pituitary-adrenal (HPA) axis were evaluated for the plausible mechanism of action of shilajit.

MATERIALS AND METHODS

CFS was induced by forcing the rats to swim for 15mins for 21 consecutive days. The rats were treated with shilajit (25, 50 and 100mg/kg) for 21 days before exposure to stress procedure. The behavioral consequence of CFS was measured in terms of immobility and the climbing period. The post-CFS anxiety level was assessed by elevated plus maze (EPM) test. Plasma corticosterone and adrenal gland weight were estimated as indices of HPA axis activity. Analysis of mitochondrial complex chain enzymes (Complex I, II, IV and V) and mitochondrial membrane potential (MMP) in prefrontal cortex (PFC) were performed to evaluate the mitochondrial bioenergetics and integrity respectively.

RESULTS

Shilajit reversed the CFS-induced increase in immobility period and decrease in climbing behavior as well as attenuated anxiety in the EPM test. Shilajit reversed CFS-induced decrease in plasma corticosterone level and loss of adrenal gland weight indicating modulation of HPA axis. Shilajit prevented CFS-induced mitochondrial dysfunction by stabilizing the complex enzyme activities and the loss of MMP. Shilajit reversed CFS-induced mitochondrial oxidative stress in terms of NO concentration and, LPO, SOD and catalase activities.

CONCLUSION

The results indicate that shilajit mitigates the effects of CFS in this model possibly through the modulation of HPA axis and preservation of mitochondrial function and integrity. The reversal of CFS-induced behavioral symptoms and mitochondrial bioenergetics by shilajit indicates mitochondria as a potential target for treatment of CFS.

Hypothalamic-pituitary-adrenal axis dysfunction in chronic fatigue syndrome

The weight of current evidence supports the presence of the following factors related to hypothalamic-pituitary-adrenal (HPA) axis dysfunction in patients with chronic fatigue syndrome (CFS): mild hypocortisolism; attenuated diurnal variation of cortisol; enhanced negative feedback to the HPA axis; and blunted HPA axis responsiveness. Furthermore, HPA axis changes seem clinically relevant, as they are associated with worse symptoms and/or disability and with poorer outcomes to standard treatments for CFS. Regarding etiology, women with CFS are more likely to have reduced cortisol levels. Studies published in the past 8 years provide further support for a multifactorial model in which several factors interact to moderate HPA axis changes. In particular, low activity levels, depression and early-life stress appear to reduce cortisol levels, whereas the use of psychotropic medication can increase cortisol. Addressing these factors-for example, with cognitive behavioral therapy-can increase cortisol levels and is probably the first-line approach for correcting HPA axis dysfunction at present, as steroid replacement is not recommended. Given what is now a fairly consistent pattern of findings for the type of HPA axis changes found in CFS, we recommend that future work focuses on improving our understanding of the cause and relevance of these observed changes.

Corticosterone pretreatment suppresses stress-induced hypothalamic-pituitary-adrenal axis activity via multiple actions that vary with time, site of action, and de novo protein synthesis

Glucocorticoid regulation of the hypothalamic-pituitary-adrenal (HPA) axis is believed to depend on multiple actions operative within discrete time domains. However, the underlying cellular and molecular mechanisms for those glucocorticoid actions remain undetermined. Moreover, there is absence of in vivo studies examining whether there are multiple glucocorticoid effects on HPA axis-related function within an intermediate feedback time frame (1-3  h after glucocorticoid elevation), and whether those effects depend on de novo protein synthesis. We examined in rats the effects of protein synthesis inhibition on HPA axis response to restraint (15 min) after 1 and 3  h phasic corticosterone (CORT) pretreatment. We measured HPA axis hormones (ACTH and CORT) and gene expression in the paraventricular nucleus (c-fos and crh genes), as well as gene expression in the anterior and intermediate pituitaries (c-fos and pomc genes). Both CORT pretreatment intervals produced inhibition of stress-induced ACTH secretion, but no inhibition was observed in the presence of protein synthesis inhibition. CORT pretreatment produced inhibitory effects on stress-induced gene expression that varied for each gene depending on the anatomical site, pretreatment time, and protein synthesis dependency. Taken together, the ACTH and gene expression patterns support the presence of multiple independent glucocorticoid actions initiated during the intermediate glucocorticoid negative feedback phase. Moreover, we conclude that those effects are exerted predominantly on the intrinsic anatomical elements of the HPA axis, and some of those effects depend on CORT induction of the expression of one or more regulatory gene products.

