ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

1001–1020 of 6,187 studies

E2 ModerateCohortPEM unclearCross-Sectional

Heightened prevalence of chronic fatigue syndrome in U.S. sexual minorities.

Balshi, Alexandra, Dempsey, John P, Thompson, Hannah R et al.·Journal of psychiatric research·2026

This study looked at whether ME/CFS is more common in sexual minority adults (lesbian, gay, bisexual, and other non-heterosexual people) compared to heterosexual adults in the United States. Researchers found that about 2.4% of sexual minority adults reported ME/CFS, compared to 1.7% of heterosexual adults. Even after accounting for other health conditions and life factors, sexual minority adults had about 1.5 times higher odds of having ME/CFS.

E2 ModerateCohortPEM unclearObservational

Wearable Heart Rate Variability Monitoring, Autonomic Dysfunction and Post-exertional Malaise in Long COVID: An Observational Study.

Ruijgt, Twan M, Slaghekke, Anouk, Ellens, Anneke et al.·Sports medicine (Auckland, N.Z.)·2026

This observational study measured heart rate variability (a marker of nerve system balance) in 121 long COVID patients and 21 healthy controls using wearable devices over multiple days. Researchers observed that long COVID patients had lower heart rate variability during daily activities and sleep, and their heart rate variability remained reduced for 24 hours after exercise, particularly at intensities above their aerobic threshold. The findings suggest wearables may help patients recognise when they are overexerting, though the study does not yet establish whether this monitoring prevents post-exertional malaise.

BiomarkersAutonomic Nervous SystemDiagnosticsPost-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

Overlapping Clinical Presentation of Long COVID and Postacute COVID-19 Vaccination Syndrome: Phenotypes, Severity, and Biomarkers.

Purpura, Lawrence, Heisler, Thomas, Palmer, Steven et al.·Clinical infectious diseases : an official publication of the Infectious Diseases Society of America·2026

This study compared three groups of people dealing with long-term effects from COVID-19: those with long COVID and ME/CFS, those with long COVID without ME/CFS, and those with symptoms after COVID-19 vaccination. While all three groups shared common symptoms like fatigue, the ME/CFS group experienced more widespread symptoms across their body. Interestingly, people in the vaccination-related group had higher rates of unusual symptoms like nerve pain and rashes, and their blood tests showed different patterns of autoimmune markers—substances that suggest the immune system may be attacking the body's own tissues.

Immune System

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 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

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 ModerateBehavioralPEM not requiredObservational

The role of rehabilitation in Post-COVID-19 syndrome (PCS) recovery: An effectiveness study.

Collins, Gillian, Daly, Emma, Gallagher, David et al.·The British journal of occupational therapy·2026

This study tested whether a 6-week online rehabilitation program helped people recovering from long COVID. Thirty-six participants were tracked over 12 weeks—first during a waiting period where nothing changed, then during the rehabilitation program. The program, led by occupational therapists and physical therapists, taught practical strategies and provided peer support. Participants showed significant improvements in fatigue and symptom severity after completing the program.

E2 ModerateCohortPEM not requiredCross-Sectional

Clinical Importance of Central Sensitization and Neuropathic Pain in The Treatment and Follow-Up of Patients with Psoriasis and Psoriatic Arthritis.

Koca, Tuba Tülay, Göğebakan, Hasan, Nazik, Hülya et al.·Indian journal of dermatology·2026

This study looked at whether people with skin and joint conditions (psoriasis and psoriatic arthritis) experience unusual pain processing in their nervous system, similar to what happens in conditions like fibromyalgia. Researchers found that many patients with these conditions had signs of nervous system sensitization and neuropathic pain (nerve-related pain). The more active their disease was, the more likely they were to have these pain processing problems.

Pain and Sensitization

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 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 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

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 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 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

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 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 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 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 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 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

← Previous Next 20 studies →

Or browse by topic

PEM Immune Neuro Metabolic Biomarkers Severe ME Long COVID Cognitive

Evidence Atlas

Evidence browser

Heightened prevalence of chronic fatigue syndrome in U.S. sexual minorities.

Wearable Heart Rate Variability Monitoring, Autonomic Dysfunction and Post-exertional Malaise in Long COVID: An Observational Study.

Overlapping Clinical Presentation of Long COVID and Postacute COVID-19 Vaccination Syndrome: Phenotypes, Severity, and Biomarkers.

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

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

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

The role of rehabilitation in Post-COVID-19 syndrome (PCS) recovery: An effectiveness study.

Clinical Importance of Central Sensitization and Neuropathic Pain in The Treatment and Follow-Up of Patients with Psoriasis and Psoriatic Arthritis.

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

Facility-Measured Sleep Electroencephalographic Microstructures in Long COVID.

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

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

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

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

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

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

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

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

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

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

Curated Collections

Neuroinflammation Evidence

Metabolism & Mitochondria

Biomarkers

PEM-Specific Research