Meta-analysis of natural killer cell cytotoxicity in myalgic encephalomyelitis/chronic fatigue syndrome.

Reduced natural killer (NK) cell cytotoxicity is the most consistent immune finding in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Meta-analysis of the published literature determined the effect size of the decrement in ME/CFS. Databases were screened for papers comparing NK cell cytotoxicity in ME/CFS and healthy controls. A total of 28 papers and 55 effector:target cell ratio (E:T) data points were collected. Cytotoxicity in ME/CFS was significantly reduced to about half of healthy control levels, with an overall Hedges' g of 0.96 (0.75-1.18). Heterogeneity was high but was explained by the range of E:T ratios, different methods, and potential outliers. The outcomes confirm reproducible NK cell dysfunction in ME/CFS and will guide studies using the NK cell model system for pathomechanistic investigations. Systematic review registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42024542140.

Chronic Fatigue Syndrome: Diagnosis, Treatment, and Future Direction.

Myalgic encephalomyelitis (ME), also known as chronic fatigue syndrome (CFS), is a complex, chronic condition marked by persistent, debilitating fatigue that is not alleviated by rest and often worsens with physical or mental exertion. Along with fatigue, patients experience various symptoms, including cognitive impairments, post-exertional malaise, muscle and joint pain, sleep disturbances, and immune system dysfunction. Diagnosing CFS/ME is challenging due to the absence of definitive biomarkers, the overlap of symptoms with other conditions, and the lack of standardized diagnostic criteria. This comprehensive literature review aims to contribute to the understanding of CFS/ME, including its diagnosis, pathophysiology, differential diagnosis, treatment, and future directions.

Comparison of cognitive behaviour therapy versus activity management, both delivered remotely, to treat paediatric chronic fatigue syndrome/myalgic encephalomyelitis: the UK FITNET-NHS RCT.

Design: Parallel-group randomised controlled trial. Methods: Adolescents aged 11-17 years, diagnosed with myalgic encephalomyelitis/chronic fatigue syndrome and with no local specialist treatment centre, were referred to a specialist service in South West England. Interventions: Fatigue In Teenagers on the interNET in the National Health Service is a web-based myalgic encephalomyelitis/chronic fatigue syndrome-focused cognitive-behavioural therapy programme for adolescents, supported by individualised written, asynchronous electronic consultations with a clinical psychologist/cognitive-behavioural therapy practitioner. The comparator was videocall-delivered activity management with a myalgic encephalomyelitis/chronic fatigue syndrome clinician. Both treatments were intended to last 6 months. Objectives: Estimate the effectiveness of Fatigue In Teenagers on the interNET in the National Health Service compared to Activity Management for paediatric myalgic encephalomyelitis/chronic fatigue syndrome. Estimate the effectiveness of Fatigue In Teenagers on the interNET in the National Health Service compared to Activity Management for those with mild/moderate comorbid mood disorders. From a National Health Service perspective, estimate the cost-effectiveness of Fatigue In Teenagers on the interNET in the National Health Service compared to Activity Management over a 12-month horizon. Primary Outcome: 36-item Short Form Health Survey Physical Function subscale at 6 months post randomisation. Randomisation: Web-based, using minimisation with a random component to balance allocated groups by age and gender. Blinding: While the investigators were blinded to group assignment, this was not possible for participants, parents/carers and therapists. Results: The treatment of 314 adolescents was randomly allocated, 155 to Fatigue In Teenagers on the interNET in the National Health Service. Mean age was 14 years old and 63% were female. Primary outcome: At 6 months, participants allocated to Fatigue In Teenagers on the interNET in the National Health Service were more likely to have improved physical function (mean 60.5, standard deviation 29.5, n = 127) compared to Activity Management (mean 50.3, standard deviation 26.5, n = 138). The mean difference was 8.2 (95% confidence interval 2.7 to 13.6, p = 0.003). The result was similar for participants meeting the National Institute for Health and Care Excellence 2021 diagnostic criteria. Secondary outcomes: Fatigue In Teenagers on the interNET in the National Health Service participants attended, on average, half a day more school per week at 6 months than those allocated Activity Management, and this difference was maintained at 12 months. There was no strong evidence that comorbid mood disorder impacted upon the relative effectiveness of the two interventions. Similar improvement was seen in the two groups for pain and the Clinical Global Impression scale, with a mixed picture for fatigue. Both groups continued to improve, and no clear difference in physical function remained at 12 months [difference in means 4.4 (95% confidence interval -1.7 to 10.5)]. One or more of the pre-defined measures of a worsening condition in participants during treatment, combining therapist and patient reports, were met by 39 (25%) participants in the Fatigue In Teenagers on the interNET in the National Health Service group and 42 (26%) participants in the Activity Management group. A small gain was observed for the Fatigue In Teenagers on the interNET in the National Health Service group compared to Activity Management in quality-adjusted life-years (0.002, 95% confidence interval -0.041 to 0.045). From an National Health Service perspective, the costs were £1047.51 greater in the Fatigue In Teenagers on the interNET in the National Health Service group (95% confidence interval £624.61 to £1470.41). At a base cost-effectiveness threshold of £20,000 per quality-adjusted life-year, the incremental cost-effectiveness ratio was £457,721 with incremental net benefit of -£1001 (95% confidence interval -£2041 to £38). Conclusion: At 6 months post randomisation, compared with Activity Management, Fatigue In Teenagers on the interNET in the National Health Service improved physical function and school attendance. The additional cost of Fatigue In Teenagers on the interNET in the National Health Service and limited sustained impact mean it is unlikely to be cost-effective. Trial registration: This trial is registered as ISRCTN18020851. Funding: This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 14/192/109) and is published in full in Health Technology Assessment; Vol. 28, No. 70. See the NIHR Funding and Awards website for further award information.