Interface between hypothalamic-pituitary-adrenal axis and brain-derived neurotrophic factor in depression

Although the pathophysiology of depressive disorder remains elusive, two hypothetical frameworks seem to be promising: the involvement of hypothalamic pituitary-adrenal (HPA) axis abnormalities and brain-derived neurotrophic factor (BDNF) in the pathogenesis and in the mechanism of action of antidepressant treatments. In this review, we focused on research based on these two frameworks in relation to depression and related conditions and tried to formulate an integrated theory of the disorder. Hormonal challenge tests, such as the dexamethasone/corticotropin-releasing hormone test, have revealed elevated HPA activity (hypercortisolism) in at least a portion of patients with depression, although growing evidence has suggested that abnormally low HPA axis (hypocortisolism) has also been implicated in a variety of stress-related conditions. Several lines of evidence from postmortem studies, animal studies, blood levels, and genetic studies have suggested that BDNF is involved in the pathogenesis of depression and in the mechanism of action of biological treatments for depression. Considerable evidence has suggested that stress reduces the expression of BDNF and that antidepressant treatments increase it. Moreover, the glucocorticoid receptor interacts with the specific receptor of BDNF, TrkB, and excessive glucocorticoid interferes with BDNF signaling. Altered BDNF function is involved in the structural changes and possibly impaired neurogenesis in the brain of depressed patients. Based on these findings, an integrated schema of the pathological and recovery processes of depression is illustrated.

Neuroendocrine and immune contributors to fatigue

Central fatigue, a persistent and subjective sense of tiredness, generally correlates poorly with traditional markers of disease. It is frequently associated with psychosocial factors, such as depression, sleep disorder, anxiety, and coping style, which suggest that dysregulation of the body's stress systems may serve as an underlying mechanism in the maintenance of chronic fatigue (CF). This article addresses the endocrine, neural, and immune factors that contribute to fatigue and describes research regarding the role of these factors in chronic fatigue syndrome as a model for addressing the biology of CF. In general, hypoactivity of the hypothalamic-pituitary-adrenal axis, autonomic nervous system alterations characterized by sympathetic overactivity and low vagal tone, as well as immune abnormalities, may contribute to the expression of CF. Noninvasive methods for evaluating endocrine, neural, and immune function are also discussed. Simultaneous evaluation of neuroendocrine and immune systems with noninvasive techniques will help elucidate the underlying interactions of these systems, their role in disease susceptibility, and progression of stress-related disorders.

Depression and anxiety correlate differently with salivary free cortisol in the morning in patients with functional somatic syndrome

Patients presenting with functional somatic syndrome (FSS) are common, and the symptoms are persistent and difficult to treat for doctors and costly for society. The aim of this study was to clarify the common pathophysiology of FSS, especially the relationship between hypothalamic-pituitary-adrenal (HPA) axis function and psychological characteristics of patients with FSS. The subjects were 45 patients with FSS and 29 healthy controls. Salivary free cortisol was measured in the morning, and psychological tests examining depression, anxiety and quality of life (QOL) were performed on the same day. In patients with FSS, depressive scores showed a significant negative correlation with salivary free cortisol in the morning, although in healthy controls, cortisol showed a significant positive correlation with depressive scores. In addition, the correlation between other psychological test scores and cortisol secretion in patients with FSS contrasted with that of controls. The relationship between cortisol and depression, anxiety or QOL, suggests that the HPA axis of patients with FSS is dysfunctional and does not function properly when patients with FSS are under stress. This dysfunction may explain the pathology of medically unexplained persistent symptoms of patients with FSS.

