ME/CFS and Long COVID Demonstrate Similar Bioenergetic Impairment and Recovery Failure on Two-Day Cardiopulmonary Exercise Testing

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and Long Covid are characterized by post-exertional malaise (PEM). Similarities in disease presentation suggest important commonalities in bioenergetic impairment, but this hypothesis has not been demonstrated. The metabolic underpinnings of each disease can be elucidated by two cardiopulmonary exercise tests (CPET) administered 24 hours apart. This retrospective study examined physiological responses on two-day CPET in people with ME/CFS (63 females and 21 males), Long Covid (52 females and 27 males), and matched non-disabled control participants (51 females and 20 males).

Data were analyzed within sexes using repeated measures analysis of variance. All participants met maximal effort criteria. There were significant reductions in oxygen consumption (O₂) and workload at the ventilatory anaerobic threshold (VAT) in both patient groups compared to non-disabled controls, with larger effect sizes at VAT than at peak exertion. Performance decrements were observed in both sexes.

Females exhibited more pronounced abnormalities and significant group by test effects. No significant differences were observed between patient groups. Severe disability based on impaired O₂ was prevalent in both patient groups. Hemodynamic and ventilatory measures were within normal ranges. ME/CFS and Long Covid both involve a functionally significant bioenergetic failure complicated by inadequate post-exertional recovery, which is similar between the conditions and unexplained by hemodynamic and ventilatory changes.

Findings support the utility of two-day CPET as an objective measure of PEM and functional impairment. Future studies may integrate mechanistic biomarkers with two-day CPET as trial endpoints and to establish likely responses to treatments for PEM.

Source: Todd Davenport, Staci Stevens, Jared Stevens et al. ME/CFS and Long COVID Demonstrate Similar Bioenergetic Impairment and Recovery Failure on Two-Day Cardiopulmonary Exercise Testing, 22 January 2026, PREPRINT (Version 1) available at Research Square [https://doi.org/10.21203/rs.3.rs-8606329/v1] https://www.researchsquare.com/article/rs-8606329/v1 (Full text available as PDF file)

Contested and neglected: Social and medical marginalization in severe Chronic Fatigue Syndrome

Highlights:

  • Severe ME/CFS patients face deep social, medical, and structural exclusion.
  • Delegitimation of illness leads to isolation, distress, and denied support.
  • Gendered stigma shapes how women’s pain is dismissed in health care.
  • Twitter (now X) offers access to the voices of an otherwise unreachable patient group.
  • This study urges reforms in care, disability access, and illness recognition.

Abstract:

This study addresses the persistent invisibility of people with severe Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) in research by centering their voices and examining how social and institutional forces shape their lives. As a medically contested illness, ME/CFS—especially in its severe form—renders patients both physically incapacitated and socially invisible.
Drawing on qualitative content analysis of 342 tweets under the hashtag #severeME, we identify how contested legitimacy, gendered stigma, and systemic marginalization structure the daily realities of 161 individuals with severe ME/CFS or their caregivers. Our findings highlight profound functional debilitation, emotional isolation, and exclusion from care and disability systems. We argue for the urgent need to legitimize contested illnesses, reform models of care, and extend disability protections to restore dignity and support to this neglected population.
Source: Bita Nezamdoust, Erin Ruel. Contested and neglected: Social and medical marginalization in severe Chronic Fatigue Syndrome. Social Science & Medicine, Volume 388, 2026, 118766. ISSN 0277-9536. https://www.sciencedirect.com/science/article/pii/S0277953625010974 (Full text)

Integrated immune, hormonal, and transcriptomic profiling reveals sex-specific dysregulation in long COVID patients with ME/CFS

Abstract:

Long COVID (LC) manifests with sex-specific differences, particularly in those with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Our study reveals that female LC patients (LCF) with ME/CFS show a shift toward myelopoiesis, reduced lymphocytes, increased neutrophils/monocytes, and depleted regulatory T cells-suggesting persistent immune activation. Elevated CD71+ erythroid cells and disrupted erythropoiesis contribute to fatigue and tissue damage in LCF.

Cytokine profiling indicates a stronger pro-inflammatory response in LCF compared to males (LCM), along with markers of gut barrier dysfunction. Hormonal analysis shows reduced testosterone in LCF and estradiol in LCM. Transcriptomic data reveal neuroinflammatory signatures in LCF, potentially explaining cognitive symptoms. We also identify biomarkers that distinguish LCF from LCM and correlate with sex-specific clinical symptoms.