Why did we do the study? The best evidence for the treatment of adolescents with myalgic encephalomyelitis/chronic fatigue syndrome is cognitive­behavioural therapy for fatigue delivered in person. In the United Kingdom, most adolescents with myalgic encephalomyelitis/chronic fatigue syndrome cannot get this specialist treatment where they live. Fatigue In Teenagers on the interNET in the National Health Service is an online treatment using cognitive­behavioural therapy designed for myalgic encephalomyelitis/chronic fatigue syndrome, which has been shown to work in the Netherlands. To find out if Fatigue In Teenagers on the interNET in the National Health Service would be beneficial in the United Kingdom, we compared Fatigue In Teenagers on the interNET in the National Health Service to Activity Management. Activity Management is the treatment most often offered to children and young people with myalgic encephalomyelitis/chronic fatigue syndrome in the United Kingdom, and aims to avoid peaks in activity (sometimes called 'pacing'). What was the question? Does Fatigue In Teenagers on the interNET in the National Health Service lead to greater improvements in children and young people with myalgic encephalomyelitis/chronic fatigue syndrome when compared to Activity Management, when both interventions are delivered remotely? What did we do? We compared Fatigue In Teenagers on the interNET in the National Health Service and Activity Management in two comparable groups of children, and measured physical function at 6 months as the main indication of improvement. We measured how much the treatments cost and we asked children and young people, their parents and treatment providers what they thought about the two interventions. What did we find? At 6 months, adolescents saw greater improvements in physical function, and attended half a day more school per week, with Fatigue In Teenagers on the interNET in the National Health Service compared to Activity Management. Both interventions were associated with improvements over 12 months, with there being no clear difference between them after that time. However, the Fatigue In Teenagers on the interNET in the National Health Service treatment was more expensive. What does this mean? We have shown that cognitive­behavioural therapy for fatigue can be provided online to children as Fatigue In Teenagers on the interNET in the National Health Service, leading to faster improvement in physical function and greater school attendance compared to Activity Management. However, Fatigue In Teenagers on the interNET in the National Health Service is expensive and is unlikely to be good value for money.

No reduced serum serotonin levels in patients with post-acute sequelae of COVID-19.

PURPOSE: Approximately 10-20% of patients previously infected with SARS-CoV-2 experience post-acute sequelae of COVID-19 (PASC), presenting with fatigue and neurocognitive dysfunction along various other symptoms. Recent studies suggested a possible role of a virally induced decrease in peripheral serotonin concentration in the pathogenesis of PASC. We set out to verify this finding in an independent and well-defined cohort of PASC patients from our post-COVID-19 outpatient clinic. METHODS: We performed a retrospective case-control study including 34 confirmed PASC patients and 14 healthy controls. Clinical assessment encompassed physician examination as well as questionnaire based evaluation. Eligibility required ongoing symptoms for at least 6 months post-PCR-confirmed infection, relevant fatigue (CFS ≥ 4), and no other medical conditions. Serum serotonin was determined by LC-MS/MS technique. RESULTS: Serum serotonin levels in PASC patients did not significantly differ from healthy controls. Most subjects had normal serotonin levels, with no subnormal readings. Subgroup analyses showed no significant differences in serotonin levels based according to predominant fatigue type, high overall fatigue score or depression severity. CONCLUSION: We postulate that peripheral serotonin is no reliable biomarker for PASC and that it should not be used in routine diagnostic. Therapy of PASC with serotonin-reuptake inhibitors or tryptophane supplementation should not be based solely on the assumption of lowered serotonin levels.