HPA axis reactivity in chronic pelvic pain: association with depression

OBJECTIVES

Chronic pelvic pain (CPP) is a frequent gynecological complaint. The pathophysiology of CPP is not fully understood. The aim of this study was to determine whether the presence of depressive symptoms is associated with hypothalamic-pituitary-adrenal (HPA) axis dysfunction in CPP.

METHODS

We measured neuroendocrine responses to a standardized social stress test and to a standard adrenocorticotropin (ACTH)(1-24) stimulation test in 18 patients with CPP, stratified based on the presence of high versus low self-reported depressive symptoms, compared with 24 controls.

RESULTS

Women with CPP and low depression exhibited enhanced ACTH responses to psychosocial stress compared with women with CPP and high depression, whereas there were no differences in cortisol responses. In the ACTH(1-24) stimulation test, CPP patients with high depression demonstrated enhanced cortisol responses.

CONCLUSION

These results suggest a relationship between self-reported depression and reactivity of the HPA axis in patients with CPP.

Moderate exercise increases expression for sensory, adrenergic, and immune genes in chronic fatigue syndrome patients but not in normal subjects

Chronic fatigue syndrome (CFS) is characterized by debilitating fatigue, often accompanied by widespread muscle pain that meets criteria for fibromyalgia syndrome (FMS). Symptoms become markedly worse after exercise. Previous studies implicated dysregulation of the sympathetic nervous system (SNS), and immune system (IS) in CFS and FMS. We recently demonstrated that acid sensing ion channel (probably ASIC3), purinergic type 2X receptors (probably P2X4 and P2X5) and the transient receptor potential vanilloid type 1 (TRPV1) are molecular receptors in mouse sensory neurons detecting metabolites that cause acute muscle pain and possibly muscle fatigue. These molecular receptors are found on human leukocytes along with SNS and IS genes. Real-time, quantitative PCR showed that 19 CFS patients had lower expression of beta-2 adrenergic receptors but otherwise did not differ from 16 control subjects before exercise. After a sustained moderate exercise test, CFS patients showed greater increases than control subjects in gene expression for metabolite detecting receptors ASIC3, P2X4, and P2X5, for SNS receptors alpha-2A, beta-1, beta-2, and COMT and IS genes for IL10 and TLR4 lasting from 0.5 to 48 hours (P < .05). These increases were also seen in the CFS subgroup with comorbid FMS and were highly correlated with symptoms of physical fatigue, mental fatigue, and pain. These new findings suggest dysregulation of metabolite detecting receptors as well as SNS and IS in CFS and CFS-FMS.

PERSPECTIVE

Muscle fatigue and pain are major symptoms of CFS. After moderate exercise, CFS and CFS-FMS patients show enhanced gene expression for receptors detecting muscle metabolites and for SNS and IS, which correlate with these symptoms. These findings suggest possible new causes, points for intervention, and objective biomarkers for these disorders.

Impaired immune function in Gulf War Illness

Background

Gulf War Illness (GWI) remains a serious health consequence for at least 11,000 veterans of the first Gulf War in the early 1990s. Our understanding of the health consequences that resulted remains inadequate, and this is of great concern with another deployment to the same theater of operations occurring now. Chronic immune cell dysfunction and activation have been demonstrated in patients with GWI, although the literature is not uniform. We exposed GWI patients and matched controls to an exercise challenge to explore differences in immune cell function measured by classic immune assays and gene expression profiling.

Methods

This pilot study enrolled 9 GWI cases identified from the Department of Veterans Affairs GWI registry, and 11 sedentary control veterans who had not been deployed to the Persian Gulf and were matched to cases by sex, body mass index (BMI) and age. We measured peripheral blood cell numbers, NK cytotoxicity, cytokines and expression levels of 20,000 genes immediately before, immediately after and 4 hours following a standard bicycle ergometer exercise challenge.

