ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

1061–1080 of 6,209 studies

E2 ModerateCohortPEM requiredObservational

[The Role of ME/CFS Phenotype in Outpatient Post-COVID Rehabilitation].

Kaiserseder, Moritz, Prüfer, Ferdinand, Untersmayer-Elsenhuber, Eva et al.·Pneumologie (Stuttgart, Germany)·2026

This study looked at 216 people recovering from COVID-19 in rehabilitation programs to see how many had ME/CFS—a condition with severe fatigue and worsening after physical activity. The researchers found that about 7% of these patients met the criteria for ME/CFS. These patients were typically younger, mostly women, and experienced much more severe fatigue that didn't improve with rehabilitation compared to other COVID-19 patients.

Post-Exertional Malaise

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 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 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 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

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 requiredCross-Sectional

Impact of post-exertional malaise frequency and fatigue in Long COVID patients on health-related quality of life.

Thölking, Theresa, Müller, Frank, Riester, Tim et al.·Health and quality of life outcomes·2026

This study surveyed German adults with Long COVID and post-exertional malaise (PEM) to understand how the frequency and severity of PEM relates to quality of life. Researchers found that people reporting more frequent and more severe PEM were associated with lower quality-of-life scores, even after accounting for age, sex, and employment status. These are preliminary findings from a single survey and do not establish that PEM causes poor quality of life, but rather that the two observations occurred together in this group.

Post-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome diagnostic reporting in the 2021-2023 National Health Interview Survey.

Fleig, Katherine, Nahin, Richard, Stussman, Barbara et al.·BMC public health·2026

A survey of over 86,000 US adults found that approximately 1.5% reported ever receiving an ME/CFS diagnosis. Among those, about 21% reported they no longer have the condition (Past ME/CFS), though roughly 40–50% of this group still experience symptoms and functional limitations similar to those currently diagnosed. This study observed that people who report having recovered from ME/CFS remain more impaired than those who never had the diagnosis, suggesting that reported recovery does not necessarily mean full symptom resolution.

Diagnostics

E2 ModerateCohortPEM unclearCross-Sectional

3D Virtual Reality Performance Metrics as a Future Fatigue Biomarker in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS).

Ladek, Anja-Maria, Priebe, Leonie, Harrer, Thomas et al.·Biomedicines·2026

Researchers tested how quickly 60 ME/CFS patients and 60 healthy controls could react to visual tasks presented in 3D virtual reality. ME/CFS patients showed slower reaction times across all difficulty levels, and they improved less with practice than controls did. The study reports an association between ME/CFS and prolonged reaction times, though the findings are preliminary and whether this could become a reliable test for fatigue severity requires further validation.

BiomarkersDiagnosticsCognitive Impairment

E2 ModerateCohortPEM not requiredObservational

Post-Exertional Malaise in Post-COVID-19 Syndrome: A Shift in the Frequency Across Pandemic Phases.

Ghali, Alaa, Lavigne, Christian, Ghali, Maria et al.·Journal of clinical medicine·2026

A French hospital study observed that post-COVID patients infected in 2020–2021 reported post-exertional malaise (PEM) more often than those infected later, and that PEM was associated with higher fatigue levels. By analogy, this may be relevant to ME/CFS patients, though the study examined post-COVID populations and the reasons for these differences remain uncertain—they could reflect changes in the virus, vaccination, immunity, or other unmeasured factors.

Long COVID OverlapPost-Exertional Malaise

E2 ModerateCohortPEM unclearLongitudinal

Outcomes of ME/CFS following infectious mononucleosis: seven-year follow-up of a prospective study.

Jason, Leonard A, Furst, Jacob, Worth, Rebecca et al.·Frontiers in medicine·2026

This study followed college students over 7 years to see what happened to those who developed ME/CFS after infectious mononucleosis caused by Epstein-Barr virus (EBV). Researchers found that people who had severe ME/CFS 6 months after their infection were very likely to still have ME/CFS 7 years later, while those with milder symptoms often recovered. This suggests that how sick someone is early on may predict whether ME/CFS will persist long-term.

E2 ModeratePEM unclearRegistry-Resource

Risk factors for severe post-COVID condition in children, adolescents, and young adults.