Six-Week Supplementation with Creatine in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): A Magnetic Resonance Spectroscopy Feasibility Study at 3 Tesla.

BACKGROUND: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a chronic medical condition with no specific pharmacological treatment. Creatine, a nutrient essential for maintaining energy homeostasis in the cells, is a candidate for interventions in ME/CFS. METHODS: Fourteen participants with ME/CFS received supplementation with 16 g creatine monohydrate for 6 weeks. Before starting creatine and on the last day of treatment, participants underwent brain magnetic resonance spectroscopy (MRS) scanning of the pregenual anterior cingulate cortex (pgACC) and dorsolateral prefrontal cortex (DLPFC), followed by symptom, cognition, and hand-grip strength assessments. RESULTS: Eleven participants completed the study. Creatine treatment increased creatine concentration in both the pgACC and DLPFC (p = 0.004 and 0.012, respectively), decreased fatigue and reaction time (RT) on congruent and incongruent trials of the Stroop test (p = 0.036 and 0.014, respectively), and increased hand-grip strength (p = 0.0004). There was a positive correlation between increases in pgACC creatine and changes in RT on Stroop congruent and incongruent trials (p = 0.048 and p = 0.022, respectively). Creatine was well tolerated, and none of the participants stopped treatment. CONCLUSION: Creatine supplementation over six weeks in ME/CFS patients increased brain creatine and improved fatigue and some aspects of cognition. Despite its methodological limitations, this study encourages placebo-controlled investigations of creatine treatment in ME/CFS.

The persistence of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) after SARS-CoV-2 infection: A systematic review and meta-analysis.

OBJECTIVES: Long COVID-19 (LC) patients experience a number of chronic idiopathic symptoms that are highly similar to those of post-viral myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). We have therefore performed a systematic review and meta-analysis to determine the proportion of LC patients that satisfy ME/CFS diagnostic criteria. METHODS: Clinical studies published between January 2020 and May 2023 were identified using the PubMed, Web of Science, Embase and CINAHL databases. Publication inclusion/exclusion criteria were formulated using the global CoCoPop framework. Data were pooled using a random-effects model with a restricted maximum-likelihood estimator. Study quality was assessed using the Joanna Briggs Institute critical assessment tool. RESULTS: We identified 13 eligible studies that reported a total of 1973 LC patients. Our meta-analysis indicated that 51% (95% CI, 42%-60%) of LC patients satisfied ME/CFS diagnostic criteria, with fatigue, sleep disruption, and muscle/joint pain being the most common symptoms. Importantly, LC patients also experienced the ME/CFS hallmark symptom, post-exertional malaise. CONCLUSIONS: Our study not only demonstrates that LC patients exhibit similar symptom clusters to ME/CFS, but that approximately half of LC patients satisfy a diagnosis of ME/CFS. Our findings suggest that current ME/CFS criteria could be adapted to the identification of a subset of LC patients that may facilitate the standardised diagnosis, management and the recruitment for clinical studies in the future.

Chronic Overlapping Pain Conditions in people with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): a sample from the Multi-site Clinical Assessment of ME/CFS (MCAM) study.

BACKGROUND: Chronic overlapping pain conditions (COPCs), pain-related conditions that frequently occur together, may occur in patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and could impact illness severity. This study aimed to identify comorbid COPCs in patients with ME/CFS and evaluate their impact on illness severity. METHODS: We used data from 923 participants in the Multi-Site Clinical Assessment of ME/CFS study, conducted in seven U.S. specialty clinics between 2012 and 2020, who completed the baseline assessment (595 ME/CFS and 328 healthy controls (HC)). COPCs included chronic low back pain (cLBP), chronic migraine/headache (cMHA), fibromyalgia (FM), interstitial cystitis/irritable bladder (IC/IB), irritable bowel syndrome (IBS), temporomandibular disorder (TMD). Illness severity was assessed through questionnaires measuring symptoms and functioning. Multivariate analysis of variance and analysis of covariance models were used for analyses. Log-binomial regression analyses were used to compute prevalence of COPCs and prevalence ratios (PR) between groups with 95% confidence intervals. Both unadjusted and adjusted results with age and sex are presented. RESULTS: 76% of participants with ME/CFS had at least one COPCs compared to 17.4% of HC. Among ME/CFS participants, cMHA was most prevalent (48.1%), followed by FM (45.0%), cLBP (33.1%), and IBS (31.6%). All individual COPCs, except TMD, were significantly more frequent in females than males. The unadjusted PR (ME/CFS compared to HC) was highest for FM [147.74 (95% confidence interval (CI) = 20.83-1047.75], followed by cLBP [39.45 (12.73-122.27)], and IC/IB [13.78 (1.88-101.24)]. The significance and order did not change after age and sex adjustment. The COPC comorbidities of cLBP and FM each had a significant impact on most health measures, particularly in pain attributes (Cohen's d effect size 0.8 or larger). While the impact of COPC comorbidities on non-pain attributes and quality of life measures was less pronounced than that on pain, statistically significant differences between ME/CFS participants with and without COPCs were still evident. CONCLUSIONS: More than 75% of ME/CFS participants had one or more COPCs. Multiple COPCs further exacerbated illness severity, especially among females with ME/CFS. Assessment and management of COPCs may help improve the health and quality of life for patients with ME/CFS.

