Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: the biology of a neglected disease

Abstract:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a chronic, debilitating disease characterised by a wide range of symptoms that severely impact all aspects of life. Despite its significant prevalence, ME/CFS remains one of the most understudied and misunderstood conditions in modern medicine. ME/CFS lacks standardised diagnostic criteria owing to variations in both inclusion and exclusion criteria across different diagnostic guidelines, and furthermore, there are currently no effective treatments available.

Moving beyond the traditional fragmented perspectives that have limited our understanding and management of the disease, our analysis of current information on ME/CFS represents a significant paradigm shift by synthesising the disease’s multifactorial origins into a cohesive model. We discuss how ME/CFS emerges from an intricate web of genetic vulnerabilities and environmental triggers, notably viral infections, leading to a complex series of pathological responses including immune dysregulation, chronic inflammation, gut dysbiosis, and metabolic disturbances.

This comprehensive model not only advances our understanding of ME/CFS’s pathophysiology but also opens new avenues for research and potential therapeutic strategies. By integrating these disparate elements, our work emphasises the necessity of a holistic approach to diagnosing, researching, and treating ME/CFS, urging the scientific community to reconsider the disease’s complexity and the multifaceted approach required for its study and management.

Source: Arron HE, Marsh BD, Kell DB, Khan MA, Jaeger BR, Pretorius E. Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: the biology of a neglected disease. Front Immunol. 2024 Jun 3;15:1386607. doi: 10.3389/fimmu.2024.1386607. PMID: 38887284; PMCID: PMC11180809. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11180809/ (Full text)

Systematic review of fatigue severity in ME/CFS patients: insights from randomized controlled trials

Abstract:

Background: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a debilitating illness medically unexplained, affecting approximately 1% of the global population. Due to the subjective complaint, assessing the exact severity of fatigue is a clinical challenge, thus, this study aimed to produce comprehensive features of fatigue severity in ME/CFS patients.

Methods: We systematically extracted the data for fatigue levels of participants in randomized controlled trials (RCTs) targeting ME/CFS from PubMed, Cochrane Library, Web of Science, and CINAHL throughout January 31, 2024. We normalized each different measurement to a maximum 100-point scale and performed a meta-analysis to assess fatigue severity by subgroups of age, fatigue domain, intervention, case definition, and assessment tool, respectively.

Results: Among the total of 497 relevant studies, 60 RCTs finally met our eligibility criteria, which included a total of 7088 ME/CFS patients (males 1815, females 4532, and no information 741). The fatigue severity of the whole 7,088 patients was 77.9 (95% CI 74.7-81.0), showing 77.7 (95% CI 74.3-81.0) from 54 RCTs in 6,706 adults and 79.6 (95% CI 69.8-89.3) from 6 RCTs in 382 adolescents. Regarding the domain of fatigue, ‘cognitive’ (74.2, 95% CI 65.4-83.0) and ‘physical’ fatigue (74.3, 95% CI 68.3-80.3) were a little higher than ‘mental’ fatigue (70.1, 95% CI 64.4-75.8). The ME/CFS participants for non-pharmacological intervention (79.1, 95% CI 75.2-83.0) showed a higher fatigue level than those for pharmacological intervention (75.5, 95% CI 70.0-81.0). The fatigue levels of ME/CFS patients varied according to diagnostic criteria and assessment tools adapted in RCTs, likely from 54.2 by ICC (International Consensus Criteria) to 83.6 by Canadian criteria and 54.2 by MFS (Mental Fatigue Scale) to 88.6 by CIS (Checklist Individual Strength), respectively.

Conclusions: This systematic review firstly produced comprehensive features of fatigue severity in patients with ME/CFS. Our data will provide insights for clinicians in diagnosis, therapeutic assessment, and patient management, as well as for researchers in fatigue-related investigations.