Overall, LC with ME/CFS is characterized by sex-specific immune, hormonal, and transcriptional alterations, with females exhibiting more severe inflammation. These insights underscore the need for sex-tailored interventions, including consideration of hormone replacement therapy.

Source: Shahbaz S, Osman M, Syed H, Mason A, Rosychuk RJ, Cohen Tervaert JW, Elahi S. Integrated immune, hormonal, and transcriptomic profiling reveals sex-specific dysregulation in long COVID patients with ME/CFS. Cell Rep Med. 2025 Nov 7:102449. doi: 10.1016/j.xcrm.2025.102449. Epub ahead of print. PMID: 41205594. https://www.cell.com/cell-reports-medicine/fulltext/S2666-3791(25)00522-1 (Full text)

Autonomic symptom burden, comorbidities and quality of life in women with Hypermobility Spectrum Disorders and hypermobile Ehlers-Danlos syndrome

Abstract:

Background: Hypermobility Spectrum Disorders (HSD) and hypermobile Ehlers-Danlos syndrome (h-EDS) are multisystemic connective tissue disorders involving joint hypermobility and numerous other manifestations. Autonomic dysfunction, chronic pain, and chronic fatigue are known comorbidities of HSD and h-EDS that can affect patient quality of life (QoL), but there are limited data on the severity of autonomic symptoms, prevalence of comorbid conditions and QoL in patients with HSD/h-EDS.

Methods: We utilized the Composite Autonomic Symptom Scale (COMPASS-31) to assess autonomic symptom severity, Short-Form 36 (SF-36) to assess QoL, and the Beck Depression Inventory Second Edition (BDI-II) in a cohort of women with physician-diagnosed HSD or h-EDS, who completed these questionnaires anonymously.

Results: 84 women (mean age of 37.1 ± 8.4 years) completed the study. 58.3 % reported having physician-diagnosed postural orthostatic tachycardia syndrome (POTS), 32.1 % had mast cell activation syndrome (MCAS), 54.8 % had migraine, 26.2 % had myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and 98.8 % reported experiencing chronic pain. Importantly, 25 % of patients reported having all three diagnoses: HSD/h-EDS, POTS and MCAS. Mean COMPASS-31 score was 54.45 (range 18.79-80.93), indicating severe autonomic dysfunction, which was significantly higher than in patients with multiple sclerosis, diabetic neuropathy, scleroderma, and psoriatic arthritis as shown in prior studies. Mean SF-36 score was 32.38 (SD = 22.91) indicating poor QoL, which was worse than in patients with POTS, multiple sclerosis, rheumatoid arthritis, and lupus as determined by prior studies.

Conclusions: This study demonstrates that women with HSD/h-EDS experience severe autonomic dysfunction, chronic pain, chronic comorbid conditions and reduced QoL. More than half of participants in this cohort had POTS and migraine, with one in four having a clinical triad of HSD/h-EDS, POTS and MCAS.

Source: Collins Hutchinson ML, Liang E, Fuster E, Blitshteyn S. Autonomic symptom burden, comorbidities and quality of life in women with Hypermobility Spectrum Disorders and hypermobile Ehlers-Danlos syndrome. Auton Neurosci. 2025 Oct 14;262:103356. doi: 10.1016/j.autneu.2025.103356. Epub ahead of print. PMID: 41118678. https://pubmed.ncbi.nlm.nih.gov/41118678/

Exploratory study on autoantibodies to arginine-rich human peptides mimicking Epstein-Barr virus in women with post-COVID and myalgic encephalomyelitis/chronic fatigue syndrom

Abstract:

Introduction: Epstein-Barr virus (EBV) infection is a well-established trigger and risk factor for both myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and post-COVID syndrome (PCS). In previous studies, we identified elevated IgG responses to arginine-rich (poly-R) sequences within the EBV nuclear antigens EBNA4 and EBNA6 in post-infectious ME/CFS (piME/CFS). Building on these findings, this exploratory study examines IgG reactivity to poly-R-containing EBV-derived peptides and homologous human peptides in women with PCS and ME/CFS.

