The role of depression in pain, psychophysiological syndromes and medically unexplained symptoms associated with chronic fatigue syndrome

BACKGROUND: The association between depression and pain, function, medically unexplained symptoms and psychophysiological syndromes such as irritable bowel syndrome has not been explored before in chronic fatigue syndrome. METHODS: Cross-sectional controlled study of the current prevalence of psychophysiological syndromes, pain, function and lifetime prevalence of medically unexplained symptoms in 77 out-patients with chronic fatigue syndrome (CFS) without DSM-III-R depression, 42 CFS out-patients with DSM-III-R depression and 26 out-patient with primary DSM-III-R depression. RESULTS: Both CFS groups differed significantly from the primary depression group but not each other in the prevalence of tension headaches (P < 0.001), reporting of widespread bodily pain (P < 0.001) and the number of lifetime medically unexplained symptoms (P < 0.001). The three groups did not significantly differ in the prevalence of irritable bowel syndrome or fibromyalgia. CFS patients with depression were more impaired in social function than other CFS patients. CONCLUSION: Depression is not associated with the reporting of pain, psychophysiological syndromes and medically unexplained symptoms in CFS patients. Depression is associated with decreased social function in CFS patients. LIMITATIONS: Study depended on recall of symptoms, not confirmed by medical records and current investigations. Patients with depression were taking antidepressants. CLINICAL RELEVANCE: Treating depression in chronic fatigue syndrome is unlikely to diminish reporting of pain and medically unexplained symptoms but may improve social function.     

Illness behaviors in patients with unexplained chronic fatigue are associated with significant other responses

Chronic fatigue syndrome (CFS) and unexplained chronic fatigue (CF) are characterized by compromised functional status and physical disability. Prior research on chronic pain has suggested that social factors may contribute to disability. This study examined the relationship between significant other responses and patient outcomes in patients with unexplained CF. Questionnaire data were collected from 117 patients on physical function, fatigue, pain, illness behaviors and responses of significant others to them, and depression. Ninety-four SOs reported their perceptions of patient illness behavior and their responses. Thirty-seven of these dyads also completed a series of household activities while being videotaped. Dyadic interactions were coded and analyzed. Both reported and observed solicitous responses by the significant other were associated with reported and observed patient illness behavior. Negative responses to patient illness behavior by significant others were associated with higher levels of patient depressive symptoms. The findings provide support for the role of operant behavioral factors in the context of chronic fatigue. They also suggest that further research on the relationship between dysfunction and significant other responses in patients with CFS or CF appears warranted and may have implications for treatment development.     

Adrenocortical activity in at-risk and normally developing adolescents: individual differences in salivary cortisol basal levels, diurnal variation, and responses to social challenges

The purpose of this study was to examine adrenocortical activity (basal, diurnal variation, and responses to social stressors) in adolescents at risk for psychopathology. Salivary cortisol levels were examined in normally developing and at-risk youth with internalizing and externalizing symptoms ranging from subclinical to clinical levels. Adolescents showed expected patterns of diurnal variation, with high early morning cortisol levels and a pattern of decline throughout the day. Females showed higher midday and late afternoon levels than males, and these patterns interacted with risk status. Internalizing problems sometimes were associated with gradual rather than steep declines in basal cortisol production. Both immediate and delayed cortisol reactivity to a social performance stressor were associated with internalizing symptoms. There was no evidence of relations between externalizing problems and underarousal of the hypothalamic-pituitary-adrenal (HPA) system. These and other results suggest that gender is an important moderating factor linking psychopathology. development, and context with HPA axis functioning in adolescence.     

