ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

1021–1040 of 6,187 studies

E2 ModerateCohortPEM unclearCase-Control

Interpreting hand grip strength in hospital employees with post-COVID syndrome compared to non-infected controls: a case-control study.

Tack, Matthias, Gruber, Rosalie, Betting, Leia et al.·Scientific reports·2026

This small study compared hand grip strength in 19 hospital workers with post-COVID syndrome (including 7 who met ME/CFS criteria) to 23 healthy controls. Researchers found that grip strength tended to be lower in the post-COVID group, particularly when tested a second time after a 60-minute break, which might suggest difficulty recovering after repeated effort. However, these are preliminary findings from a small group, and the authors note that grip strength alone is not reliable enough to diagnose post-COVID syndrome.

DiagnosticsPost-Exertional Malaise

E2 ModerateCohortPEM unclearCase-Control

Sleep in myalgic encephalomyelitis/chronic fatigue syndrome shows marked night-to-night fluctuation under free-living conditions-results from a matched case-control study.

Saurel, Maïtena, Fornasieri, Isabelle, Del Sordo, Giovanna C et al.·Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine·2026

This study observed that people with ME/CFS who wore sleep-tracking wristbands for a week showed poorer sleep quality and more night-to-night variability in how well they slept compared to matched controls—even though they spent more time in bed. The sleep pattern was unstable from night to night, which may be an important feature of ME/CFS sleep problems that laboratory studies (typically 1–2 nights) do not capture.

SleepDiagnostics

E2 ModerateCohortPEM unclearCase-Control

Phosphoproteomic analysis reveals differential associations between liver-spleen disharmony and qi-blood deficiency syndromes in chronic fatigue syndrome.

Zhang, Jiabao, Tian, Ying, Sun, Guanghan et al.·Journal of translational medicine·2026

Researchers compared blood protein markers in 30 people—10 with ME/CFS showing Traditional Chinese Medicine (TCM) 'Liver-Spleen Disharmony' patterns, 10 with 'Qi-Blood Deficiency' patterns, and 10 healthy controls—using advanced protein analysis. They observed different patterns of phosphorylated proteins (chemical modifications on proteins) between the two ME/CFS groups and healthy controls, suggesting that TCM pattern categories may have distinct molecular signatures. However, this is an early exploratory study with a small sample size, and these findings have not yet been replicated.

BiomarkersDiagnostics

E2 ModerateCohortPEM unclearCross-Sectional

Plasma Extracellular Vesicle Surface Marker Profiling Reveals Immune Cell-Associated Mitochondrial Membrane Potential Alterations in Long COVID and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Ikeda, Gentaro, Koike-Ieki, Mariko, Inoue, Hiroyuki et al.·Open forum infectious diseases·2026

Researchers analyzed tiny cell particles called extracellular vesicles in blood samples from people with Long COVID, ME/CFS, and healthy controls. They observed that both Long COVID and ME/CFS groups had elevated levels of certain immune cell-derived particles and alterations in mitochondrial (energy-producing) markers within B cells and other immune cells, though the findings were not identical between groups. These preliminary results suggest there may be shared immune and metabolic changes in these conditions, but the meaning of these changes for patient health remains unclear and needs further study.

BiomarkersEnergy MetabolismImmune SystemLong COVID Overlap

E2 ModerateCohortPEM not requiredLongitudinal

Long COVID longitudinal symptoms burden clusters within a national community-based cohort.

Shen, Yanhan, Shahn, Zach, Robertson, McKaylee M et al.·BMC infectious diseases·2026

This study followed over 500 people with long COVID for up to a year, tracking their symptoms over time. Researchers identified three groups based on symptom burden: one with persistent severe symptoms (including fatigue, brain fog, post-exertional malaise, and pain), one with moderate symptoms that improved, and one with minimal symptoms. The findings are preliminary and based on self-reported data, so the stability and generalisability of these groups to other long COVID populations remain to be confirmed.

Pain and SensitizationSleepAutonomic Nervous SystemCognitive Impairment

E2 ModerateCohortPEM not requiredObservational

Shared genetic risk between functional somatic syndromes, internalizing disorders, and immune-mediated diseases: a twin-sibling study.

Steen, Olivier D, Ohlsson, Henrik, van Ockenburg, Sonja L et al.·Brain, behavior, and immunity·2026

A large Swedish study examined whether functional somatic syndromes (including ME/CFS, fibromyalgia, and IBS) and depression/anxiety share genetic risk factors with immune-mediated diseases. Researchers observed that fibromyalgia showed the strongest shared genetic risk with immune diseases, while ME/CFS showed more modest genetic overlap. The findings are preliminary and do not explain why these conditions cluster together, only that genetic factors may contribute to some shared risk.