Results

A repeated-measures analysis of variance revealed statistically significant differences for three NK cell subsets and NK cytotoxicity between cases and controls (p < 0.05). Linear regression analysis correlating NK cell numbers to the gene expression profiles showed high correlation of genes associated with NK cell function, serving as a biologic validation of both the in vitro assays and the microarray platform. Intracellular perforin levels in NK and CD8 T-cells trended lower and showed a flatter profile in GWI cases than controls, as did the expression levels of the perforin gene PRF1. Genes distinguishing cases from controls were associated with the glucocorticoid signaling pathway.

Conclusion

GWI patients demonstrated impaired immune function as demonstrated by decreased NK cytotoxicity and altered gene expression associated with NK cell function. Pro-inflammatory cytokines, T-cell ratios, and dysregulated mediators of the stress response (including salivary cortisol) were also altered in GWI cases compared to control subjects. An interesting and potentially important observation was that the exercise challenge augments these differences, with the most significant effects observed immediately after the stressor, possibly implicating some block in the NK and CD8 T-cells ability to respond to "stress-mediated activation". This has positive implications for the development of laboratory diagnostic tests for this syndrome and provides a paradigm for exploration of the immuno-physiological mechanisms that are operating in GWI, and similar complex syndromes. Our results do not necessarily elucidate the cause of GWI, but they do reveal a role for immune cell dysfunction in sustaining illness.

Does hypothalamic-pituitary-adrenal axis hypofunction in chronic fatigue syndrome reflect a 'crash' in the stress system?

The etiopathogenesis of chronic fatigue syndrome (CFS) remains poorly understood. Although neuroendocrine disturbances - and hypothalamic-pituitary-adrenal (HPA) axis hypofunction in particular - have been found in a large proportion of CFS patients, it is not clear whether these disturbances are cause or consequence of the illness. After a review of the available evidence we hypothesize that that HPA axis hypofunction in CFS, conceptualized within a system-biological perspective, primarily reflects a fundamental and persistent dysregulation of the neurobiological stress system. As a result, a disturbed balance between glucocorticoid and inflammatory signaling pathways may give rise to a pathological cytokine-induced sickness response that may be the final common pathway underlying central CFS symptoms, i.e. effort/stress intolerance and pain hypersensitivity. This comprehensive hypothesis on HPA axis hypofunction in CFS may stimulate diagnostic refinement of the illness, inform treatment approaches and suggest directions for future research, particularly focusing on the neuroendocrine-immune interface and possible links between CFS, early and recent life stress, and depression.

Model-based therapeutic correction of hypothalamic-pituitary-adrenal axis dysfunction

The hypothalamic-pituitary-adrenal (HPA) axis is a major system maintaining body homeostasis by regulating the neuroendocrine and sympathetic nervous systems as well modulating immune function. Recent work has shown that the complex dynamics of this system accommodate several stable steady states, one of which corresponds to the hypocortisol state observed in patients with chronic fatigue syndrome (CFS). At present these dynamics are not formally considered in the development of treatment strategies. Here we use model-based predictive control (MPC) methodology to estimate robust treatment courses for displacing the HPA axis from an abnormal hypocortisol steady state back to a healthy cortisol level. This approach was applied to a recent model of HPA axis dynamics incorporating glucocorticoid receptor kinetics. A candidate treatment that displays robust properties in the face of significant biological variability and measurement uncertainty requires that cortisol be further suppressed for a short period until adrenocorticotropic hormone levels exceed 30% of baseline. Treatment may then be discontinued, and the HPA axis will naturally progress to a stable attractor defined by normal hormone levels. Suppression of biologically available cortisol may be achieved through the use of binding proteins such as CBG and certain metabolizing enzymes, thus offering possible avenues for deployment in a clinical setting. Treatment strategies can therefore be designed that maximally exploit system dynamics to provide a robust response to treatment and ensure a positive outcome over a wide range of conditions. Perhaps most importantly, a treatment course involving further reduction in cortisol, even transient, is quite counterintuitive and challenges the conventional strategy of supplementing cortisol levels, an approach based on steady-state reasoning.