Predictors of treatment response trajectories to cognitive behavioral therapy for chronic fatigue syndrome: A cohort study.

BACKGROUND: The response to cognitive behavioral therapy (CBT) for chronic fatigue syndrome (CFS) varies greatly between patients, but predictors of treatment success remain to be elucidated. We aimed to identify patient subgroups based on fatigue trajectory during CBT, identify pre-treatment predictors of subgroup membership, and disentangle the direction of predictor - outcome relationships over time. METHODS: 297 individuals with CFS were enrolled in a standardized CBT program consisting of 17 sessions, with session timing variable between participants. Self-reported levels of fatigue, depressive, anxiety, and somatic symptoms, perceived stress, and positive affect were collected pre-treatment, and after 3, 10, and 15 sessions. Latent Class Growth Analysis (LCGA) was used to identify subgroups based on fatigue trajectories and baseline predictors of group membership. Cross-lagged structural equation models were used to disentangle predictor-outcome relationships. RESULTS: LCGA identified four fatigue trajectory subgroups, which were labelled as "no improvement" (23 %), "weak improvement" (45 %), "moderate improvement" (23 %), and "strong improvement" (9 %) classes. Higher pre-treatment levels of depressive, anxiety, and somatic symptoms, stress, and lower levels of positive affect predicted membership of the "no improvement" subgroup. Reductions in anxiety preceded reductions in fatigue, while the depressive symptoms - fatigue relationship was bidirectional. CONCLUSIONS: On a group level, there were statistically significant reductions in fatigue after 15 sessions of CBT, with important individual differences in treatment response. Higher pre-treatment levels of anxious, depressive, and somatic symptoms and perceived stress are predictors of lack of response, with reductions in anxiety and stress preceding improvements in fatigue.

Hypothalamus Connectivity in Adolescent Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Adolescent Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a disabling illness of unknown etiology. Increasing evidence suggests hypothalamic involvement in ME/CFS pathophysiology, which has rarely been explored using magnetic resonance imaging (MRI) in the condition. This work aimed to use MRI to examine hypothalamus connectivity in adolescents with ME/CFS and explore how this relates to fatigue severity and illness duration. 25 adolescents with ME/CFS and 23 healthy controls completed a neuroimaging protocol consisting of structural and multishell diffusion-weighted imaging sequences, in addition to the PedsQL Multidimensional Fatigue Scale to assess fatigue severity. Information about illness duration was acquired at diagnosis. Preprocessing and streamlines tractography was performed using QSIPrep combined with a custom parcellation scheme to create structural networks. The number (degree) and weight (strength) of connections between lateralized hypothalamus regions and cortical and subcortical nodes were extracted, and relationships between connectivity measures, fatigue severity, and illness duration were performed using Bayesian regression models. We observed weak-to-moderate evidence of increased degree, but not strength, of connections from the bilateral anterior-inferior (left: pd [%] = 99.18, median [95% CI] = -22.68[-40.96 to 4.45]; right: pd [%] = 99.86, median [95% CI] = -23.35[-38.47 to 8.20]), left anterior-superior (pd [%] = 99.33, median [95% CI] = -18.83[-33.45 to 4.07]) and total left hypothalamus (pd [%] = 99.44, median [95% CI] = -47.18[-83.74 to 11.03]) in the ME/CFS group compared with controls. Conversely, bilateral posterior hypothalamus degree decreased with increasing ME/CFS illness duration (left: pd [%] = 98.13, median [95% CI]: -0.47[-0.89 to 0.03]; right: pd [%] = 98.50, median [95% CI]:-0.43[-0.82 to 0.05]). Finally, a weak relationship between right intermediate hypothalamus connectivity strength and fatigue severity was identified in the ME/CFS group (pd [%] = 99.35, median [95% CI] = -0.28[-0.51 to 0.06]), which was absent in controls. These findings suggest changes in hypothalamus connectivity may occur in adolescents with ME/CFS, warranting further investigation.

Exploring the role of galectin-9 and artemin as biomarkers in long COVID with chronic fatigue syndrome: links to inflammation and cognitive function.

