ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

2768 studies

21–40 of 2,768 studies

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 unclearLongitudinal

Chronic Reactivation of Persistent Human Herpesviruses EBV, HHV-6 and VZV and Heightened Anti-dUTPase IgG Antibodies Are a Recurrent Hallmark in Post-Infectious ME/CFS and is Associated With Fatigue.

Palomo, Irene Mena, Cox, Brandon, Williams, Marshall V et al.·Journal of medical virology·2026

This study found that people with ME/CFS have higher levels of immune responses to three common viruses (EBV, HHV-6, and VZV) compared to healthy people. About 72% of ME/CFS patients showed antibodies to multiple viruses at the same time, versus only 31% of healthy controls. The antibody levels were higher in patients with moderate to severe fatigue, suggesting a possible connection between these viral reactivations and symptom severity.

BiomarkersImmune System

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 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 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 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 unclearCross-Sectional

Assessment of dynamic cerebral blood flow changes during cognitive tasks in patients with post-COVID-19 syndrome.

Kutz, Dieter F, Garbsch, René, Mooren, Frank C et al.·Brain communications·2026

This study looked at how blood flow in the brain changes when people with post-COVID-19 syndrome try to do mental tasks. Researchers used special infrared cameras to watch blood flow in the thinking part of the brain while patients did concentration exercises. They found that people with post-COVID-19 had unusual, less flexible blood flow patterns compared to healthy people, which may help explain why they feel mentally tired and have trouble concentrating.

Cognitive Impairment

E2 ModerateBehavioralPEM not requiredCross-Sectional

Disentangling comorbidity: symptom dimensions of internalizing and functional disorders in a large general population sample.

Saini, Urvi, Aggen, Steven H, Oldehinkel, Albertine J et al.·BMC psychiatry·2026

This study looked at how symptoms of depression, anxiety, ME/CFS, fibromyalgia, and irritable bowel syndrome overlap in over 100,000 people. Researchers found that these conditions share common symptoms like fatigue, sleep problems, and difficulty concentrating—which they call 'general malaise'—rather than being completely separate diseases. Understanding these shared symptoms may help explain why people often have multiple conditions at the same time.

Pain and SensitizationCognitive 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 requiredObservational

Assessment and Incidence Determination of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Following a SARS-CoV-2 Infection in a Prospective Cohort of Hospital Employees.

Tack, Matthias, Gruber, Rosalie, Betting, Leia et al.·Medicina (Kaunas, Lithuania)·2026

This study followed hospital workers who got COVID-19 to see how many developed long-lasting fatigue and ME/CFS. About 12% still had fatigue months later, and 3% met the criteria for ME/CFS. Researchers found that people with these conditions often had signs of viral reactivation, immune system changes, and blood clotting abnormalities.

Post-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

Chronic Pain Prevalence, Characteristics, and Impact in United States Adults With Chronic Fatigue Syndrome/Myalgic Encephalomyelitis.

Adamowicz, Jenna L, Sirotiak, Zoe, Lendvai, Dora et al.·Pain management nursing : official journal of the American Society of Pain Management Nurses·2026

This study looked at how common chronic pain is in people with ME/CFS and how it affects their lives. Researchers found that about 7 out of 10 people with ME/CFS also experience chronic pain lasting months or longer. People with both ME/CFS and chronic pain reported more depression, anxiety, and difficulty with daily activities compared to people who only have chronic pain.

Pain and Sensitization

E2 ModerateCohortPEM requiredObservational

Postexertional Symptom Exacerbation after Submaximal Exercise in Individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Postacute Sequelae of COVID-19.

Berardi, Giovanni, Janowski, Adam, McNally, Samuel et al.·Medicine and science in sports and exercise·2026

This study looked at what happens when people with ME/CFS or long COVID do moderate exercise. Researchers asked 60 patients and 30 healthy people to exercise for 25 minutes, then tracked their symptoms for a week. Most patients with ME/CFS experienced worsening fatigue, mental fog, and other symptoms in the days after exercise, but the severity and which symptoms got worse varied from person to person.

Post-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

Understanding concussion in myalgic encephalomyelitis/chronic fatigue syndrome: Findings from the 2023 National Health Interview study.