Glucocorticoid receptor mediated negative feedback in chronic fatigue syndrome using the low dose (0.5 mg) dexamethasone suppression test

BACKGROUND

Chronic fatigue syndrome (CFS) is associated with hypocortisolism, but it is not yet clear the extent to which enhanced negative feedback may underlie this finding.

METHODS

We undertook a low-dose dexamethasone (0.5 mg) suppression test in 18 CFS patients and 20 matched, healthy controls. We measured salivary cortisol levels at 0800 h, 1200 h, 1600 h and 2000 h before and after the administration of 0.5 mg of dexamethasone.

RESULTS

Basal cortisol output was raised in this group of CFS patients compared to controls. Overall, the percentage suppression following dexamethasone administration was no different between CFS (mean+/-sem: 80.4+/-4.4%) and controls (76.2+/-4.9 %). However, the sub-group of patients with CFS and comorbid depression (n=9) showed a significant hypersuppression of salivary cortisol in response to dexamethasone (89.0+/-1.9%; p<0.05 v controls).

LIMITATIONS

The sub-group analysis was on small numbers and should be considered preliminary. Dexamethasone probes only glucocorticoid medicated negative feedback but does not probe mineralocorticoid feedback, the other main physiological feedback mechanism.

CONCLUSION

We found partial support for the hypothesis of enhanced negative feedback in CFS but only in patients with comorbid depression and also in the context of a sample of patients with elevated basal cortisol levels, which is an atypical finding in the literature.

Treatment of chronic fatigue syndrome: findings, principles and strategies

Chronic fatigue syndrome (CFS) is a debilitating condition characterized by serious medically unexplained mental and physical fatigue. The high prevalence and both direct and indirect health costs of CFS patients represent a huge problem for contemporary health care. Moreover, the prognosis of CFS, even when treated, is often poor. In this paper, we first critically review current evidence based treatments of CFS. Second, we discuss the growing insights into the etiopathogenesis of CFS, and the need to translate and integrate these insights into future treatments. In particular, we formulate a pragmatic and empirically testable treatment approach, tailored to the individual needs of patients, which aims at restoring the mental and physical equilibrium of CFS patients by trying to bring about sustained life style changes.

Chronic fatigue syndrome and the central nervous system

An increasing amount of neuroimaging evidence supports the hypothesis that chronic fatigue syndrome patients have structural or functional abnormalities within the brain. Moreover, some neurotrophic factors, neurotransmitters and cytokines have also been evaluated in order to elucidate the mechanism of abnormal neuropsychic findings in chronic fatigue syndrome. In this review, we suggest that the focal point of chronic fatigue syndrome research should be transferred to the central nervous system.

Reference intervals of urinary steroid metabolites using gas chromatography-mass spectrometry in Chinese adults

BACKGROUND

Urinary steroid profiling by GC or GC-MS are established clinical tools to complement other biochemical tests in the diagnosis and investigation of a wide range of adrenocortical disorders, but normative data on adults using the more specific GC-MS are lacking. Our objective was to set up the reference intervals of commonly detected urinary steroid metabolites as well as marker metabolites seen in disease states.

METHOD

Apparently healthy adult Chinese males and females were recruited by completing health questionnaires. A 24-h urine specimen was collected from all the participants for urinary steroid profiling by GC-MS in cyclic scan mode. The analyzer was calibrated by using authentic steroid standards. Statistical methods recommended by the National Committee for Clinical Laboratory Standards were followed for setting up the reference intervals of various steroid metabolites. After outliers were excluded, the data were tested for the necessity to partition into sex-, menopausal status- and age-specific reference intervals.

RESULTS

83 males and 89 females were recruited for the study. Necessity to partition into sex-specific reference intervals was demonstrated for almost all steroid metabolites. Menopausal status and age also had a significant impact on steroid metabolite excretion, making separate reference intervals necessary.

CONCLUSIONS

We have set up the normative data on the levels of urinary steroid metabolite excretion in Chinese adults for future reference in patient management and research in steroid metabolism.