This study aimed to assess plasma galectin-9 (Gal-9) and artemin (ARTN) concentrations as potential biomarkers to differentiate individuals with Long COVID (LC) patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) from SARS-CoV-2 recovered (R) and healthy controls (HCs). Receiver operating characteristic (ROC) curve analysis determined a cut-off value of plasma Gal-9 and ARTN to differentiate LC patients from the R group and HCs in two independent cohorts. Positive correlations were observed between elevated plasma Gal-9 levels and inflammatory markers (e.g. SAA and IP-10), as well as sCD14 and I-FABP in LC patients. Gal-9 also exhibited a positive correlation with cognitive failure scores, suggesting its potential role in cognitive impairment in LC patients with ME/CFS. This study highlights plasma Gal-9 and/or ARTN as sensitive screening biomarkers for discriminating LC patients from controls. Notably, the elevation of LPS-binding protein in LC patients, as has been observed in HIV infected individuals, suggests microbial translocation. However, despite elevated Gal-9, we found a significant decline in ARTN levels in the plasma of people living with HIV (PLWH). Our study provides a novel and important role for Gal-9/ARTN in LC pathogenesis.

Immunometabolic changes and potential biomarkers in CFS peripheral immune cells revealed by single-cell RNA sequencing.

The pathogenesis of Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) remains unclear, though increasing evidence suggests inflammatory processes play key roles. In this study, single-cell RNA sequencing (scRNA-seq) of peripheral blood mononuclear cells (PBMCs) was used to decipher the immunometabolic profile in 4 ME/CFS patients and 4 heathy controls. We analyzed changes in the composition of major PBMC subpopulations and observed an increased frequency of total T cells and a significant reduction in NKs, monocytes, cDCs and pDCs. Further investigation revealed even more complex changes in the proportions of cell subpopulations within each subpopulation. Gene expression patterns revealed upregulated transcription factors related to immune regulation, as well as genes associated with viral infections and neurodegenerative diseases.CD4+ and CD8+ T cells in ME/CFS patients show different differentiation states and altered trajectories, indicating a possible suppression of differentiation. Memory B cells in ME/CFS patients are found early in the pseudotime, indicating a unique subtype specific to ME/CFS, with increased differentiation to plasma cells suggesting B cell overactivity. NK cells in ME/CFS patients exhibit reduced cytotoxicity and impaired responses, with reduced expression of perforin and CD107a upon stimulation. Pseudotime analysis showed abnormal development of adaptive immune cells and an enhanced cell-cell communication network converging on monocytes in particular. Our analysis also identified the estrogen-related receptor alpha (ESRRA)-APP-CD74 signaling pathway as a potential biomarker for ME/CFS in peripheral blood. In addition, data from the GSE214284 database confirmed higher ESRRA expression in the monocyte cell types of male ME/CFS patients. These results suggest a link between immune and neurological symptoms. The results support a disease model of immune dysfunction ranging from autoimmunity to immunodeficiency and point to amyloidotic neurodegenerative signaling pathways in the pathogenesis of ME/CFS. While the study provides important insights, limitations include the modest sample size and the evaluation of peripheral blood only. These findings highlight potential targets for diagnostic biomarkers and therapeutic interventions. Further research is needed to validate these biomarkers and explore their clinical applications in managing ME/CFS.

Risk of chronic fatigue syndrome after COVID-19: A retrospective cohort study of 3227281 patients.

BACKGROUND: Many patients who recovered from COVID-19 still suffer from chronic fatigue syndrome (CFS). It was observed that patients with comorbidities were more prone to developing CFS. This research investigates the risk of post-COVID-19 CFS to assist healthcare professionals in reducing the risk of CFS. METHODS: A retrospective cohort study is conducted to investigate the risk of post-COVID-19 CFS based on the TriNetX-sourced electronic health records. Factors including age, sex, race, vaccination, and severity of COVID-19 are analysed. Propensity score matching was applied to balance COVID-19 and non-COVID-19 cohorts. Kaplan-Meier analysis and Cox proportional hazard model were used to perform the relationship between COVID-19 and CFS risk. RESULTS: This research involved 3227281 patients with COVID-19 and 3227281 with non-COVID-19 between 1st January 2020 and 31st December 2023. The incidence of CFS was higher in the COVID-19 group compared to the non-COVID-19 group at 1 follow-up intervals (HR 1.59, 95 % CI = 1.54-1.63). Subgroup analysis revealed increased CFS risk across different age groups (>18), sexes, races, and comorbid conditions, with notable variations. CONCLUSIONS: COVID-19 patients have a higher risk of developing CFS compared to individuals without COVID-19. The increased risk is particularly significant in adults aged 18 years and older.

Autoimmunity's enigmatic role: exploring the connection with myalgic encephalomyelitis/chronic fatigue syndrome.