Hypothalamic-pituitary-adrenal axis reactivity in chronic fatigue syndrome and health under psychological,physiological, and pharmacological stimulation

OBJECTIVES: Subtle alterations of the hypothalamic-pituitary-adrenal (HPA) axis in chronic fatigue syndrome (CFS) have been proposed as a shared pathway linking numerous etiological and perpetuating processes with symptoms and observed physiological abnormalities. Because the HPA axis is involved in the adaptive responses to stress and CFS patients experience a worsening of symptoms after physical and psychological stress, we tested HPA axis functioning with three centrally acting stress tests. METHODS: We used two procedures mimicking real-life stressors and compared them with a standardized pharmacological neuroendocrine challenge test. CFS patients were compared with healthy control subjects regarding their cardiovascular and endocrine reactivity in a psychosocial stress test and a standardized exercise test, and their endocrine response in the insulin tolerance test (ITT). RESULTS: Controlling for possible confounding variables, we found significantly lower ACTH response levels in the psychosocial stress test and the exercise test, and significantly lower ACTH responses in the ITT, with no differences in plasma total cortisol responses. Also, salivary-free cortisol responses did not differ between the groups in the psychosocial stress test and the exercise test but were significantly higher for the CFS patients in the ITT. In all tests CFS patients had significantly reduced baseline ACTH levels. CONCLUSIONS: These results suggest that CFS patients are capable of mounting a sufficient cortisol response under different types of stress but that on a central level subtle dysregulations of the HPA axis exist.     

Post-traumatic stress disorder among patients with chronic pain and chronic fatigue

BACKGROUND: Fibromyalgia (FM), a chronic pain condition of unknown aetiology often develops following a traumatic event. FM has been associated with post-traumatic stress disorder (PTSD) and major depression disorder (MDD). METHOD: Patients seen in a referral clinic (N=571) were evaluated for FM and chronic fatigue syndrome (CFS) criteria. Patients completed questionnaires, and underwent a physical examination and a structured psychiatric evaluation. Critical components of the diagnostic criteria of FM (tender points and diffuse pain) and CFS (persistent debilitating fatigue and four of eight associated symptoms) were examined for their relationship with PTSD. RESULTS: The prevalence of lifetime PTSD was 20% and lifetime MDD was 42%. Patients who had both tender points and diffuse pain had a higher prevalence of PTSD (OR=3.4, 95% CI 2.0-5.8) compared with those who had neither of these FM criteria. Stratification by MDD and adjustment for sociodemographic factors and chronic fatigue revealed that the association of PTSD with FM criteria was confined to those with MDD. Patients with MDD who met both components of the FM criteria had a three-fold increase in the prevalence of PTSD (95% CI 1.5-7.1); conversely, FM patients without MDD showed no increase in PTSD (OR=1.3, 95% CI 0.5-3.2). The components of the CFS criteria were not significantly associated with PTSD. CONCLUSION: Optimal clinical care for patients with FM should include an assessment of trauma in general, and PTSD in particular. This study highlights the importance of considering co-morbid MDD as an effect modifier in analyses that explore PTSD in patients with FM.     

Sub-typing CFS patients on the basis of 'minor' symptoms

The diagnosis of chronic fatigue syndrome (CFS), an illness characterized by medically unexplained fatigue, depends on a clinical case definition representing one or more pathophysiological mechanisms. To prepare for studies of these mechanisms, this study sought to identify subtypes of CFS. In 161 women meeting 1994 criteria for CFS, principal components analysis of the 10 'minor' symptoms of CFS produced three factors interpreted to indicate musculoskeletal, infectious and neurological subtypes. Extreme scores on one or more of these factors characterized about 2/3 of the sample. Those characterized by the neurological factor were at increased risk of reduced scores on cognitive tests requiring attention, working memory, long-term memory or rapid performance. In addition, the neurological subtype was associated with reduced levels of function. Those characterized by the musculoskeletal factor were at increased risk for the diagnosis of fibromyalgia (chronic widespread pain and mechanical allodynia) and reduced physical function. Those characterized by the infectious factor were less likely to evidence co-occurring fibromyalgia, and showed lesser risk of functional impairment. The prevalence of disability was increased in those with the highest scores on any of the subtypes, as well as in those with high scores on multiple factors. Depression and anxiety, while frequently present, were not more prevalent in any particular subtype, and did not increase with the severity of specific symptom reports. Results suggest that subtypes of CFS may be identified from reports of the minor diagnostic symptoms, and that these subtypes demonstrate construct validity.     