Source: Park JW, Park BJ, Lee JS, Lee EJ, Ahn YC, Son CG. Systematic review of fatigue severity in ME/CFS patients: insights from randomized controlled trials. J Transl Med. 2024 Jun 3;22(1):529. doi: 10.1186/s12967-024-05349-7. PMID: 38831460; PMCID: PMC11145935. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11145935/ (Full text)

The most severely ill patients with ME/CFS in Denmark

Abstract:

A subset of patients suffering from ME/CFS (Myalgic encephalomyelitis/chronic fatigue syndrome) are severely ill, bedridden, and dependent on personal care. This study aims to describe the medical and social conditions of the most severely ill patients with ME/CFS in Denmark and the situation of their caregivers.

Qualitative data were collected during 19 home visits to severely ill patients in Denmark. The patients interviewed were characterised by extremely low physical and mental functioning and longstanding illness. Relative to their dire condition, the participants received very little help from medical professionals and health services such as institutions and hospitals. There was an overall negative interaction with psychiatric interventions, and the relations between patients and the health system were generally characterised by mutual distrust. Social services were often dismissed, and obtaining the services was often described as more of a burden than a benefit.

In conclusion, the most severely ill patients with ME/CFS and their caregivers must be characterised as a systematically neglected patient group not comparable to any other similarly ill group.

Source: la Cour, P. (2024). The most severely ill patients with ME/CFS in Denmark. Cogent Public Health, 11(1). https://doi.org/10.1080/27707571.2024.2359958 https://www.tandfonline.com/doi/full/10.1080/27707571.2024.2359958 (Full text)

Psychological outcomes of COVID-19 survivors at sixth months after diagnose: the role of kynurenine pathway metabolites in depression, anxiety, and stress

Abstract:

Coronavirus disease 2019 (COVID-19) has resulted in long-term psychiatric symptoms because of the immunologic response to the virus itself as well as fundamental life changes related to the pandemic. This immune response leads to altered tryptophan (TRP)-kynurenine (KYN) pathway (TKP) metabolism, which plays an essential role in the pathophysiology of mental illnesses. We aimed to define TKP changes as a potential underlying mechanism of psychiatric disorders in post-COVID-19 patients.

We measured plasma levels of several TKP markers, including KYN, TRP, kynurenic acid (KYNA), 3-hydroxykynurenine (3-HK), and quinolinic acid (QUIN), as well as the TRP/KYN, KYNA/3-HK, and KYNA/QUIN ratios, in 90 post-COVID-19 patients (on the first day of hospitalization) and 59 healthy controls (on the first admission to the Check-Up Center). An online questionnaire that included the Depression, Anxiety and Stress Scale-21 (DASS-21) was used 6 months after the initial assessment in both groups.

A total of 32.2% of participants with COVID-19 showed depressive symptoms, 21.1% exhibited anxiety, and 33.3% had signs of stress at follow-up, while 6.6% of healthy controls exhibited depressive and anxiety symptoms and 18.6% had signs of stress. TRP and 3-HK were negative predictors of anxiety and stress, but KYN positively predicted anxiety and stress. Moreover, TRP negatively predicted depression, while KYNA/3-HK was a negative predictor of anxiety.

The correlation between depression, anxiety, and stress and TKP activation in COVID-19 could provide prospective biomarkers, especially the reduction in TRP and 3HK levels and the increase in KYN. Our results suggest that the alteration of TKP is not only a potential biomarker of viral infection-related long-term psychiatric disorders but also that the therapy targets future viral infections related to depression and anxiety.

Source: Kucukkarapinar M, Yay-Pence A, Yildiz Y, Buyukkoruk M, Yaz-Aydin G, Deveci-Bulut TS, Gulbahar O, Senol E, Candansayar S. Psychological outcomes of COVID-19 survivors at sixth months after diagnose: the role of kynurenine pathway metabolites in depression, anxiety, and stress. J Neural Transm (Vienna). 2022 Aug;129(8):1077-1089. doi: 10.1007/s00702-022-02525-1. Epub 2022 Jul 7. PMID: 35796878; PMCID: PMC9261222. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9261222/ (Full text)

Cerebral microstructural alterations in Post-COVID-condition are related to cognitive impairment, olfactory dysfunction and fatigue

Abstract:

After contracting COVID-19, a substantial number of individuals develop a Post-COVID-Condition, marked by neurologic symptoms such as cognitive deficits, olfactory dysfunction, and fatigue. Despite this, biomarkers and pathophysiological understandings of this condition remain limited. Employing magnetic resonance imaging, we conduct a comparative analysis of cerebral microstructure among patients with Post-COVID-Condition, healthy controls, and individuals that contracted COVID-19 without long-term symptoms.