BACKGROUND: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complicated, heterogeneous condition distinguished by post-exertional neuroimmune exhaustion and multisystem symptoms. Its complexity poses challenges for physicians, researchers and those inflicted by its presence. Due to conflicting evidence and limiting consensus, the association and contribution autoimmunity serves in the pathophysiology or aetiology of ME/CFS is yet to be confirmed. This systematic review synthesises the currently available data to clarify the role autoimmunity has in the pathogenesis of ME/CFS and explore the therapeutic limitations. METHODS: This systematic review was conducted in accordance with the PRISMA and Cochrane guidelines. Full-text articles containing the primary key terms "Autoimmunity/Autoimmune" and "ME/CFS" were included provided their suitability to the inclusion and exclusion criteria. RESULTS: Ten publications investigating the role of autoimmunity in ME/CFS were examined. One investigated the role of cytokine signalling; Three investigated the genetic nature of autoimmunity in ME/CFS patients; One examined the immune lineage of ME/CFS patients; Six investigated the presence and role of autoantibodies in ME/CFS patients. CONCLUSION: The findings generated from this systematic review highlight inconsistent and insufficient evidence to classify ME/CFS as an autoimmune disease. Additionally, it further emphasises the complexity of ME/CFS and highlights the challenges in distinguishing autoreactivity from deregulatory processes. Future research is urgently needed to advance the development of diagnostic and treatment strategies. PROSPERO REGISTRATION CODE: CRD42024533447.

Genetic variants associated with chronic fatigue syndrome predict population-level fatigue severity and actigraphic measurements.

STUDY OBJECTIVES: The diagnosis of myalgic encephalomyelitis/chronic fatigue syndrome (CFS) is based on a constellation of symptoms which center around fatigue. However, fatigue is commonly reported in the general population by people without CFS. Does the biology underlying fatigue in patients with CFS also drive fatigue experienced by individuals without CFS? METHODS: We used UK Biobank actigraphy data to characterize differences in physical activity patterns and daily temperature rhythms between participants diagnosed with CFS compared to controls. We then tested if single nucleotide variants (SNVs) previously associated with CFS are also associated with the variation of these actigraphic CFS correlates and/or subjective fatigue symptoms in the general population. RESULTS: Participants diagnosed with CFS (n = 295) had significantly decreased overall movement (Cohen's d = 0.220, 95% CI of -0.335 to -0.106, p-value = 2.42x10-15), lower activity amplitudes (Cohen's d = -0.377, 95% CI of -0.492 to -0.262, p-value = 1.74x10-6), and lower wrist temperature amplitudes (Cohen's d = -0.173, 95% CI of -0.288 -0.059, p-value = 0.002) compared to controls (n = 63,133). Of 30 tested SNVs associated in the literature with CFS, one was associated in the control population with subjective fatigue and one with actigraphic measurements (FDR < 0.05). CONCLUSIONS: The genetic overlap of CFS risk with actigraphy and subjective fatigue phenotypes suggests that some biological mechanisms underlying pathologic fatigue in CFS patients also underlie fatigue symptoms at a broader population level. Therefore, understanding the biology of fatigue in general may inform our understanding of CFS pathophysiology.

Trends and Hotspots in the Health Economics Evaluation of Chronic Fatigue Syndrome.

Objective: To explore the research trends and hotspots of health economics evaluations of patients with chronic fatigue syndrome. Methods: To explore the research trends and hotspots of health economics evaluations of chronic fatigue syndrome, 180 articles published between 1991 and 2024 were visualized and analyzed via CiteSpace 6.3 software. R3 and VOSviewer1.6.20 and R4.3.3. The content includes annual publication volume, journal distribution, author country, publishing organization, author collaboration, citation analysis, and keyword analysis in 7 aspects. Results: Fewer studies have evaluated the health economics of individuals with chronic fatigue syndrome in China and abroad, Chinese studies are especially rare, and research results in the UK are mostly found in other countries. Moreover, cooperation and linkages between institutions, as well as between authors, are not yet strong. Conclusion: The hotspot of health economics evaluation methods in this field is cost-effectiveness analysis, and the hotspot of diagnosis and treatment methods is cognitive‒behavioral therapy. We also found that chronic fatigue syndrome may also have a strong potential association with depression from the perspective of health economics. Health economic evaluations of multiple treatments should be conducted simultaneously to increase attention to this field and provide a reference basis for low-cost and high-quality diagnostic and treatment programs.

A pilot cross-sectional investigation of symptom clusters and associations with patient-reported outcomes in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Post COVID-19 Condition.

