ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

2795 studies

81–100 of 2,795 studies

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 unclearCross-Sectional

Differences in diagnostic coding in long COVID: sociodemographic and symptom interference factors.

Vickers, Jasmine K, Levitan, Emily B, Howell, Carrie R et al.·BMC infectious diseases·2026

Researchers surveyed 205 people with Long COVID to understand how severe symptoms interfere with daily life and whether their condition was formally recorded in medical records. They found that people reporting high symptom interference were more likely to be older, female, obese, or in poor general health—but among those with severe symptoms, having an official Long COVID diagnosis code in their medical record was not associated with these demographic factors. The study observed discrepancies between what patients reported and what appeared in their medical records, though researchers did not find evidence that doctors were coding the diagnosis based on demographic bias.

Diagnostics

E2 ModerateCohortPEM requiredObservational

Handgrip strength in children, adolescents, and young adults with suspected myalgic encephalomyelitis/chronic fatigue syndrome.

Mihatsch, Lorenz, Schartner, Lisa, de Luna, Julia Lange et al.·Journal of translational medicine·2026

Researchers tested whether handgrip strength could help identify ME/CFS in young people (ages 10–25). They asked 147 patients referred for ME/CFS assessment and 83 healthy controls to squeeze a hand-strength device twice, an hour apart. Young people with ME/CFS had weaker grip strength than healthy controls, and grip strength was loosely associated with physical functioning; however, grip strength alone could not reliably tell apart ME/CFS patients from other young people with chronic fatigue. The study shows that repeated handgrip testing is feasible and may help track how patients are doing over time, but early findings suggest it works better as a way to measure general weakness rather than as a standalone diagnostic test.

BiomarkersDiagnosticsPost-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

Metabolomic Classification of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome via Explainable Ensemble Learning and Pareto-Guided Feature Selection.

Yagin, Fatma Hilal, Korkmaz, Yavuz, Colak, Cemil et al.·International journal of molecular sciences·2026

Researchers analysed blood metabolite patterns (small molecules in blood) from 106 people with ME/CFS and 91 healthy controls using machine learning to see whether these patterns could distinguish ME/CFS from health. A computer model called Explainable Boosting Machine achieved 91% accuracy in this one study group. Importantly, the findings remain preliminary—they describe associations observed in this cross-sectional sample and require external validation in new populations before clinical use.

BiomarkersEnergy MetabolismDiagnostics

E2 ModerateCohortPEM unclearCross-Sectional

Item comprehension and content coverage of patient-reported outcome measures for long COVID: a qualitative study.

Zigler, Christina K, Yousefian, Charis, Mangrum, Rikki et al.·Quality of life research : an international journal of quality of life aspects of treatment, care and rehabilitation·2026

Researchers asked 30 adults with Long COVID to review four existing survey questionnaires to see if the questions were clear and relevant to their condition. Participants reported they could understand most questions and found them relevant to their experiences. The study also identified ways these surveys could be improved, such as simplifying instructions and shortening length. These are preliminary findings from one qualitative study, and further testing of these surveys is planned.

Autonomic Nervous SystemDiagnosticsCognitive ImpairmentPost-Exertional Malaise

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 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

Associated factors and a risk prediction model for comorbid circadian rhythm sleep-wake disorders in patients with chronic fatigue syndrome: implications for early screening and sleep health management.

Shao, Xiao, Yang, Fan, Qin, Le-le et al.·Frontiers in psychiatry·2026

This observational study of 610 ME/CFS patients found that roughly half also had circadian rhythm sleep-wake disorders (difficulty sleeping at normal times). The researchers identified several factors associated with this comorbidity, including female sex, higher fatigue severity, certain shift work patterns, and reduced deep sleep. They developed a prediction model to help identify patients at higher risk, though the study's retrospective design and unknown case definition quality mean these findings are preliminary and require validation in other patient populations.

Sleep

E2 ModerateCohortPEM unclearCross-Sectional

Identifying EEG biomarkers of fatigue and brain fog in long COVID: insights from rest and movement-related brain activity.

Casado Sánchez, M, Morales Fajardo, K, Long, S et al.·Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia·2026

A small study measured brain electrical activity in 20 people with long COVID who reported fatigue and brain fog, compared to 20 healthy controls. Researchers observed two types of altered brain patterns in the long COVID group: weaker electrical responses after hand movements and slower brain waves at rest in motor and sensory regions. These patterns were associated with cognitive symptoms and fatigue, but it remains unclear whether these brain changes explain the symptoms or are simply observed alongside them.

BiomarkersCognitive Impairment

E2 ModerateCohortPEM unclearObservational

Haptoglobin Phenotypes Stratify Post-Exertional Cognitive Dysfunction Associated with Altered Cerebral Oxygenation and Metabolic Signatures in Long COVID.