Donath, Quirin, Haegele, Matthias, Schindler, Daniela et al.·European journal of pediatrics·2026

This observational study from a German pediatric hospital followed 120 children and young adults with post-COVID condition (PCC), observing that those with more severe illness were more likely to have had 12 or more symptoms during their initial COVID-19 infection, alongside other acute symptoms such as trouble concentrating and fainting-like episodes. One quarter of participants met criteria for ME/CFS, and all of these were in the severely affected group; by analogy, if similar patterns apply to ME/CFS patients, early identification of high-symptom-burden acute illness might help predict who develops severe long-term illness. These findings are preliminary and come from a single hospital site.

Severe MEAutonomic Nervous SystemDiagnosticsCognitive Impairment

E2 ModerateCohortPEM unclearCross-Sectional

Involvement of autoantibodies against G protein-coupled receptors in post-COVID condition and Chronic Fatigue Syndrome.

Azcue, N, Prada, A, Del Pino, R et al.·Scientific reports·2026

Researchers compared immune markers called autoantibodies in people with post-COVID condition, ME/CFS, and healthy controls. They found that people with ME/CFS had higher levels of antibodies against certain nerve receptors (β2 adrenergic), and these antibodies were associated with autonomic nervous system problems and memory changes. However, this is a single cross-sectional study, and autoimmunity remains one of several proposed mechanisms—it is not yet clear whether these antibodies are a cause or a consequence of ME/CFS.

BiomarkersAutonomic Nervous SystemImmune SystemCognitive Impairment

E2 ModerateCohortPEM unclearCross-Sectional

Underuse of Pharmacologic Therapies for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Before Specialist Evaluation.

Grach, Stephanie L, Seltzer, Jaime, Mueller, Michael R et al.·Annals of family medicine·2026

A study of 571 ME/CFS patients in Minnesota found that about two-thirds had tried at least one medication before seeing a specialist, and over 70% had used dietary supplements. The researchers observed that medications commonly recommended by ME/CFS specialists—such as certain antidepressants and gabapentin—appear to be prescribed less often by general doctors compared to pain and anxiety medications. It remains unclear whether this pattern reflects clinical caution, lack of awareness, or other factors in primary care practice.

Interventions

E2 ModerateCohortPEM unclearCross-Sectional

Cardiopulmonary Exercise Testing Reveals Functional Limitations and Work Disability in Severe Post-COVID-19 and ME/CFS Patients.

Tomaskovic, Aleksandar, Weber, Vincent, Ochmann, David T et al.·Sports medicine - open·2026

A cross-sectional study of 92 severely ill post-COVID patients found that those meeting ME/CFS criteria had lower measured aerobic capacity (oxygen uptake and power output) on exercise testing compared to post-COVID patients without ME/CFS. Two-thirds of all patients showed objective signs of work disability on testing, and these measurements correlated with patients' own reports of disability and their employment status. The relevance of these findings specifically to ME/CFS requires caution, as the study enrolled primarily post-COVID patients, and the overlap between these conditions remains incompletely understood.

Severe MEDiagnosticsLong COVID OverlapPost-Exertional Malaise

E2 ModerateCohortPEM unclearObservational

Prediction of post-COVID chronic fatigue syndrome using data mining and machine learning techniques in Isfahan COVID cohort study.

Nematbakhsh, Shayan, Mohammadifard, Noushin, Riahi, Roya et al.·Journal of infection and public health·2026

Researchers used machine learning to identify factors associated with post-COVID fatigue in a cohort of 3,850 patients in Isfahan, Iran. The analysis identified 37 factors linked to fatigue; anxiety, BMI, depression, irritability, and memory issues were among the strongest predictors. A machine learning model achieved 85% accuracy at identifying patients at risk, though these results are based on observed associations and have not yet been validated in independent populations.

Diagnostics

E2 ModerateCohortPEM not requiredCross-Sectional

Persistent fatigue in long-COVID is not associated with peripheral inflammatory or cellular stress biomarkers: A cross-sectional controlled study.

Omdal, Roald, Lenning, Ole Bernt, Jonsson, Grete et al.·Brain, behavior, & immunity - health·2026

A study of 48 people with long-COVID and 48 recovered controls found that fatigue was much more severe in the long-COVID group, but common blood markers of inflammation and cellular stress did not differ between the groups. This suggests that the fatigue in long-COVID may not be driven by the types of inflammation typically measured in blood tests, though the researchers note their findings are preliminary and limited to the biomarkers they tested.

