Welcome to the 112th edition of Emerge Australia’s Research Digest. This month, we look at the latest research on ME/CFS and post-COVID conditions. The studies explore how common these conditions are, the symptoms they share, and how they affect the body, including metabolism and heart health. They also look at the possibility of personalised treatments. From the connection between ME/CFS and COVID-19 to the role of taurine in post-COVID conditions, this research shows the need for teamwork across different areas of healthcare to better support people with these conditions.
Contributing Digesters: Jyothsna, Solène, Shan and Sarah.
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Myalgic encephalomyelitis/chronic fatigue syndrome after SARS-CoV-2 infection
Authors: Unger ER, Lin JMS, Wisk LE, Yu H, L’Hommedieu M, Lavretsky H… Elmore JE (University of California, USA)
Publication: JAMA Network Open
Link: https://jamanetwork.com/journals/jamanetworkopen/article-abstract/2821459
The COVID-19 pandemic increased awareness of post-acute infection syndromes (PAISs), providing a unique opportunity to study ME/CFS following a specific infection. The aim of this study, which led to the U.S.-based Innovative Support for Patients with SARS-CoV-2 Infections Registry (INSPIRE) study, was to examine the prevalence of ME/CFS after SARS-CoV-2 infection, changes in ME/CFS symptoms after 12 months, and the relationship between ME/CFS symptoms and SARS-CoV-2 test during acute illness.
This prospective cohort study included 4,738 participants aged 18 and older who experienced COVID-19-like illness between December 11, 2020, and August 29, 2022, across eight U.S. study sites. The average participant age was 37.8 years, with 68.1% identifying as female. Racial demographics showed 66.1% were White, 13.3% Asian/Pacific Islander, 10.8% Black, and 9.7% multiracial, while 14.6% identified as Hispanic or Latino.
The study tracked ME/CFS symptoms in both COVID-19-positive and COVID-19-negative groups, finding no significant differences in symptom prevalence over the 12-month follow-up. At 3 months, 3.4% of the COVID-19-positive participants and 3.7% of the COVID-19-negative participants met ME/CFS criteria, with common symptoms including fatigue, unrefreshing sleep, and post-exertional malaise. Symptom prevalence ranged from 2.8% to 4.5% throughout the study.
The authors conclude that COVID-19 does not appear more likely than other infections to lead to ME/CFS, suggesting that various acute infections may result in chronic symptoms. The authors highlight the study’s strengths, such as its large, diverse sample and comprehensive symptom tracking. They also acknowledge limitations, including potential misclassification, recall bias, and underreported COVID-19 cases. Despite these, the authors propose that findings support the need for clinical management strategies for ME/CFS, with COVID-19-related ME/CFS potentially managed similarly to other PAISs.
Illness presentation and quality of life in myalgic encephalomyelitis/chronic fatigue syndrome and post COVID‐19 condition: a pilot Australian cross‐sectional study
Authors: Weigel B, Eaton-Fitch N, Thapaliya K, Marshall-Gradisnik S. (Griffith University, Australia)
Publication: Quality of Life Research
Link: https://doi.org/10.1007/s11136-024-03710-3
Post COVID-19 Condition (PCC) has many overlapping symptoms with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). This study’s goals were (1) to compare the symptoms of PCC with ME/CFS to improve PCC diagnostic criteria and (2) to compare health outcomes between patients and healthy people (controls) to highlight these illnesses’ burdens.
In total, 146 participants (mostly women) were involved in this study, including 61 with ME/CFS, 31 with PCC, and 54 with no chronic conditions (controls). All participants completed the 36-Item Short-Form Health Survey version 2 (SF-36v2), the World Health Organization Disability Assessment Schedule version 2.0 (WHODAS 2.0), the Hospital Anxiety and Depression Scale (HADS), and the Modified Fatigue Impact Scale (MFIS) to compare the quality of life and functional capacity of ME/CFS and PCC participants with controls.
Researchers identified many similarities between both diseases. Essential symptoms in ME/CFS, such as post-exertional malaise, neurocognitive impairment, and sleep disturbances are shared with PCC. These results suggest that post-exertional malaise, as a critical component of PCC, should be included in diagnosis and care provision. Differences between both diseases involved memory loss, unrefreshed sleep, muscle weakness, and lymphadenopathy, all significantly more prevalent in ME/CFS than in PCC.
Compared with controls, ME/CFS and PCC participants experienced a noteworthy reduction in their capacity to perform daily activities. SF-36v2 Role Physical, SF-36v2 Vitality scores, WHODAS 2.0 Life Activities 1, WHODAS 2.0 Participation, and MFIS Physical scores were significantly lower in ME/CFS and PCC than in controls. SF-36v2 Role Emotional, SF-36v2 Mental Health and HADS Depression subscales scores of participants with ME/CFS and PCC participants were significantly different to controls, highlighting the mental health impacts of these conditions. There were no significant differences between the groups on the HADS Anxiety subscale.