Critical life events, infections, and symptoms during the year preceding chronic fatigue syndrome (CFS): an examination of CFS patients and subjects with a nonspecific life crisis.

OBJECTIVE: The purpose of this study was to describe the sequence of psychosocial events and infections preceding the onset of chronic fatigue syndrome (CFS). This information was related to the temporal development of crucial symptoms in relation to the onset of, namely, fatigue, sadness, irritability, pain, and feeling of fever. METHODS: A personal interview was conducted in 46 patients (mean age, 39.5 years; SD, 9 years) who fulfilled international CFS criteria. These patients were matched with regard to age and gender to 46 carefully matched control subjects. Twenty-three percent of the study subjects were men, and 77% were women. The patient at first identified the month that coincided with the onset of CFS. Similarly, each control subject was asked to identify a "very difficult period" within approximately the same period as the patient with whom the control subject was matched. A list of 14 different life events was perused. Participants were asked to identify for each month whether each of the listed events had occurred. Furthermore, they were asked to rate the importance of the events they had experienced. In addition, for each of the cardinal symptoms (fatigue, sadness, irritability, pain, and feeling of fever) and for each month, the subjects were asked to rate, on a visual analogue scale, the symptom intensity. Also, the number of infections was noted. RESULTS: A statistically significant group difference in fatigue intensity existed during the period 4 to 10 months before the onset of CFS. During the 3 months preceding the diagnosis for the CFS patients or the peak of the crisis for the control group, there was a dramatic rise in fatigue in both groups. The CFS group reached a much higher fatigue level, which leveled off somewhat during the first year of follow-up but still remained very high in comparison with the control group, which reached precrisis levels 4 months after the peak. Similar patterns were observed for fever and pain. With regard to sadness and irritability, no group difference was observed during the period preceding the crisis. In the patient group, the level stayed high throughout the whole first year of follow-up, whereas a slow return started in the control group; precrisis levels were reached after 1 year in this group. The prevalence ratio (CFS patients/control subjects) for negative events was around 1.0 for the periods 4 to 12 months preceding CFS but 1.9 during the quarter year preceding the onset. For infections, the prevalence ratio increased successively during the four quarters preceding CFS (from 1.4 to 2.3). CONCLUSIONS: According to the retrospective self-reports, there were differences between the groups in fatigue, pain, and feeling of fever during the months preceding the crisis. With regard to depressive and irritable feelings, no preillness differences were reported between the groups. There was a reported excess prevalence of both infections and negative life events during the quarter year preceding the onset of CFS or crisis. Potential sources of error are discussed. These findings must be replicated in longitudinal studies.     

Physical Activity, Emotional Stress, Sleep Disturbances, and Daily Fluctuations in Chronic Fatigue Symptomatology

The current study explored the relationships between physical and emotional stress and the symptomatology of chronic fatigue syndrome (CFS). Fifty-four CFS patients were studied using a longitudinal design. A self-report format was used to collect daily measures of major physical (sleep disturbance and physical activity) and emotional (subjective emotional stress level) stressors, as well as measures of levels of fatigue and secondary symptoms. The variables accounted for a moderate variance at the individual and occasion levels. Sleep disturbance and emotional stress were found to be positively associated with levels of fatigue and symptomatology, whereas physical activity was found to have a negative relationship with fatigue only. The severity of fatigue and symptoms were found to fluctuate daily in relation with the variables, indicating the complex nature of the associations.     