BiomarkersImmune System

E2 ModerateCohortPEM not requiredCross-Sectional

Subclinical Hypercoagulable Viscoelastic Characteristics Associated with Post-Acute Sequelae of SARS-CoV2 Physical Symptoms in COVID-19 ALI/ARDS Survivors.

Jones, Ansley E, Mira-Sanchez, Margarita, Khan, Zain et al.·Journal of intensive care medicine·2026

This study examined blood clotting patterns in 93 people who survived severe COVID-19 requiring hospitalization, testing them 15 months after discharge. Researchers observed that those with lingering post-COVID symptoms—particularly fatigue and post-exertional malaise (worsening after activity)—showed altered clotting characteristics on specialized blood tests, specifically higher fibrinogen levels. However, this is a single cross-sectional study and does not establish whether these clotting changes cause the symptoms or are simply associated with them.

BiomarkersLong COVID Overlap

E2 ModerateCohortPEM unclearCross-Sectional

Comprehensive Immunophenotyping of Monocytes and Dendritic Cells Suggests Distinct Pathophysiology in Chronic Fatigue Syndrome and Long COVID.

Petrov, Steliyan, Bozhkova, Martina, Ivanovska, Mariya et al.·International journal of molecular sciences·2026

Researchers compared immune cell patterns in 103 people with ME/CFS, 63 with long COVID, and 41 healthy controls using blood tests. They observed that ME/CFS and long COVID show different patterns of immune cell activity—long COVID appeared to show persistent immune activation, while ME/CFS appeared associated with reduced immune signalling. These are early findings from one study and do not yet tell us what causes either condition or how to treat it.

BiomarkersDiagnosticsImmune SystemLong COVID Overlap

E2 ModerateCohortPEM unclearCross-Sectional

Central noradrenergic deficiency in post-infectious chronic fatigue: neurobehavioral correlates.

Aregawi, Lillian, Walitt, Brian, Sullivan, Patti et al.·Brain communications·2026

Researchers measured levels of norepinephrine (a brain chemical) in cerebrospinal fluid from people with ME/CFS, Long COVID, and Parkinson's disease, comparing them to healthy volunteers. They observed that norepinephrine pathway activity was lower in all three patient groups, and in Long COVID patients with post-exertional malaise, this reduction was particularly pronounced. This is one study in a small sample, and it remains unclear whether these findings fully explain fatigue and brain fog or apply directly to ME/CFS.

BiomarkersCognitive ImpairmentLong COVID OverlapPost-Exertional Malaise

E2 ModerateCohortPEM unclearObservational

Cardiopulmonary exercise test results do not change over two sequential days in patients with chronic fatigue syndrome.

Mancini, Donna M, Cook, Dane B, Brunjes, Danielle L et al.·Frontiers in physiology·2026

Researchers asked whether doing two exercise tests on consecutive days could reliably detect post-exertional malaise (PEM) in ME/CFS patients. They found that oxygen consumption and other key exercise measures did not change between Day 1 and Day 2 in either ME/CFS patients or healthy controls. However, ME/CFS patients reported much greater fatigue during exercise and had lower maximum heart rates. One study's findings do not establish whether this two-day test method is truly useful for measuring PEM in clinical practice.

DiagnosticsPost-Exertional Malaise

E2 ModerateCohortPEM unclearObservational

Hyperbaric oxygen therapy improves clinical symptoms and functional capacity and modulates thalamic connectivity in ME/CFS: a prospective cohort study.

Kim, Laura, Cammà, Guido, Peters, Claudia Kedor et al.·Journal of translational medicine·2026

This observational study of 30 ME/CFS patients reported improvements in physical functioning, fatigue, and pain after 40 sessions of hyperbaric oxygen therapy (HBOT), with associated changes in brain connectivity patterns. However, this is a single-group study without a control arm receiving a sham or alternative treatment, so we cannot yet determine whether observed improvements were due to HBOT itself or other factors such as expectancy or natural variation.

NeuroinflammationInterventionsAutonomic Nervous SystemCognitive Impairment

E2 ModerateCohortPEM unclearCross-Sectional

Raman Spectroscopy Combined with Machine Learning Reveals Myalgic Encephalomyelitis-Associated Biomolecular Signatures at Rest and After Standardized Stress.

Heidarifard, Maryam, Moezzi, Atefeh, Dallaire, Frédérick et al.·International journal of molecular sciences·2026

Researchers used a laboratory technique called Raman spectroscopy combined with computer learning to identify chemical signatures in blood plasma that are associated with ME/CFS. They collected blood samples from 115 ME/CFS patients and 45 healthy controls both at rest and 90 minutes after a standardized stress test, and found the method could distinguish between the two groups with moderate-to-good accuracy (79–84%). However, this is an early-stage study and much more work is needed before such a test could be used in clinical practice.