BACKGROUND: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is associated with long-term disability and poor quality of life (QoL). Cardinal ME/CFS symptoms (including post-exertional malaise, cognitive dysfunction and sleep disturbances) have been observed in Post COVID-19 Condition (PCC). To gain further insight into the potential role of ME/CFS as a post-COVID-19 sequela, this study investigates associations between symptoms and patient-reported outcomes, as well as symptom clusters. METHODS: Participants included Australian residents aged between 18 and 65 years formally diagnosed with ME/CFS fulfilling the Canadian or International Consensus Criteria or PCC meeting the World Health Organization case definition. Validated, self-administered questionnaires collected participants' sociodemographic and illness characteristics, symptoms, QoL and functional capacity. Associations between symptoms and patient-reported outcomes were investigated with multivariate linear regression models. Hierarchical cluster analysis was performed to identify symptom clusters. RESULTS: Most people with ME/CFS (pwME/CFS) and people with PCC (pwPCC) were female (n = 48/60, 80.0% and n = 19/30, 63.3%, respectively; p = 0.12). PwME/CFS were significantly younger (x̄=41.75, s = 12.91 years) than pwPCC (x̄=48.13, s =10.05 years; p =0.017). Autonomic symptoms (notably dyspnoea) were associated with poorer scores in most patient-reported outcome domains for both cohorts. None of the four symptom clusters identified were unique to ME/CFS or PCC. Clusters were largely delineated by the presence of gastrointestinal and neurosensory symptoms, illness duration, ME/CFS criteria met and total symptoms. CONCLUSIONS: Illness duration may explain differences in symptom burden between pwME/CFS and pwPCC. PCC diagnostic criteria must be refined to distinguish pwPCC at risk of long-term ME/CFS-like illness and subsequently deliver necessary care and support.

Post COVID-19 Condition (PCC), or Long COVID, refers to the ongoing symptoms experienced after acute COVID-19 illness. The symptoms reported by people with PCC (pwPCC) resemble Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). However, existing diagnostic criteria for PCC are broad and cannot discern PCC subtypes (such as pwPCC experiencing ME/CFS-like illness), which may require different approaches to care. This study contributes to improving PCC case criteria and approaches to care for both ME/CFS and PCC by investigating the relationships between symptoms and patient-reported outcomes among pwPCC and people with ME/CFS (pwME/CFS).For both cohorts, symptoms had a negative relationship with all aspects of health. Autonomic symptoms, notably breathing issues, returned the most negative associations. Pain, flu-like symptoms and lack of temperature control appeared more burdensome among pwPCC. These symptoms may signify the early stages of ME/CFS. Symptom clusters were also identified for the first time among a combined cohort of pwME/CFS and pwPCC in this study. Importantly, none of the symptom clusters were specific to ME/CFS or PCC. Instead, symptom clusters were defined by the prevalence of gastrointestinal and neurosensory symptoms, illness duration, ME/CFS criteria met and the total number of symptoms.This study suggests that the few differences between ME/CFS and PCC may be explained by illness duration. These findings further implicate ME/CFS as a potential post-COVID-19 outcome. As ME/CFS is associated with profound reductions in quality of life and functioning, identifying pwPCC experiencing ME/CFS-like illness through refined diagnostic criteria must be prioritised to ensure the delivery of necessary care.

[Chronic fatigue syndrome in children]. / Sindrom khronicheskoi ustalosti u detei.

The article provides an overview of scientific publications devoted to the study of chronic fatigue syndrome (CFS). The results of works devoted to the study of the epidemiology of this pathology in childhood and adults are considered. The authors presented different views on the etiology and basic mechanisms of the pathogenesis of CFS, current diagnostic criteria for this disease and features of clinical manifestations in childhood. Special attention is paid to the description of the main neurocognitive deficits observed in CFS in children. Also reviewed are studies aimed at finding effective approaches to the treatment of CFS in children.

[Association of inflammation and chronic fatigue syndrome in patients with Parkinson's disease]. / Assotsiatsiya vospaleniya i sindroma khronicheskoi ustalosti pri bolezni Parkinsona.