NeuroinflammationBiomarkersImmune SystemLong COVID Overlap

E2 ModerateCohortPEM unclearObservational

Facility-Measured Sleep Electroencephalographic Microstructures in Long COVID.

Sun, Haoqi, Dang, Rammy, Li, Peng et al.·Sleep·2026

Researchers used overnight brain-wave recordings (EEG) to examine sleep patterns in people with long COVID and ME/CFS, comparing them to healthy controls. They found that both groups showed altered patterns in specific brain-wave features during sleep—such as changes in slow waves and sleep spindles (brief bursts of brain activity)—that may be associated with the unrefreshing sleep and fatigue these patients report. However, this is one study in a specific research setting, and it remains unclear whether these brain-wave changes are a cause of the symptoms or simply occur alongside them.

BiomarkersSleepLong COVID Overlap

E2 ModerateCohortPEM unclearObservational

Testing a Personalised Dysautonomia Management Protocol in Patients with Orthostatic Intolerance and a Diagnosis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome or Long COVID.

Barr, Julia, Marsden, Lowri, Dassanayake, Theshan et al.·Journal of clinical medicine·2026

This observational study tested whether a personalised 8-week management plan (involving increased fluid and salt intake, pacing strategies, and calf exercises) was feasible and associated with symptom changes in 22 people with ME/CFS or Long COVID who experienced orthostatic intolerance. Reported improvements were modest: autonomic symptom scores improved by 7.7 points, and heart rate response during a standing test decreased slightly; however, adherence was highly variable, and the authors note that statistical improvements may not reflect clinically meaningful symptom relief. The study remains preliminary and cannot establish whether this protocol is an effective treatment.

InterventionsAutonomic Nervous System

E2 ModerateCohortPEM requiredCross-Sectional

Identifying post-exertional malaise subtypes: Differentiating physical and mental PEM manifestations.

Tuzzolino, Katherine, Jason, Leonard A, Furst, Jacob·Journal of health psychology·2026

This study looked at how post-exertional malaise (PEM)—the worsening of symptoms after activity—shows up differently in people with ME/CFS. Researchers divided patients into groups based on whether their PEM affected them physically (like muscle pain), mentally (like brain fog), both ways, or neither way severely. They found that people experiencing both physical and mental PEM had the worst overall symptoms, while those with neither type of severe PEM were less affected, though still much more disabled than healthy people.

Post-Exertional Malaise

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[The Role of ME/CFS Phenotype in Outpatient Post-COVID Rehabilitation].

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

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

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

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

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

Impact of post-exertional malaise frequency and fatigue in Long COVID patients on health-related quality of life.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome diagnostic reporting in the 2021-2023 National Health Interview Survey.

3D Virtual Reality Performance Metrics as a Future Fatigue Biomarker in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS).

Post-Exertional Malaise in Post-COVID-19 Syndrome: A Shift in the Frequency Across Pandemic Phases.

Outcomes of ME/CFS following infectious mononucleosis: seven-year follow-up of a prospective study.

Risk factors for severe post-COVID condition in children, adolescents, and young adults.

Involvement of autoantibodies against G protein-coupled receptors in post-COVID condition and Chronic Fatigue Syndrome.

Underuse of Pharmacologic Therapies for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Before Specialist Evaluation.

Cardiopulmonary Exercise Testing Reveals Functional Limitations and Work Disability in Severe Post-COVID-19 and ME/CFS Patients.

Prediction of post-COVID chronic fatigue syndrome using data mining and machine learning techniques in Isfahan COVID cohort study.

Persistent fatigue in long-COVID is not associated with peripheral inflammatory or cellular stress biomarkers: A cross-sectional controlled study.

Facility-Measured Sleep Electroencephalographic Microstructures in Long COVID.

Testing a Personalised Dysautonomia Management Protocol in Patients with Orthostatic Intolerance and a Diagnosis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome or Long COVID.

Identifying post-exertional malaise subtypes: Differentiating physical and mental PEM manifestations.

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