BiomarkersDiagnosticsPost-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

Irisin Signaling Resistance in Myalgic Encephalomyelitis: A Proposed Mechanistic Framework for Post-Exertional Malaise Involving the TSP-1-HSP90α-αvβ5 Axis.

Souma, Bernard, Elremaly, Wesam, Akoume, Marie-Yvonne et al.·International journal of molecular sciences·2026

Researchers compared blood levels of two proteins—irisin and thrombospondin-1 (TSP-1)—in 92 ME/CFS patients and 44 healthy controls, measuring them before and after a physical stress test. They observed that ME/CFS patients had lower baseline irisin levels and a weaker response to the stress challenge, while those with more severe symptoms showed elevated levels of both proteins. The study proposes that TSP-1 may interfere with irisin's normal signaling, potentially contributing to energy problems in ME/CFS, but these findings are preliminary and require validation in larger studies.

BiomarkersEnergy MetabolismPost-Exertional Malaise

E2 ModerateCohortPEM unclearLongitudinal

Two-timepoint multidomain follow-up of post-COVID condition and ME/CFS: overlapping autonomic, small-fiber, and cognitive changes.

Azcue, N, Barranco, C, Tijero-Merino, B et al.·Journal of translational medicine·2026

Researchers compared 21 people with post-COVID condition and 17 people with ME/CFS over about 2.5 years, measuring nerve function, autonomic symptoms, and cognitive performance. They observed that both groups showed similar patterns of changes over time—including worsening processing speed and cold sensation sensitivity, but improving heat sensation thresholds and verbal memory. While the two conditions appeared increasingly alike on follow-up testing, the study does not establish whether they are truly the same disease or simply share overlapping symptoms.

Pain and SensitizationAutonomic Nervous SystemDiagnosticsCognitive Impairment

E2 ModerateCohortPEM not requiredCross-Sectional

Symptom profiles and health-related quality of life in Korean adults with post-acute sequelae of SARS-CoV-2 infection (PASC): A latent profile analysis.

Kim, Su-Jin, Kim, Jinhee·PloS one·2026

This study examined symptom patterns in 629 Korean adults with long COVID (persistent symptoms ≥12 weeks after COVID-19). Researchers identified four distinct groups: people with few symptoms, moderate multi-body symptoms, fatigue and post-exertional malaise-dominant symptoms, and severe multi-body symptoms. Quality of life decreased substantially as symptom burden increased. The findings are observational and reflect one population; whether they apply to ME/CFS remains unclear.

DiagnosticsCognitive ImpairmentPost-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

Elevated serum levels of interleukin-11 and matrix metalloproteinase-9 in myalgic encephalomyelitis/chronic fatigue syndrome.

Chinnappan, Baskaran, Kempuraj, Duraisamy, Aenlle, Kristina K et al.·Frontiers in immunology·2026

Researchers measured two immune proteins (IL-11 and MMP-9) in the blood of 40 ME/CFS patients and compared them to healthy controls, finding higher levels in the ME/CFS group. In the laboratory, they also showed that immune cells called mast cells release MMP-9 when exposed to a protein from Epstein-Barr virus. These are preliminary observations in one study that suggest these proteins may be associated with ME/CFS, but this does not yet establish their role in the disease.

NeuroinflammationBiomarkersImmune System

E2 ModerateCohortPEM unclearCross-Sectional

Comparative Gut Microbiome Alterations in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Long COVID-19 Syndrome.

Donchev, Deyan, Nikolova, Ralitsa, Vaseva, Katya et al.·Biomedicines·2026

Researchers compared gut bacteria in people with ME/CFS, long COVID, and healthy controls using stool samples. They observed that both ME/CFS and long COVID showed similar patterns of bacterial changes—including more of a bacterium called Sutterella and less of others—compared to healthy people, though the two conditions were not identical. The strongest links between bacterial patterns and symptoms were observed in fatigue and physical symptoms, though this is one study and findings require confirmation in larger follow-up research.

BiomarkersGut MicrobiomeEnergy MetabolismLong COVID Overlap

E2 ModerateCohortPEM unclearCross-Sectional

Symptom, Functional, and Work Participation Profiles Among Racialized Canadians with Pre-Existing Mental Health Challenges and Long COVID: A Cross-Sectional Study.

Shahzad, Maryam, Siddiqui, Sana, Lau, Chloe et al.·Healthcare (Basel, Switzerland)·2026

This study observed symptom burden, functional impairment, and mental health outcomes in 51 Canadian adults with long COVID who also identified as racialized and had pre-existing mental health conditions. Participants reported moderate overall symptoms, notable fatigue and post-exertional malaise, cognitive difficulties, and mild-to-moderate anxiety and depression, alongside moderate functional limitations in work, social, and daily activities. However, this is a small, self-selected group, and the findings may not generalise to all long COVID patients.