Moezzi, Atefeh, Elremaly, Wesam, Leveau, Corinne et al.·International journal of molecular sciences·2026

This study observed that Long COVID patients with different versions of a protein called haptoglobin showed different patterns of cognitive problems after physical exertion. Patients carrying certain haptoglobin variants (Hp2) reported worse fatigue and cognitive decline following a challenge test, while those with the Hp1-1 variant showed better cognitive resilience. The findings are preliminary and come from a small group; larger studies are needed to confirm whether haptoglobin type could help identify which Long COVID patients are at higher risk for these cognitive changes.

BiomarkersEnergy MetabolismCognitive ImpairmentLong COVID Overlap

E2 ModerateBehavioralPEM not requiredCase-Control

Increased Disease Burden in Irritable Bowel Syndrome With Comorbid Conditions and Psychiatric Diagnoses in a Multinational European Cohort: Results From the DISCOvERIE Project.

Midenfjord, Irina, Khadija, Mahrukh, Sundelin, Elias et al.·United European gastroenterology journal·2026

This study looked at 607 patients with irritable bowel syndrome (IBS) across nine European centers to understand how other conditions—like anxiety, depression, fibromyalgia, and chronic fatigue syndrome—affect their symptoms and overall health. Patients who had IBS along with one or more of these comorbid conditions experienced more severe digestive symptoms, mood problems, and fatigue than those with IBS alone. The more comorbidities someone had, the worse their symptoms became.

Pain and Sensitization

E2 ModerateCohortPEM unclearCross-Sectional

Depressive and anxiety symptoms in current, previous, and no history of ME/CFS: NHIS 2022 analysis.

Sirotiak, Zoe, Adamowicz, Jenna L, Thomas, Emily B K·Quality of life research : an international journal of quality of life aspects of treatment, care and rehabilitation·2025

This study looked at anxiety and depression in people with ME/CFS using data from a large U.S. health survey. Researchers found that people currently living with ME/CFS reported much higher rates of anxiety and depression compared to people without ME/CFS. Interestingly, people who previously had ME/CFS but have since recovered still reported higher anxiety and depression rates than those who never had the illness, though the rates were lower than for those with current ME/CFS.

E2 ModerateCohortPEM requiredCross-Sectional

Concentrations of uremic bacterial metabolites in patients with post-COVID-19 syndrome.

Brigo, Natascha, Mayr, Wolfram, Taenzer, Maja et al.·Frontiers in cellular and infection microbiology·2025

This small study looked at special waste products made by gut bacteria in the urine of people with long COVID, ME/CFS, and healthy people. Researchers found that people with long COVID and ME/CFS had different patterns of these bacterial products compared to healthy controls, and these patterns might be connected to their symptoms like fatigue and post-exertional malaise (feeling much worse after activity).

Post-Exertional Malaise

E2 ModerateCohortPEM requiredObservational

The Clinical Relevance of Mast Cell Activation in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Rohrhofer, Johanna, Ebner, Lilian, Schweighardt, Johannes et al.·Diagnostics (Basel, Switzerland)·2025

This study looked at whether mast cells—immune cells that release chemicals causing inflammation—play a role in ME/CFS. Researchers surveyed 687 ME/CFS patients and reviewed records from 383 others, finding that about 25% had signs of problematic mast cell activation. Importantly, patients with mast cell problems who received targeted treatment reported better symptom relief than those without mast cell involvement, suggesting this might be a treatable subtype of ME/CFS.

Immune SystemPost-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

Circulating cell-free RNA signatures for the characterization and diagnosis of myalgic encephalomyelitis/chronic fatigue syndrome.

Gardella, Anne E, Eweis-LaBolle, Daniel, Loy, Conor J et al.·Proceedings of the National Academy of Sciences of the United States of America·2025

Researchers analyzed tiny pieces of RNA floating in the blood of people with ME/CFS and compared them to healthy people. They used a computer program to identify a pattern of these RNA pieces that could help diagnose ME/CFS with 77% accuracy. The study found that people with ME/CFS have different levels of immune cells releasing material into their blood, suggesting the immune system is behaving differently.

Immune System

E2 ModerateBehavioralPEM not requiredCross-Sectional

Network structure of functional somatic symptoms.

Litzenburger, Alexandra, Rothacher, Yannick, Hanusch, Kay-Uwe et al.·Journal of psychosomatic research·2025

This study looked at how symptoms cluster together in people with functional somatic syndromes (like ME/CFS, fibromyalgia, and others). Researchers surveyed over 3,000 young adults and used network analysis to map which symptoms tend to appear together. They found that fatigue and depression are particularly important symptoms that connect different symptom groups, and identified ten distinct clusters of related symptoms.

Pain and SensitizationCognitive Impairment

E2 ModerateDiagnosticPEM unclearCross-Sectional

Psychometric evaluation of the PROMIS® physical function short form 12a for use by adults with myalgic encephalomyelitis/chronic fatigue syndrome.