We reveal widespread alterations in cerebral microstructure, attributed to a shift in volume from neuronal compartments to free fluid, associated with the severity of the initial infection. Correlating these alterations with cognition, olfaction, and fatigue unveils distinct affected networks, which are in close anatomical-functional relationship with the respective symptoms.

Source: Hosp JA, Reisert M, Dressing A, Götz V, Kellner E, Mast H, Arndt S, Waller CF, Wagner D, Rieg S, Urbach H, Weiller C, Schröter N, Rau A. Cerebral microstructural alterations in Post-COVID-condition are related to cognitive impairment, olfactory dysfunction and fatigue. Nat Commun. 2024 May 18;15(1):4256. doi: 10.1038/s41467-024-48651-0. PMID: 38762609; PMCID: PMC11102465. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11102465/ (Full text)

Long-COVID autonomic syndrome in working age and work ability impairment

Abstract:

Long-COVID19 has been recently associated with long-sick leave and unemployment. The autonomic nervous system functioning may be also affected by SARS-CoV-2, leading to a chronic autonomic syndrome. This latter remains widely unrecognized in clinical practice. In the present study, we assessed the occurrence of Long-COVID19 Autonomic Syndrome in a group of active workers as well as the relationships between their autonomic dysfunction and work ability.

This prospective observational study was conducted during the 2nd wave of the pandemic in Italy. Forty-five patients (53.6 ± 8.4 years; 32 M) hospitalized for COVID19, were consecutively enrolled at the time of their hospital discharge (T0) and followed-up for 6 months. Autonomic symptoms and work ability were assessed by COMPASS31 and Work Ability Index questionnaires at T0, one (T1), three and six (T6) months after hospital discharge and compared to those retrospectively collected for a period preceding SARS-CoV-2 infection. Clinical examination and standing test were also performed at T1 and T6.

One in three working-age people developed a new autonomic syndrome that was still evident 6 months after the acute infection resolution. This was associated with a significant reduction in the work ability. Recognition of Long-COVID19 Autonomic Syndrome may promote early intervention to facilitate return to work and prevent unemployment.

Source: Rinaldi L, Rigo S, Pani M, Bisoglio A, Khalaf K, Minonzio M, Shiffer D, Romeo MA, Verzeletti P, Ciccarelli M, Bordoni MG, Stranges S, Riboli E, Furlan R, Barbic F. Long-COVID autonomic syndrome in working age and work ability impairment. Sci Rep. 2024 May 23;14(1):11835. doi: 10.1038/s41598-024-61455-y. PMID: 38782998; PMCID: PMC11116376. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11116376/ (Full text)

The risks of autoimmune- and inflammatory post-acute COVID-19 conditions: a network cohort study in six European countries, the US, and Korea

ABSTRACT

Objectives We aimed to assess the risk of autoimmune- and inflammatory post-acute COVID-19 conditions.

Design Descriptive network cohort study.

Setting Electronic health records from UK and Dutch primary care, Norwegian linked health registry, hospital records of specialist centres in Spain, France, and Korea, and healthcare claims from Estonia and the US.

Participants We followed individuals between September 2020 and the latest available data from the day they fulfilled at least 365 days of prior observation (general population), additionally from day 91 after a SARS-Cov-2 negative test (comparator) or a COVID-19 record (exposed patients).

Main outcome measures We assessed postural orthostatic tachycardia syndrome (POTS) diagnoses/symptoms, myalgic encephalomyelitis / chronic fatigues syndrome (ME/CFS) diagnoses/symptoms, multi-inflammatory syndrome (MIS), and several autoimmune diseases. For contextualisation, we assessed any diabetes mellitus (DM).