The relationship between prior psychiatric disorder and chronic fatigue: evidence from a national birth cohort study

BACKGROUND: Increased rates of psychiatric disorder have previously been reported in those diagnosed with chronic fatigue syndrome (CFS) or myalgic encephalomyelitis (ME), although the direction of causation in this relationship has not been established. We aimed to test the hypothesis that individuals with self-reported CFS/ME have increased levels of psychiatric disorder prior to the onset of their fatigue symptoms. METHOD: A total of 5,362 participants were prospectively followed with various measures of personality, psychiatric disorder and fatigue levels collected over the first 43 years of their life. CFS/ME was identified through self-report during a semi-structured interview at age 53 years. RESULTS: Thirty-four (1.1%) of the 3,035 subjects assessed at age 53 years reported a diagnosis of CFS/ME. CFS/ME was more common among females, but there was no association between CFS/ME and either social class, social mobility or educational level. Those with psychiatric illness between the ages of 15 and 36 years were more likely to report CFS/ME later in life with an odds ratio (OR, adjusted for sex) of 2.65 [95% confidence interval (CI) 1.26-5.57, p=0.01]. Increased levels of psychiatric illness, in particular depression and anxiety, were present prior to the occurrence of fatigue symptoms. There was a dose-response relationship between the severity of psychiatric symptoms and the likelihood of later CFS/ME. Personality factors were not associated with a self-reported diagnosis of CFS/ME. CONCLUSIONS: This temporal, dose-response relationship suggests that psychiatric disorders, or shared risk factors for psychiatric disorders, are likely to have an aetiological role in some cases of CFS/ME.     

A longitudinal study of the relationship between psychological distress and recurrence of upper respiratory tract infections in chronic fatigue syndrome

Objectives. Previous research has found that chronic fatigue syndrome (CFS) patients report increased susceptibility to upper respiratory tract illnesses (URTIs) when compared with healthy volunteers. This study aimed to replicate and extend this research by investigating the role of psychological distress (stress and negative mood) in the recurrence of URTIs in CFS patients as well as its role in the recurrence of CFS symptoms. Design. A 15‐week diary study. Methods. Measures of psychological stress, negative mood, recurrence of URTIs and symptoms were recorded each week for a 15‐week period. CFS patients (N = 21), who had been assessed and diagnosed according to the Oxford criteria, were recruited from the Cardiff Chronic Fatigue Clinic and compared with a matched group of healthy controls (N = 18). Frequency of occurrence of infectious illness and the relationship between psychological stress/negative mood and occurrence of illness were assessed. Results. CFS patients reported more URTIs than the controls. Stress scores (and negative mood) were significantly higher in the week prior to the occurrence of URTIs than in weeks when no subsequent illness occurred. High levels of psychological stress also preceded the severity of reported symptoms of fatigue in the CFS group. Conclusions. CFS patients reported more frequent URTIs than healthy controls and these recurrences were preceded by high levels of psychological stress. High levels of stress were also associated with greater subsequent fatigue. Possible explanations of these results are discussed.     

Sleep,neuroimmune and neuroendocrine functions in fibromyalgia and chronic fatigue syndrome

The justification for disordered chronobiology for fibromyalgia and chronic fatigue syndrome (CFS) is based on the following evidence: The studies on disordered sleep physiology and the symptoms of fibromyalgia and CFS; the experimental studies that draw a link between interleukin-1 (IL-1), immune-neuroendocrine-thermal systems and the sleep-wake cycle; studies and preliminary data of the inter-relationships of sleep-wakefulness, IL-1, and aspects of peripheral immune and neuroendocrine functions in healthy men and in women during differing phases of the menstrual cycle; and the observations of alterations in the immune-neuroendocrine functions of patients with fibromyalgia and CFS (Moldofsky, 1993b, d). Time series analyses of measures of the circadian pattern of the sleep-wake behavioural system, immune, neuroendocrine and temperature functions in patients with fibromyalgia and CFS should determine whether alterations of aspects of the neuro-immune-endocrine systems that accompany disordered sleep physiology result in nonrestorative sleep, pain, fatigue, cognitive and mood symptoms in patients with fibromyalgia and CFS.     