Comprehensive longitudinal data with a larger sample size is needed to fully understand the illness burdens of ME/CFS and PCC. However, this study already highlights the necessity of multidisciplinary healthcare, disability and social support for ME/CFS and PCC patients in Australia.
Plasma taurine level is linked to symptom burden and clinical outcomes in post-COVID condition
Authors: Khoramjoo M, Wang K, Srinivasan K, Gheblawi M, Mandal R, Rousseau S … Oudit GY (University of Alberta, Canada)
Publication: PLoS ONE
Link: https://doi.org/10.1371/journal.pone.0304522
SARS-CoV-2 is known to dysregulate a variety of metabolic pathways, including the metabolism of taurine. Taurine is a semi-essential amino acid that suppresses inflammation, slows cellular aging, acts as an antioxidant, and supports metabolic, cardiovascular, and neurocognitive function. The study aimed to examine the link between plasma taurine levels and the symptoms and clinical outcomes of patients with post-COVID condition (PCC).
Between October 2020 and June 2021, the COVID-19 Surveillance Collaboration Study recruited 117 patients (56.4% male; 43.6% female) upon admission to the hospital with a positive PCR test for SARS-CoV-2. Seventy-three per cent of the COVID-19 patients had the original SARS-CoV-2 variant. The study also included 28 age and sex-matched healthy controls (HC). Blood samples were taken upon enrolment and six months later to measure cytokines, peptides, and metabolites. Electronic medical records and a symptom questionnaire were used to track symptom progression from acute illness to the convalescent phase at six months post-infection, including whether patients experienced an adverse clinical event after hospital discharge.
Taurine was identified as one of the top upregulated metabolites in PCC. It was significantly elevated in acute infection compared to HC and elevated further six months post-infection. Plasma levels of taurine were positively correlated with tryptophan and serotonin, but negatively correlated with inflammatory markers and gut dysbiosis markers. Taurine levels were also strongly negatively correlated with quinolinic acid, a neurotoxic byproduct of tryptophan. Additionally, PCC severity and symptom burden were negatively correlated with taurine levels. A decrease in taurine levels was also associated with an increased risk of an adverse clinical event.
This study demonstrates the link between plasma taurine levels and PCC symptoms, adverse clinical outcomes and metabolic alterations, which the authors believe suggests a protective role of taurine against PCC. They hypothesise that neglecting to upregulate taurine during SARS-CoV-2 infection may predispose patients to experience worse outcomes during the acute and convalescence phases. The authors also hypothesise that reduced taurine levels may explain some of the similar symptoms in ME/CFS and PCC. The authors recommend large-scale clinical trials of taurine supplementation as a treatment for PCC.
Sleep and circadian rhythm alterations in myalgic encephalomyelitis/chronic fatigue syndrome and post-COVID fatigue syndrome and its association with cardiovascular risk factors: A prospective cohort study
Authors: Zerón-Rugerio MF, Zaragozá MC, Domingo JC, Sanmartín-Sentañes R, Alegre-Martin J, Castro-Marrero J & Cambras T (University of Barcelona, Spain).
Publication: Chronobiology International
Link: https://www.tandfonline.com/doi/full/10.1080/07420528.2024.2380020
ME/CFS may present with a variety of symptoms, including disrupted sleep patterns and altered circadian rhythms, which are common symptoms in both ME/CFS and post-COVID ME/CFS. This study sought to investigate sleep and circadian rhythm alterations in ME/CFS, and their association with endothelial dysfunction and cardiovascular health. Sex-based variations in sleep and circadian rhythms were also investigated.
Thirty-one ME/CFS patients (International Consensus Criteria), 23 individuals with long-COVID (post-COVID ME/CFS), and 31 healthy controls were included in this study. Participants were consecutively recruited from the Vall d’Hebron University Hospital in Spain. Actigraphy data (measuring skin temperature, motor activity and light intensity) was collected over one week via a wrist-worn device, and self-reported questionnaires were also completed. Blood pressure and heart rate were also measured, and blood samples were collected from participants.
Both patient groups showed lower activity levels and worse sleep quality than the healthy control group. Worse lipid profiles were also seen in the patient groups, and this was associated with disturbances to the circadian temperature rhythm. Sex-based differences in sleep disturbances were observed in healthy controls, but not in either patient group. No significant differences were observed in endothelial dysfunction biomarkers or sleep and circadian variables between the two patient groups.
The authors conclude that these findings suggest lipid profiles in ME/CFS may contribute to the disrupted circadian rhythms and sleep patterns that are frequently reported in this condition, with endothelial dysfunction likely playing a key role. They also propose that these findings highlight the complex relationship between sleep, circadian rhythms and cardiovascular health in ME/CFS. Further investigation of plasma lipids may assist in developing personalised treatments for ME/CFS patients.