Yang, Manshu, Keller, San, Rafiee, Parisa et al.·Health and quality of life outcomes·2025

Researchers tested whether a questionnaire called PROMIS Physical Function Short Form (PF-SF) works well for measuring how much ME/CFS affects a person's ability to do physical activities. They asked 173 people with ME/CFS and 161 healthy people to complete the questionnaire and found that it accurately captured the differences in physical ability between the two groups. The questionnaire appears to be a reliable and useful tool for doctors and researchers to measure physical function in people with ME/CFS.

E2 ModerateBehavioralPEM unclearCase-Control

Bipolar spectrum, hypothyroidism, and their association with chronic fatigue/myalgic encephalomyelitis-like syndrome in long COVID: could they be identified as early determinants?

Tusconi, Massimo, Dursun, Serdar M, Pegreffi, Francesco et al.·Frontiers in psychiatry·2025

This study found that people with long COVID who developed ME/CFS-like symptoms were much more likely to have had hypothyroidism (an underactive thyroid) or bipolar spectrum disorders before getting sick compared to people from before the pandemic. The researchers suggest these pre-existing conditions might make someone more vulnerable to developing ME/CFS after COVID-19, possibly because they affect sleep rhythms and immune function.

E2 ModerateBehavioralPEM not requiredLongitudinal

Risk factors for fatigue severity in the post-COVID-19 condition: A prospective controlled cohort study of nonhospitalised adolescents and young adults.

Selvakumar, Joel, Havdal, Lise Beier, Brodwall, Elias Myrstad et al.·Brain, behavior, & immunity - health·2025

This study followed young people (ages 12–25) who had COVID-19 to understand why some develop long-lasting fatigue while others recover well. Researchers found that how severe symptoms were in the first few weeks after infection—and psychological factors like loneliness and worry—were much stronger predictors of ongoing fatigue at 6 months than any blood test or physical measure. Surprisingly, whether someone actually had COVID-19 made only a small difference; other life circumstances and emotional stress mattered more.

E2 ModerateCohortPEM not requiredCross-Sectional

Abnormal breathing patterns and hyperventilation are common in patients with chronic fatigue syndrome during exercise.

Mancini, Donna M, Brunjes, Danielle L, Cook, Dane et al.·Frontiers in medicine·2025

Researchers studied how patients with ME/CFS breathe during exercise and found that many breathe abnormally in ways that healthy people do not. Specifically, 42% of ME/CFS patients showed irregular breathing patterns, and 32% were breathing too fast and too deeply (hyperventilation). These breathing problems were much more common in ME/CFS patients than in the healthy control group, suggesting that abnormal breathing may be contributing to the fatigue and breathlessness patients experience.

Post-Exertional Malaise

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

Differences in diagnostic coding in long COVID: sociodemographic and symptom interference factors.

Handgrip strength in children, adolescents, and young adults with suspected myalgic encephalomyelitis/chronic fatigue syndrome.

Metabolomic Classification of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome via Explainable Ensemble Learning and Pareto-Guided Feature Selection.

Item comprehension and content coverage of patient-reported outcome measures for long COVID: a qualitative study.

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

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

Associated factors and a risk prediction model for comorbid circadian rhythm sleep-wake disorders in patients with chronic fatigue syndrome: implications for early screening and sleep health management.

Identifying EEG biomarkers of fatigue and brain fog in long COVID: insights from rest and movement-related brain activity.

Haptoglobin Phenotypes Stratify Post-Exertional Cognitive Dysfunction Associated with Altered Cerebral Oxygenation and Metabolic Signatures in Long COVID.

Increased Disease Burden in Irritable Bowel Syndrome With Comorbid Conditions and Psychiatric Diagnoses in a Multinational European Cohort: Results From the DISCOvERIE Project.

Depressive and anxiety symptoms in current, previous, and no history of ME/CFS: NHIS 2022 analysis.

Concentrations of uremic bacterial metabolites in patients with post-COVID-19 syndrome.

The Clinical Relevance of Mast Cell Activation in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Circulating cell-free RNA signatures for the characterization and diagnosis of myalgic encephalomyelitis/chronic fatigue syndrome.

Network structure of functional somatic symptoms.

Psychometric evaluation of the PROMIS® physical function short form 12a for use by adults with myalgic encephalomyelitis/chronic fatigue syndrome.

Bipolar spectrum, hypothyroidism, and their association with chronic fatigue/myalgic encephalomyelitis-like syndrome in long COVID: could they be identified as early determinants?

Risk factors for fatigue severity in the post-COVID-19 condition: A prospective controlled cohort study of nonhospitalised adolescents and young adults.

Abnormal breathing patterns and hyperventilation are common in patients with chronic fatigue syndrome during exercise.

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