Increased ventricular lactate in chronic fatigue syndrome measured by 1H MRS imaging at 3.0 T. II: comparison with major depressive disorder

Chronic fatigue syndrome (CFS), a complex illness characterized by fatigue, impaired concentration, and musculoskeletal pain, is often misdiagnosed as a psychiatric illness due to the overlap of its symptoms with mood and anxiety disorders. Using proton magnetic resonance spectroscopic imaging (¹H MRSI), we previously measured levels of the major brain metabolites in CFS, in generalized anxiety disorder (GAD), and in healthy control subjects, and found significantly higher levels of ventricular cerebrospinal fluid (CSF) lactate in CFS compared to the other two groups. In the present study, we sought to assess the specificity of this observation for CFS by comparing ventricular lactate levels in a new cohort of 17 CFS subjects with those in 19 healthy volunteers and in 21 subjects with major depressive disorder (MDD), which, like GAD, is a neuropsychiatric disorder that has significant symptom overlap with CFS. Ventricular CSF lactate was significantly elevated in CFS compared to healthy volunteers, replicating the major result of our previous study. Ventricular lactate measures in MDD did not differ from those in either CFS or healthy volunteers. We found a significant correlation between ventricular CSF lactate and severity of mental fatigue that was specific to the CFS group. In an exploratory analysis, we did not find evidence for altered levels of the amino acid neurotransmitters, γ‐aminobutyric acid (GABA) and glutamate + glutamine (‘Glx’), in CFS compared to MDD or healthy controls. Future ¹H MRS studies with larger sample sizes and well‐characterized populations will be necessary to further clarify the sensitivity and specificity of neurometabolic abnormalities in CFS and MDD. Copyright © 2010 John Wiley & Sons, Ltd.     

Eosinophil cationic protein serum levels and allergy in chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is a syndrome of uncertain etiopathogenesis characterized by disabling fatigue associated with a variable number of somatic and/or neuropsychologic symptoms. In patients with CFS, several immunologic abnormalities can be detected, including a higher prevalence of allergy. The aim of this study was to determine whether CFS patients, well studied for their allergy profile, show signs of eosinophil activation, as detectable by the measurement in serum of eosinophil cationic protein (ECP) levels. In 35 consecutive CFS outpatients (diagnosis based on the Centers for Disease Control case definition), ECP was measured in serum by a competitive enzyme immunoassay (ECP-FEIA kit, Kabi Pharmacia Diagnostics, Uppsala, Sweden). Fourteen disease-free subjects with no history of CFS or allergy were selected as controls. ECP serum levels were significantly higher in CFS patients than in controls (18.0±11.3 μg/1 vs 7.3 ± 2.1 μg/1; P < 0.01). In the CFS population, the prevalence of RAST positivity to one or more allergens was 77%, while no control showed positive RAST. Twelve of the 14 CFS patients with increased ECP serum levels were RAST-positive. However, CFS RAST-positive patients had no significantly higher ECP serum levels than CFS RAST-negative patients (19.3 ± 12.4 μg/1 vs 13.6 ± 3.7 μg/1; P = 0.4). This is the first report of increased serum levels of ECP in CFS. On the basis of the available data, it is discussed whether eosinophil activation has a pathogenetic role in CFS or is linked to the frequently associated allergic condition, or, finally, whether a common immunologic background may exist for both atopy and CFS.     

Daily hassles reported by chronic fatigue syndrome and fibromyalgia patients in tertiary care: a controlled quantitative and qualitative study

BACKGROUND: This study aimed at providing insight in the frequency, emotional impact and nature of daily hassles, experienced by patients suffering from chronic fatigue syndrome (CFS) and/or fibromyalgia (FM), compared with patients with a chronic organic disease. METHODS: One hundred and seventy-seven CFS/FM patients, 26 multiple sclerosis (MS) and 26 rheumatoid arthritis (RA) patients were investigated within 2-6 months after diagnosis. All patients completed a self-report questionnaire assessing daily hassles and associated distress, a visual analogue scale assessing fatigue and pain and a depression and anxiety questionnaire. RESULTS: CFS/FM patients show a higher frequency of hassles, higher emotional impact and higher fatigue, pain, depression and anxiety levels compared with MS/RA patients. Three hassle themes dominate in the CFS/FM group: dissatisfaction with oneself, insecurity and a lack of social recognition. In contrast, hassles reported by MS/RA patients show a much larger diversity and are not focused on person-dependent problems. CONCLUSIONS: Patients recently diagnosed as suffering from CFS and/or FM are highly preoccupied and distressed by daily hassles that have a severe impact on their self-image, as well as their personal, social and professional functioning. An optimal therapeutic approach of CFS and FM should take account of this heavy psychosocial burden, which might refer to core themes of these patients' illness experience.     