Sirotiak, Zoe, Adamowicz, Jenna L, Thomas, Emily B K·Brain injury·2026

This study found that people with ME/CFS are nearly 5 times more likely to have had a concussion in the past year compared to people without ME/CFS. People with ME/CFS also experienced more falls and dizziness or balance problems. The researchers suggest that doctors should screen patients with ME/CFS more carefully for concussions and take steps to reduce their concussion risk.

Autonomic Nervous System

E2 ModerateCohortPEM unclearCross-Sectional

Charting the circulating proteome in ME/CFS using cross-system profiling to uncover mechanistic insights.

Hoel, August, Hoel, Fredrik, Dyrstad, Sissel Elisabeth et al.·Cell reports. Medicine·2026

Researchers analyzed thousands of proteins in the blood of ME/CFS patients and compared them to healthy people. They found significant differences in protein patterns, including too much of certain immune-related proteins and too little of proteins normally made by muscles. These differences might help explain why ME/CFS causes such severe exhaustion and could eventually lead to new ways to diagnose or treat the condition.

BiomarkersImmune System

E2 ModerateCohortPEM unclearCross-Sectional

Hypermethylation of OPRM1: Deregulation of the Endogenous Opioid Pathway in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Fibromyalgia.

Wyns, Arne, Hendrix, Jolien, Van Campenhout, Jente et al.·International journal of molecular sciences·2026

This study examined whether changes in how a gene called OPRM1 (which controls opioid receptors in the body) are chemically marked in people with ME/CFS and fibromyalgia. Researchers found that people with these conditions had higher levels of these chemical marks on the OPRM1 gene compared to healthy people, even after accounting for how severe their symptoms were. This suggests that problems with the body's natural pain-relief system may be a fundamental part of these illnesses.

E2 ModerateDiagnosticPEM unclearCross-Sectional

Improving myalgic encephalomyelitis population sampling: Applying an online respondent-driven method to address biases in G93.3 register data.

Kielland, Anne, Liu, Jing, Tyldum, Guri et al.·Journal of health psychology·2026

This study looked at how well official medical records capture ME/CFS cases and who gets diagnosed. Researchers found that medical register data misses many cases and disproportionately underrepresents people from lower-income backgrounds. They used a new online method to find ME/CFS patients more accurately and checked whether official diagnoses matched recognized diagnostic criteria.

Diagnostics

E2 ModerateCohortPEM unclearLongitudinal

Validation of the Wood Mental Fatigue Inventory in adolescents with myalgic encephalomyelitis/chronic fatigue syndrome.

Welch, David C, Edwards, Charles C, Broussard, Camille A et al.·Brain, behavior, & immunity - health·2026

This study tested whether a questionnaire called the Wood Mental Fatigue Inventory (WMFI) works well for measuring brain fog and cognitive problems in teenagers with ME/CFS. Researchers compared it to another commonly used teen fatigue scale and found that both questionnaires measured mental fatigue similarly and could track changes over time as teenagers received treatment.

Cognitive Impairment

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

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

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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.

Chronic Reactivation of Persistent Human Herpesviruses EBV, HHV-6 and VZV and Heightened Anti-dUTPase IgG Antibodies Are a Recurrent Hallmark in Post-Infectious ME/CFS and is Associated With Fatigue.

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

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

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

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

Assessment of dynamic cerebral blood flow changes during cognitive tasks in patients with post-COVID-19 syndrome.

Disentangling comorbidity: symptom dimensions of internalizing and functional disorders in a large general population sample.

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

Assessment and Incidence Determination of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Following a SARS-CoV-2 Infection in a Prospective Cohort of Hospital Employees.

Chronic Pain Prevalence, Characteristics, and Impact in United States Adults With Chronic Fatigue Syndrome/Myalgic Encephalomyelitis.

Postexertional Symptom Exacerbation after Submaximal Exercise in Individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Postacute Sequelae of COVID-19.

Understanding concussion in myalgic encephalomyelitis/chronic fatigue syndrome: Findings from the 2023 National Health Interview study.

Charting the circulating proteome in ME/CFS using cross-system profiling to uncover mechanistic insights.

Hypermethylation of OPRM1: Deregulation of the Endogenous Opioid Pathway in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Fibromyalgia.

Improving myalgic encephalomyelitis population sampling: Applying an online respondent-driven method to address biases in G93.3 register data.

Validation of the Wood Mental Fatigue Inventory in adolescents with myalgic encephalomyelitis/chronic fatigue syndrome.

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

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

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