Methods: IgG reactivity to poly-R containing peptides derived from EBNA4 and EBNA6, and homologous human 15-mer peptides and the corresponding full-length proteins, was assessed using a cytometric bead array (CBA) and a multiplex dot-blot assay. Serum samples were analyzed from 45 female PCS patients diagnosed according to WHO criteria, including 26 who also met the Canadian Consensus criteria for ME/CFS (pcME/CFS), 36 female patients with non-COVID post-infectious ME/CFS (piME/CFS), and 34 female healthy controls (HC).

Results: Autoantibodies targeting poly-R peptide sequences of the neuronal antigen SRRM3, the ion channel SLC24A3, TGF-β signaling regulator TSPLY2, and the angiogenesis-related protein TSPYL5, as well as full-length α-adrenergic receptor (ADRA) proteins, were more frequently detected in patient groups. Several of these autoantibodies showed positive correlations with core symptoms, including autonomic dysfunction, fatigue, cognitive impairment, and pain.

Conclusion: This exploratory study identify autoantibodies directed against EBV mimicking arginine-rich sequences in human proteins, suggesting a potential role for molecular mimicry in the pathogenesis of PCS and ME/CFS.

Source: Hoheisel Friederike , Fleischer Kathrin Maria , Rubarth Kerstin , Sepúlveda Nuno , Bauer Sandra , Konietschke Frank , Kedor Peters Claudia , Stein Annika Elisa , Wittke Kirsten , Seifert Martina , Bellmann-Strobl Judith , Mautner Josef , Behrends Uta , Scheibenbogen Carmen , Sotzny Franziska. Exploratory study on autoantibodies to arginine-rich human peptides mimicking Epstein-Barr virus in women with post-COVID and myalgic encephalomyelitis/chronic fatigue syndrome. Frontiers in Immunology, Volume 16 – 2025. DOI=10.3389/fimmu.2025.1650948 ISSN=1664-3224 https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2025.1650948/full (Full text)

Endometriosis and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Systematic Review and Meta-Analysis

Abstract:

Background/Objectives: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and endometriosis are debilitating conditions that share overlapping features of chronic inflammation and immune dysregulation, yet their epidemiological relationship remains poorly characterized. The objective of this study was to investigate the association between ME/CFS and endometriosis, examining shared risk factors, clinical correlates, and epidemiological patterns.

Methods: We conducted a systematic review and meta-analysis. Two independent reviewers screened 236 records after duplicate removal, with seventeen studies undergoing full-text review and thirteen meeting inclusion criteria for meta-analysis. Data were extracted using standardized forms and analyzed using random-effects models in R, with heterogeneity assessed using I2 statistics and the risk of bias evaluated using the JBI critical appraisal tool.

Results: Our meta-analysis of five studies (n = 2261 participants) revealed that women with endometriosis had 2.79-fold higher odds (95% CI: 2.00-3.89) of developing ME/CFS compared to controls. Similarly, our fixed-effects meta-analysis of two studies assessing the association of ME/CFS and endometriosis yielded a pooled OR of 2.52 (95% CI: 2.45-2.60, p < 0.001). There was minimal statistical heterogeneity (I2 = 0.0%, p > 0.7969) for both meta-analyses.

Conclusions: This study demonstrates a significant bidirectional association between endometriosis and ME/CFS, driven by shared mechanisms of immune dysregulation and chronic inflammation. Despite high heterogeneity, the consistent effect sizes support clinical vigilance for comorbidity. Future research should prioritize standardized diagnostic criteria to elucidate causal pathways. These findings underscore the need for integrated care approaches to address overlapping symptomatology in affected patients.

Source: Compton S, Alkabalan R, Cadet J, Mastali A, Ramdass PVAK. Endometriosis and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Systematic Review and Meta-Analysis. Diagnostics (Basel). 2025 Sep 15;15(18):2332. doi: 10.3390/diagnostics15182332. PMID: 41008704. https://www.mdpi.com/2075-4418/15/18/2332 (Full text)

The health and economic burden on family caregivers of persons with me/cfs diagnosis: a register data study from Norway

Abstract:

Background: Myalgic encephalomyelitis is an illness that affects the labor capability and need for services among those affected. Interventions and services for comparable illnesses are either inaccessible or ineffective for this group. Partners and parents may take on the caregiver burden, affecting their labor capability and health.

Objective: This study tested how limited treatment and support options available to persons with myalgic encephalomyelitis is associated to work participation, health, and use of public transfers among partners and parents of those affected.