Cognitive ImpairmentLong COVID OverlapPost-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

Exploring differences in protein cargo of extracellular vesicles from ME/CFS patient plasma compared to healthy controls.

Rydland, Anne, Yran, Elena Støvring, Nyman, Tuula A et al.·Biochemistry and biophysics reports·2026

Researchers compared tiny particles called extracellular vesicles (EVs) in the blood of 49 ME/CFS patients and 50 healthy controls. They found that ME/CFS patients had higher concentrations of these particles, and 11 proteins inside them were observed at different levels in ME/CFS compared to controls—though these differences did not remain statistically significant after accounting for multiple comparisons. The study is exploratory and the authors note that further investigation is needed to understand whether these EV changes are relevant to ME/CFS.

BiomarkersImmune System

E2 ModerateCohortPEM unclearCross-Sectional

Association between light exposure patterns and multidimensional health outcomes in individuals with myalgic encephalomyelitis/chronic fatigue syndrome: findings from an observational cross-sectional cohort study.

Cambras, Trinitat, Domingo, Joan Carles, Sanmartín-Sentañes, Ramon et al.·Journal of translational medicine·2026

This study observed patterns of light exposure in 100 ME/CFS patients and 56 healthy controls over one week, using wrist-worn devices to track light, activity, and body temperature. Researchers found that ME/CFS patients with more stable daytime light exposure reported lower fatigue, better sleep, and higher quality of life compared to those with irregular or nighttime-dominant light patterns; these associations were not observed in healthy controls. The findings suggest light exposure patterns may be worth studying as a potentially modifiable lifestyle factor, though the study cannot prove that changing light exposure would improve symptoms.

BiomarkersInterventionsSleepAutonomic Nervous System

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Evidence Atlas

Evidence browser

Interpreting hand grip strength in hospital employees with post-COVID syndrome compared to non-infected controls: a case-control study.

Sleep in myalgic encephalomyelitis/chronic fatigue syndrome shows marked night-to-night fluctuation under free-living conditions-results from a matched case-control study.

Phosphoproteomic analysis reveals differential associations between liver-spleen disharmony and qi-blood deficiency syndromes in chronic fatigue syndrome.

Plasma Extracellular Vesicle Surface Marker Profiling Reveals Immune Cell-Associated Mitochondrial Membrane Potential Alterations in Long COVID and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Long COVID longitudinal symptoms burden clusters within a national community-based cohort.

Shared genetic risk between functional somatic syndromes, internalizing disorders, and immune-mediated diseases: a twin-sibling study.

Subclinical Hypercoagulable Viscoelastic Characteristics Associated with Post-Acute Sequelae of SARS-CoV2 Physical Symptoms in COVID-19 ALI/ARDS Survivors.

Comprehensive Immunophenotyping of Monocytes and Dendritic Cells Suggests Distinct Pathophysiology in Chronic Fatigue Syndrome and Long COVID.

Central noradrenergic deficiency in post-infectious chronic fatigue: neurobehavioral correlates.

Cardiopulmonary exercise test results do not change over two sequential days in patients with chronic fatigue syndrome.

Hyperbaric oxygen therapy improves clinical symptoms and functional capacity and modulates thalamic connectivity in ME/CFS: a prospective cohort study.

Raman Spectroscopy Combined with Machine Learning Reveals Myalgic Encephalomyelitis-Associated Biomolecular Signatures at Rest and After Standardized Stress.

Irisin Signaling Resistance in Myalgic Encephalomyelitis: A Proposed Mechanistic Framework for Post-Exertional Malaise Involving the TSP-1-HSP90α-αvβ5 Axis.

Two-timepoint multidomain follow-up of post-COVID condition and ME/CFS: overlapping autonomic, small-fiber, and cognitive changes.

Symptom profiles and health-related quality of life in Korean adults with post-acute sequelae of SARS-CoV-2 infection (PASC): A latent profile analysis.

Elevated serum levels of interleukin-11 and matrix metalloproteinase-9 in myalgic encephalomyelitis/chronic fatigue syndrome.

Comparative Gut Microbiome Alterations in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Long COVID-19 Syndrome.

Symptom, Functional, and Work Participation Profiles Among Racialized Canadians with Pre-Existing Mental Health Challenges and Long COVID: A Cross-Sectional Study.

Exploring differences in protein cargo of extracellular vesicles from ME/CFS patient plasma compared to healthy controls.

Association between light exposure patterns and multidimensional health outcomes in individuals with myalgic encephalomyelitis/chronic fatigue syndrome: findings from an observational cross-sectional cohort study.

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