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

BACKGROUND: Hyperactivity and hypoactivity of the HPA have been forwarded as of pathophysiological relevance in major depressive disorder and chronic fatigue syndrome (CFS), respectively. METHODS: This study examines cortisol levels in the two disorders, and also assesses levels of the adrenal androgens, dehydroepiandrosterone (DHEA) and its sulphate derivative (DHEA-S), and 17-alpha-hydroxyprogesterone; 15 subjects with CFS diagnosed according to CDC criteria, 15 subjects with DSM III-R major depression and 11 healthy subjects were compared. RESULTS: DHEA and DHEA-S levels were significantly lower in the CFS compared to the healthy group; DHEA-S levels, but not DHEA, were lower in the depressives; cortisol and 17-alpha-hydroxyprogesterone did not differ between the three groups. CONCLUSIONS: A potential role for DHEA, both therapeutically and as a diagnostic tool, in CFS, is suggested.     

Discriminating between chronic fatigue syndrome and depression: a cognitive analysis

BACKGROUND: Chronic fatigue syndrome (CFS) and depression share a number of common symptoms and the majority of CFS patients meet lifetime criteria for depression. While cognitive factors seem key to the maintenance of CFS and depression, little is known about how the cognitive characteristics differ in the two conditions. METHODS: Fifty-three CFS patients were compared with 20 depressed patients and 38 healthy controls on perceptions of their health, illness attributions, self-esteem, cognitive distortions of general and somatic events, symptoms of distress and coping. A 6 month follow-up was also conducted to determine the stability of these factors and to investigate whether CFS-related cognitions predict ongoing disability and fatigue in this disorder. RESULTS: Between-group analyses confirmed that the depressed group was distinguished by low self-esteem, the propensity to make cognitive distortions across all situations, and to attribute their illness to psychological factors. In contrast, the CFS patients were characterized by low ratings of their current health status, a strong illness identity, external attributions for their illness, and distortions in thinking that were specific to somatic experiences. They were also more likely than depressed patients to cope with their illness by limiting stress and activity levels. These CFS-related cognitions and behaviours were associated with disability and fatigue 6 months later. CONCLUSIONS: CFS and depression can be distinguished by unique cognitive styles characteristic of each condition. The documented cognitive profile of the CFS patients provides support for the current cognitive behavioural models of the illness.     

Fatigue rating scales: an empirical comparison

BACKGROUND: There has been limited research comparing the efficacy of different fatigue rating scales for use with individuals with chronic fatigue syndrome (CFS). This investigation explored relationships between two commonly-used fatigue rating scales in CFS research, the Fatigue Scale and the Fatigue Severity Scale. Theoretically, these scales have been described as measuring different aspects of the fatigue construct. The Fatigue Scale was developed as a measure of the severity of specific fatigue-related symptoms, while the Fatigue Severity Scale was designed to assess functional outcomes related to fatigue. METHODS: Associations of these scales with the eight definitional symptoms of CFS and with eight domains of functional disability were examined separately in: (1) an overall sample of individuals with a wide range of fatigue severity and symptomatology; (2) a subsample of individuals with CFS-like symptomatology, and, (3) a subsample of healthy controls. RESULTS: Findings revealed that both scales are appropriate and useful measures of fatigue-related symptomatology and disability within a general population of individuals with varying levels of fatigue. However, the Fatigue Severity Scale appears to represent a more accurate and comprehensive measure of fatigue-related severity, symptomatology, and functional disability for individuals with CFS-like symptomatology.     