Meta-analysed crude incidence rate ratios (IRR) of outcomes measures after COVID-19 versus negative testing yield the ratios of absolute risks. Furthermore, incidence rates (IR) of the outcomes in the general population describe the total disease burden.

Results We included 34’549’575 individuals of whom 2’521’812 had COVID-19, and 4’233’145 a first negative test. After COVID-19 compared to test negative patients, we observed IRRs of 1.24 (1.23-1.25), 1.22 (1.21-1.23), and 1.12 (1.04-1.21) for POTS symptoms, ME/CFS symptoms and diagnoses, respectively. In contrast, autoimmune diseases and DM did not yield higher rates after COVID-19. In individual general database populations, IRs of POTS and ME/CFS diagnoses were 17-1’477/100’000 person-years (pys) and 2-473/100’000 pys, respectively. IRs of MIS were lowest with IRs 0.4-16/100’000 pys, those of DM as a benchmark 8-86/100’000 pys. IRs largely depended on the care setting.

Conclusion In our unmatched comparison, we observed that, following COVID-19, POTS and ME/CFS yielded higher rates than after negative testing. In absolute terms, we observed POTS and ME/CFS diagnoses to have a similar disease burden as DM.

WHAT IS ALREADY KNOWN ON THIS TOPIC

  • Observational research suggested positive associations between COVID-19 and so called post-acute COVID-19 conditions, whose spectrum is yet to be established

  • Basic research suggested pathways that link COVID-19 with autoimmune- and inflammatory diseases such as postural orthostatic tachycardia syndrome (POTS), myalgic encephalomyelitis / chronic fatigues syndrome (ME/CFS), multiple inflammatory syndrome (MIS), and autoimmune diseases

WHAT THIS STUDY ADDS

  • After COVID-19, the rates of POTS symptoms and ME/CFS symptoms/diagnoses was higher than those after negative testing

  • After COVID-19 versus negative testing, rates of ME/CFS diagnoses were increased in the working age group and rates of symptoms of POTS and ME/CFS were increased in children and elderly

  • Disease burdens of POTS and ME/CFS diagnoses in the general population were higher among women than among men and overall similar to that of diabetes mellitus

Source: Theresa Burkard, Kim López-Güell, Martí Català, Edward Burn, Antonella Delmestri, Sara Khalid, Annika M Joedicke, Daniel Dedman, Jessie O Oyinlola, Alicia Abellan, Laura Pérez-Crespo, Núria Mercadé-Besora, Talita Duarte-Salles, Daniel Prieto-Alhambra, Johnmary T Arinze, Mees Mosseveld, Raivo Kolde, Jaime Meléndez-Cardiel, Raúl López-Blasco, Álvaro Martínez, Bernardo Valdivieso, Dominique Delseny, Gregoire Mercier, Chungsoo Kim, Ji-woo Kim, Kristin Kostka, Juan Manuel Ramírez-Anguita, Miguel A Mayer, Nhung TH Trinh, Hedvig ME Nordeng, Roger Paredes, Anneli Uusküla, Akihiko Nishimura, Cora Loste, Lourdes Mateu, Junqing Xie. The risks of autoimmune- and inflammatory post-acute COVID-19 conditions: a network cohort study in six European countries, the US, and Korea. medRxiv 2024.05.15.24307344; doi: https://doi.org/10.1101/2024.05.15.24307344 https://www.medrxiv.org/content/10.1101/2024.05.15.24307344v1.full-text (Full text)

Impact of inflammatory response in the acute phase of COVID-19 on predicting objective and subjective post-COVID fatigue

Abstract:

The biological predictors of objective and subjective fatigue in individuals with post-COVID syndrome remains unclear. This study aims to ascertain the predictive significance of the immune response measured during the acute phase of SARS-CoV-2 infection on various dimensions of fatigue 6–9 months post-infection.

We examined the association between immune markers obtained from the serum of 54 patients (mean age: 58.69 ± 10.90; female: 31%) and objective and subjective chronic fatigue using general linear mixed models. Level of IL-1RA, IFNγ and TNFα in plasma and the percentage of monocytes measured in the acute phase of COVID-19 predicted physical and total fatigue.