Methods: We used administrative data from Norwegian patient registries from 2009 to 2018 on the diagnostic code G93.3, matched with population register income and health data from Statistics Norway. The dataset made it possible to identify a sample of partners and parents of persons with the diagnosis. The data included a control group drawn from the general population. We used optimal pair matching to construct separate datasets for pairs of matched individuals from the control group and the group of G93.3 cases, their mothers, fathers, and male and female partners.

Results: Having a partner or child with the G93.3 diagnosis contributes to strengthening traditional gender roles. Female family members worked less, and male family members worked more. Whereas female family members more often ended up depending on public transfers, male family members did so less often. All caregiver groups experienced increased personal health problems.

Conclusions: When tailoring support for the patient group, welfare services should consider how especially female family caregivers may be adversely affected by insufficient or inadequate support.

Source: Kielland, A., Liu, J. & Anthun, K.S. The health and economic burden on family caregivers of persons with me/cfs diagnosis: a register data study from Norway. Discov Public Health 22, 567 (2025). https://doi.org/10.1186/s12982-025-00936-5 https://link.springer.com/article/10.1186/s12982-025-00936-5 (Full text)

Hormonal Fluctuations and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome in Women: The Role of Menstrual Cycle and Menopause

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a disabling multisystem disease, predominantly affecting women as compared to men and showing extreme symptom variability across reproductive life stages. The aim of this research was to determine the effects of hormonal changes, menopause status, and symptom severity in individuals with ME/CFS.

This was a prospective observational cohort study conducted at JPMC, Karachi from January 2024 to June 2025. Final recruitment was of 150 women with ME/CFS (90 were in the premenopausal, 30 in the perimenopausal and 30 in the postmenopausal strata). Baseline demographic and clinical profiling, laboratory hormonal assays (estradiol, progesterone, LH, FSH), symptom daily profiles and monthly activity data, and objective autonomic probe reflex testing (tilt-table studies) were obtained.

The findings revealed a clear hormonal gradient across the groups (ANOVA p < 0.001), with estradiol and progesterone levels becoming lower and gonadotropins higher with older reproductive age.

Symptom trajectories varied according to for premenopausal women: fatigue and pain peaked pre menstrually (CFQ p = 0.01, VAS p = 0.02) and cognitive impairment was lowest at ovulation (p = 0.04).

When comparing across menopause groups, symptom burden was greater in the perimenopausal and postmenopausal participants and the perimenopausal and postmenopausal participants had lower SF-36 quality-of-life component scores (physical functioning 0.01, mental health 0.04).

Tilt-table findings from the cohort suggest age-related differences in autonomic dysfunction with postmenopausal women more likely to exhibit orthostatic hypotension (36.7%) and premenopausal women more likely to express POTS (38.9%).

The correlation analysis revealed that low levels of estradiol and progesterone were significantly correlated with higher levels of fatigue and pain, whereas the opposite association was found for LH and FSH, the latter two being positively correlated with fatigue and orthostatic symptoms.

These findings provide the first quantifiable evidence for reproductive hormonal dynamics substantially modulating the clinical expression of ME/CFS in women and the need for hormone-sensitive management approaches.

Source: Mehak Khan, Sidra Anees, Muhammad Muthar Anees, Komal Khalid Chaudhry, Syeda Marium Rashid Zaidi, Vishan Das, Rimal Rashid. Hormonal Fluctuations and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome in Women: The Role of Menstrual Cycle and Menopause. The Research of Medical Science Review; Volume 3, Issue 8, 2025. ISSN: 3007-1208 & 3007-1216. https://medscireview.net/index.php/Journal/article/view/2032 (Full text available as PDF file)

Circulating Levels of SMPDL3B Define Metabolic Endophenotypes and Subclinical Kidney Alterations in Myalgic Encephalomyelitis

Abstract:

Myalgic Encephalomyelitis (ME) is a complex, multisystem disorder with poorly understood pathophysiological mechanisms. SMPDL3B, a membrane-associated protein expressed in renal podocytes, is essential for lipid raft integrity and glomerular barrier function. We hypothesize that reduced membrane-bound SMPDL3B may contribute to podocyte dysfunction and impaired renal physiology in ME. To investigate this, we quantified soluble SMPDL3B in plasma and urine as a surrogate marker of membrane-bound SMPDL3B status and assessed renal clearance and plasma metabolomic profiles.
In a cross-sectional study of 56 ME patients and 16 matched healthy controls, ME patients exhibited significantly lower urine-to-plasma ratios of soluble SMPDL3B and reduced renal clearance, suggesting podocyte-related abnormalities. Plasma metabolomics revealed dysregulation of metabolites associated with renal impairment, including succinic acid, benzoic acid, phenyllactic acid, 1,5-anhydroglucitol, histidine, and citrate.
In ME patients, plasma SMPDL3B levels inversely correlated with 1,5-anhydroglucitol concentrations and renal clearance. Multivariable modeling identified the urine-to-plasma SMPDL3B ratio as an independent predictor of clearance. Female ME patients showed more pronounced SMPDL3B alterations, reduced clearance, and greater symptom severity. Non-linear associations between soluble SMPDL3B and lipid species further suggest systemic metabolic remodeling.
These findings support soluble SMPDL3B as a potential non-invasive biomarker of renal-podocyte involvement in ME, highlighting sex-specific differences that may inform future therapeutic strategies.
Source: Rostami-Afshari B, Elremaly W, McGregor NR, Huang KJK, Armstrong CW, Franco A, Godbout C, Elbakry M, Abdelli R, Moreau A. Circulating Levels of SMPDL3B Define Metabolic Endophenotypes and Subclinical Kidney Alterations in Myalgic Encephalomyelitis. International Journal of Molecular Sciences. 2025; 26(18):8882. https://doi.org/10.3390/ijms26188882 https://www.mdpi.com/1422-0067/26/18/8882 (Full text)

Accelerated vascular ageing after COVID-19 infection: the CARTESIAN study

Abstract:

Background and Aims: Increasing evidence suggests that COVID-19 survivors experience long-term cardiovascular complications possibly through development of vascular damage. The study aimed to investigate whether accelerated vascular ageing occurs after COVID-19 infection, and if so, identify its determinants.
Methods: This prospective, multicentric, cohort study, included 34 centres in 16 countries worldwide, in 4 groups of participants—COVID-19-negative controls (ⅰ) and three groups of individuals with recent (6 ± 3 months) exposure to SARS-CoV-2: not hospitalized (ⅱ), hospitalized in general wards (ⅲ), and hospitalized in intensive care units (ⅳ). The main outcome was carotid-femoral pulse wave velocity (PWV), an established biomarker of large artery stiffness.
Results: 2390 individuals (age 50 ± 15 years, 49.2% women) were recruited. After adjustment for confounders, all COVID-19-positive groups showed higher PWV (+0.41, +0.37, and +0.40 m/s for groups 2–4, P < .001, P = .001 and P = .003) vs. controls [PWV 7.53 (7.09; 7.97) m/s adjusted mean (95% CI)]. In sex-stratified analyses, PWV differences were significant in women [PWV (+0.55, +0.60, and +1.09 m/s for groups 2–4, P < .001 for all)], but not in men. Among COVID-19 positive women, persistent symptoms were associated with higher PWV, regardless of disease severity and cardiovascular confounders [adjusted PWV 7.52 (95% CI 7.09; 7.96) vs. 7.13 (95% CI 6.67; 7.59) m/s, P < .001]. A stable or improved PWV after 12 months was found in the COVID+ groups, whereas a progression was observed in the COVID− group.
Conclusions: COVID-19 is associated with early vascular ageing in the long term, especially in women.

Source: Rosa Maria Bruno, Smriti Badhwar, Leila Abid, Mohsen Agharazii, Fabio Anastasio, Jeremy Bellien, Otto Burghuber, Luca Faconti, Jan Filipovsky, Lorenzo Ghiadoni, Cristina Giannattasio, Bernhard Hametner, Alun D Hughes, Ana Jeroncic, Ignatios Ikonomidis, Mai Tone Lonnebakken, Alessandro Maloberti, Christopher C Mayer, Maria Lorenza Muiesan, Anna Paini, Andrie Panayiotou, Chloe Park, Chakravarthi Rajkumar, Carlos Ramos Becerra, Bart Spronck, Dimitrios Terentes-Printzios, Yesim Tuncok, Thomas Weber, Pierre Boutouyrie, the CARTESIAN Investigators , Accelerated vascular ageing after COVID-19 infection: the CARTESIAN study, European Heart Journal, 2025;, ehaf430, https://doi.org/10.1093/eurheartj/ehaf430 https://academic.oup.com/eurheartj/advance-article/doi/10.1093/eurheartj/ehaf430/8236450 (Full text)