Combined dexamethasone/corticotropin-releasing factor test in chronic fatigue syndrome

BACKGROUND

Studies of hypothalamic-pituitary-adrenal (HPA) axis function in chronic fatigue syndrome (CFS) point to hypofunction, although there are negative reports. Suggested mechanisms include a reduced hypothalamic or supra-hypothalamic stimulus to the HPA axis and enhanced sensitivity to the negative feedback of glucocorticoids. The aim of the current study was to investigate HPA axis function in CFS with the dexamethasone/corticotropin-releasing factor (Dex/CRF) test, in analogy with research in affective disorders.

METHOD

Thirty-four well-characterized female CFS patients and 25 healthy control subjects participated in the low-dose Dex/CRF test. Current major depressive episode was an exclusion criterion. History of early-life stress (ELS) was assessed with the Structured Trauma Interview.

RESULTS

Salivary cortisol responses after 0.5 mg Dex were lower in CFS patients than in controls (before 100 microg CRF, p=0.038; after 100 microg CRF, p=0.015). A secondary analysis revealed an influence of early-life stress and of oestrogen intake. After removal of the 10 participants who were taking an oral oestrogen, patients without a history of ELS showed lower cortisol responses than patients with ELS and controls (before CRF, p=0.005; after CRF, p=0.008).

CONCLUSIONS

CFS is globally associated with reduced cortisol responses in the combined low-dose Dex/CRF test, but this effect is only clearly present in CFS patients without a history of ELS. This study provides further support for an enhanced glucocorticoid negative feedback and/or a reduced central HPA axis drive in CFS. Furthermore, it demonstrates that ELS is an important variable to consider in CFS research.

Chronic fatigue syndrome: inflammation, immune function, and neuroendocrine interactions

Investigations into the underlying cause of chronic fatigue syndrome have advanced the field considerably in the past year. Gene microarray data have led to a better understanding of pathogenesis. Recent research has evaluated genetic signatures, described biologic subgroups, and suggested potential targeted treatments. Acute viral infection studies found that initial infection severity was the single best predictor of persistent fatigue. Genomic studies showed that persistent cases express Epstein Barr virus-specific genes and demonstrate abnormalities of mitochondrial function. Studies of immune dysfunction extended observations of natural killer cytotoxic cell dysfunction of the cytotoxic T cell through quantitative evaluation of intracellular perforins and granzymes. Other research has focused on a subgroup of patients with reactivated viral infection. These advances should result in targeted therapies that impact immune function, hypothalamic-pituitary-adrenal axis regulation, and persistent viral reactivation.

Rehabilitation of decreased motor performance in patients with chronic fatigue syndrome: should we treat low effort capacity or reduced effort tolerance?

Aim: The aetiology, pathophysiology, diagnostic delineation and treatment of chronic fatigue syndrome (CFS) remain a matter of debate. Here some aspects of the debate are elucidated, with a particular focus on the patients' decreased motor performance.

Hypothesis: The pathophysiological basis of decreased motor performance in CFS may, theoretically, involve three components: (1) a peripheral energetic deficit (impaired oxidative metabolism and/or physical deconditioning); (2) a central perceptual disturbance (higher effort sense or increased `interoception'); and (3) a fundamental failure of the neurobiological stress system, leading to an abnormal `sickness response'. It is proposed that the first two components may lead to low effort capacity, while the third component may lead to reduced effort tolerance. Although there is evidence for low effort capacity influencing symptoms and functional limitations in CFS, it is assumed that reduced effort tolerance might be the primary disturbance in CFS.

Diagnostic implications: Distinguishing low effort capacity and reduced effort tolerance may contribute to a refinement of current diagnostic criteria of CFS and the identification of subgroups.

Therapeutic implications: The above-mentioned distinction may make it possible to formulate a rationale for an effective implementation and adequate outcome evaluation of rehabilitation strategies in CFS.

Research implications: This new heuristic framework may inform future research aimed at disentangling the complex determination of impaired motor performance in CFS, as well as studies aimed at customizing treatment to different subtypes of patients.