Moreover, the higher the concentration of TNFα (r=-0.40 ; p = .019) in the acute phase, the greater the lack of awareness of cognitive fatigue 6–9 months post-infection. These findings shed light on the relationship between acute inflammatory response and the persistence of both objective and subjective fatigue.

Source: Julie Péron, Anthony Nuber-Champier, Gautier Breville et al. Impact of inflammatory response in the acute phase of COVID-19 on predicting objective and subjective post-COVID fatigue, 28 May 2024, PREPRINT (Version 1) available at Research Square [https://doi.org/10.21203/rs.3.rs-4374986/v1] https://www.researchsquare.com/article/rs-4374986/v1 (Full text)

Learning points about myalgic encephalitis/chronic fatigue syndrome

Abstract:

This essay examines the complex landscape of myalgic encephalitis, commonly known as chronic fatigue syndrome, highlighting its chronic and multisystemic nature with elusive causative factors. It discusses clinical challenges in diagnosis and management, emphasising the importance of increased education and awareness among healthcare professionals. The role of empathic, person-centred care in improving patient outcomes is underscored, urging for a paradigm shift towards understanding and addressing the profound impact of myalgic encephalitis/chronic fatigue syndrome on patients’ lives.

Source: Wahi-Singh B. Learning points about myalgic encephalitis/chronic fatigue syndrome: Bridging the gap between research, clinical practice and awareness. J R Coll Physicians Edinb. 2024 May 27:14782715241257968. doi: 10.1177/14782715241257968. Epub ahead of print. PMID: 38798182. https://journals.sagepub.com/doi/10.1177/14782715241257968 (Full text)

Longitudinal Progression of Patients with Long COVID Treated in a Post-COVID Clinic: A Cross-Sectional Survey

Abstract:

Background: In addition to the morbidity and mortality associated with acute infection, COVID-19 has been associated with persistent symptoms (>30 days), often referred to as Long COVID (LC). LC symptoms often cluster into phenotypes, resembling conditions such as fibromyalgia, postural orthostatic tachycardiac syndrome (POTS), and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). LC clinics have been established to best address the needs of LC patients and continuity of care. We developed a cross-sectional survey to assess treatment response through our LC Clinic (LCC).

Methods: A 25-question survey (1-10 Likert scale) was expert- and content-validated by LCC clinicians, patients, and patient advocates. The survey assessed LC symptoms and the helpfulness of different interventions, including medications and supplements. A total of 852 LCC patients were asked to complete the survey, with 536 (62.9%) responding.

Results: The mean time from associated COVID-19 infection to survey completion was 23.2 ± 6.4 months. The mean age of responders was 52.3 ± 14.1 (63% females). Self-reported symptoms were all significantly improved (P < .001) from the initial visit to the LCC (baseline) to the time of the follow-up survey. However, only 4.5% (24/536) of patients rated all symptoms low (1-2) at the time of the survey, indicating low levels of full recovery in our cohort. The patients rated numerous interventions as being helpful, including low-dose naltrexone (45/77; 58%), vagal nerve stimulation (18/34; 53%), and fisetin (28/44; 64%).

Conclusions: Patients report general improvements in symptoms following the initial LCC visit, but complete recovery rates remain low at 23.2 ± 6.4 months.

Source: Hurt RT, Yadav S, Schroeder DR, Croghan IT, Mueller MR, Grach SL, Aakre CA, Gilman EA, Stephenson CR, Overgaard J, Collins NM, Lawson DK, Thompson AM, Natividad LT, Mohamed Elfadil O, Ganesh R. Longitudinal Progression of Patients with Long COVID Treated in a Post-COVID Clinic: A Cross-Sectional Survey. J Prim Care Community Health. 2024 Jan-Dec;15:21501319241258671. doi: 10.1177/21501319241258671. PMID: 38813984. https://journals.sagepub.com/doi/10.1177/21501319241258671 (Full text)