Metacognitive factors in chronic fatigue syndrome

Chronic fatigue syndrome (CFS), which is characterized by fatigue and flu-like symptoms that are not alleviated by rest, is a poorly understood condition and an often controversial diagnosis. Earlier research has indicated that general metacognitions are associated with the severity of symptoms in patients with CFS. In the current study, we aimed to determine whether specific metacognitive factors are implicated in CFS. Using the metacognitive profiling interview template we investigated the following: (1) whether patients held positive or negative metacognitions about conceptual processes; (2) what their goals with respect to engaging in these processes were; and (3) what indicated that it was appropriate to stop. We also examined attention focus when experiencing CFS symptoms, and its advantages and disadvantages. Results showed that patients endorsed positive and negative metacognitions pertaining to conceptual processes. The goals of engaging in these processes were to identify the cause of, and devise strategies to cope with, symptoms. Patients were either unable to identify a stop signal for conceptual processing or identified an improvement in fatigue-related symptoms as representing the stop signal. Finally, patients reported that their attention focus when experiencing symptoms included distraction and monitoring of symptoms. Advantages to these strategies included symptom management, whereas disadvantages included an escalation of negative affect. The present findings provide preliminary evidence that specific metacognitive factors may be involved in CFS. Copyright ? 2011 John Wiley & Sons, Ltd. KEY PRACTITIONER MESSAGE: Metacognitive profiling that may aid assessment and conceptualisation of psychological distress in CFS.     

Symptom occurrence in persons with chronic fatigue syndrome.

This investigation compared differences in the occurrence of symptoms in participants with CFS, melancholic depression, and no fatigue (controls). The following Fukuda et al. [Ann. Intern. Med. 121 (1994) 953] criteria symptoms differentiated the CFS group from controls, but did not differentiate the melancholic depression group from controls: headaches, lymph node pain, sore throat, joint pain, and muscle pain. In addition, participants with CFS uniquely differed from controls in the occurrence of muscle weakness at multiple sites as well as in the occurrence of various cardiopulmonary, neurological, and other symptoms not currently included in the current case definition. Implications of these findings are discussed.     

Increased nuclear factor-κB and loss of p53 are key mechanisms in Myalgic Encephalomyelitis/chronic fatigue syndrome (ME/CFS)

Fukuda’s criteria are adequate to make a distinction between Myalgic Encephalomyelitis/chronic fatigue syndrome (ME/CFS) and chronic fatigue (CF), but ME/CFS patients should be subdivided into those with (termed ME) and without (termed CFS) post exertional malaise [Maes et al. 2012]. ME/CFS is considered to be a neuro-immune disease. ME/CFS is characterized by activated immuno-inflammatory pathways, including increased levels of pro-inflammatory cytokines, nuclear factor κB (NF-κB) and aberrations in mitochondrial functions, including lowered ATP. These processes may explain typical symptoms of ME/CFS, e.g. fatigue, malaise, hyperalgesia, and neurologic and autonomic symptoms. Here we hypothesize that increased NF-κB together with a loss of p53 are key phenomena in ME/CFS that further explain ME/CFS symptoms, such as fatigue and neurocognitive dysfunction, and explain ME symptoms, such as post-exertional malaise following mental and physical activities. Inactivation of p53 impairs aerobic mitochondrial functions and causes greater dependence on anaerobic glycolysis, elevates lactate levels, reduces mitochondrial density in skeletal muscle and reduces endurance during physical exercise. Lowered p53 and increased NF-κB are associated with elevated reactive oxygen species. Increased NF-κB induces the production of pro-inflammatory cytokines, which increase glycolysis and further compromise mitochondrial functions. All these factors together may contribute to mitochondrial exhaustion and indicate that the demand for extra ATP upon the commencement of increased activity cannot be met. In conditions of chronic inflammation and oxidative stress, high NF-κB and low p53 may conspire to promote neuron and glial cell survival at a price of severely compromised metabolic brain function. Future research should examine p53 signaling in ME/CFS.