OBJECTIVE: To study the prevalence of chronic fatigue syndrome (CFS) and association of CFS with other clinical and neuropsychological manifestations of Parkinson's disease (PD) as well as with serum inflammatory markers and genetic polymorphisms. MATERIAL AND METHODS: The study included 533 patients with PD. All patients underwent clinical, neurological examination and neuropsychological testing using validated questionnaires: MoCA test, HADS, BDI-II, the Fatigue Severity Scale (FSS). Serum concentrations of inflammatory markers (slCAM-1, sVCAM-1, NCAM, CCL5, PAI-1 and MPO) were assessed in 144 patients using xMAP technology. A case-control study of CCL5 (rs2107538) and PAI-1 (rs2227631) gene polymorphisms was performed in connection with PD development and in groups differing in the presence/absence of CFS in PD. In addition, the relationship of these polymorphisms with variability in the levels of the corresponding proteins in the blood serum of patients was studied. Genotyping of CCL5 (rs2107538) and PAI-1 (rs2227631) polymorphisms was performed using real-time PCR with TaqMan probes. RESULTS: CFS is common in 66.7% of patients in the PD group. In addition, non-motor symptoms (emotional-affective, cognitive, autonomic disorders and pain) were more common in patients with CFS. A strong correlation has been established between the severity of CFS assessed with FSS and serum concentrations of CCL5, sVCAM-1, NCAM and slCAM-1. In newly diagnosed patients with PD who were not taking antiparkinsonian drugs at the time of the study and had CFS, higher correlations were noted between inflammatory markers and the severity of CFS manifestations. When comparing the distribution of genotypes and alleles of CCL5 (rs2107538) and PAI-1 (rs2227631) polymorphisms, some differences were found between the groups of patients with PD and controls (p<0.05). However, these polymorphisms did not affect the variability of serum protein levels CCL5 and PAI-1, respectively, nor did they affect the development of CFS in patients with PD. CONCLUSION: CFS is common in PD, and patients with PD and CFS are characterized by elevated levels of serum markers CCL5, sVCAM-1, slCAM-1 and NCAM, suggesting the importance of the inflammatory component in the development of neurodegenerative disease. In addition, the clinical course of PD in patients with CFS is aggravated by other non-motor manifestations, including emotional-affective, cognitive, autonomic disorders and pain. These results highlight the potential contribution of an inflammatory component to the development of fatigue associated with PD, starting from the earliest clinical stages of the disease.

Assessment of the therapeutic potential of salubrinal for ME/CFS and long-COVID.

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a chronic debilitating condition with no cure that shares commonality with long-COVID. This review examines current understanding of long-COVID symptoms, characteristics of the affected population, the connection with ME/CFS, and the potential for salubrinal, an agent known for its influence on cellular stress pathways, to mitigate these disorders It also describes the historical development and mechanism of action of salubrinal, to mitigate endoplasmic reticulum (ER)/cellular stress responses, that could potentially contribute to symptom improvement in both ME/CFS and long-COVID patients. Further research and clinical trials are warranted to advance our understanding of the potential role of salubrinal in improving the quality of life for individuals with long-COVID-related ME/CFS symptoms as well as ME/CFS patients.

Adrenergic dysfunction in patients with myalgic encephalomyelitis/chronic fatigue syndrome and fibromyalgia: A systematic review and meta-analysis.

BACKGROUND: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and fibromyalgia (FM) are comorbid disorders with overlapping symptoms. Research highlights autonomic dysfunction compared to healthy individuals, particularly involving the sympathetic branch. While past reviews focused on neurophysiological assessments, this systematic review summarises biological adrenergic markers, offering deeper insights into the observed sympathetic dysfunction in ME/CFS and FM aiming to identify targetable pathophysiological mechanisms. METHODS: A systematic search was performed on PubMed, Web of Science, Embase and Scopus. Studies investigating peripheral biological markers of adrenergic function in patients with ME/CFS or FM compared to healthy controls at baseline were included. Meta-analyses were performed using R statistical software. RESULTS: This meta-analysis of 37 studies, encompassing 543 ME/CFS patients and 651 FM patients, compared with 747 and 447 healthy controls, respectively, revealed elevated adrenaline (SMD = .49 [.31-.67]; Z = 5.29, p < .01) and ß1 adrenergic receptor expression (SMD = .79 [.06-1.52]; Z = 2.13; p = .03) in blood of ME/CFS patients at rest. Additionally, patients with ME/CFS had a greater increase in the expression of α2A adrenergic receptor (AR, SMD = .57 [.18-.97]; Z = 2.85, p < .01), ß2 AR (SMD = .41 [.02-.81]; Z = 2.04; p = .04) and COMT (SMD = .42 [.03-.81]; Z = 2.11; p = .03) after exercise and an increased response of noradrenaline to an orthostatic test (SMD = .11 [-.47 to -.70]; Z = 2.10; p = .04), both found in blood. FM patients showed no significant differences at baseline but exhibited a diminished adrenaline response to exercise (SMD = -.79 [-1.27 to -.30]; Z = -3.14; p < .01). CONCLUSION: This systematic review and meta-analysis revealed adrenergic dysfunction mainly in patients with ME/CFS. Higher baseline adrenaline levels and atypical responses to exercise in ME/CFS indicate that sympathetic dysfunction, underscored by adrenergic abnormalities, is more involved in the pathophysiology of ME/CFS rather than FM.