ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

141–160 of 729 studies

E2 ModerateCohortPEM requiredLongitudinal

Post-discharge sequelae of Lassa fever survivors in Nigeria: an analysis of the LASCOPE prospective cohort.

Guichard, Eva, Juchet, Sylvain, Etafo, Ijeoma Chukwudumebi et al.·The Lancet. Infectious diseases·2026

This study followed 882 people who recovered from Lassa fever (a serious viral infection) after hospital discharge to see what long-term symptoms they experienced. Most survivors felt better within about 3 weeks after leaving the hospital, with the most common lingering symptoms being tiredness, headaches, and difficulty with physical activity. The good news is that serious complications like hearing loss were rare, affecting only 2% of survivors.

Post-Exertional Malaise

E2 ModerateCohortPEM unclearLongitudinal

Post-Acute Sequelae of COVID-19 Persist Over 3 Years in Acute Lung Injury/Acute Respiratory Distress Syndrome Survivors But Are Not Associated With Persistent Thromboinflammation or Endothelial Dysfunction.

Jones, Ansley E, Khan, Zain, McGroder, Claire F et al.·Critical care explorations·2026

This study followed people who were hospitalized with severe COVID-19 for 3 years after they left the hospital. About one-quarter of them continued to experience long COVID symptoms like fatigue, brain fog, and difficulty with physical activity. Surprisingly, when researchers measured inflammation and blood vessel markers in their blood, these markers were not elevated and did not explain why some people had ongoing symptoms.

BiomarkersImmune SystemPost-Exertional Malaise

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 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 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 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

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 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

Brain and muscle chemistry in myalgic encephalitis/chronic fatigue syndrome (ME/CFS) and long COVID: a 7T magnetic resonance spectroscopy study.

Godlewska, Beata R, Sylvester, Amy L, Emir, Uzay E et al.·Molecular psychiatry·2025

Researchers used advanced brain scans to look at chemical differences in the brains and muscles of people with ME/CFS, long COVID, and healthy people. They found that people with ME/CFS had higher levels of lactate (a chemical related to energy use) in specific brain areas, suggesting their brains may be working harder to produce energy. People with long COVID showed different changes - lower levels of a chemical called choline in the brain. These findings suggest that ME/CFS and long COVID may have different underlying causes, even though they produce similar symptoms.

Post-Exertional Malaise

E2 ModerateCohortPEM requiredCross-Sectional

Exploration of Intersections and Divergences of Long COVID and Chronic Fatigue Syndrome.

Kouyoumdjian, Joao A, Yamamoto, Leticia A, Graca, Carla R·Cureus·2025

This study looked at how Long COVID and ME/CFS might be related by comparing people with Long COVID symptoms to those without and healthy controls. While many Long COVID patients experienced symptoms that overlap with ME/CFS—like post-exertional malaise (feeling worse after activity), brain fog, and sleep problems—only about 1 in 5 Long COVID patients actually met the official diagnostic criteria for ME/CFS. The findings suggest that Long COVID and ME/CFS are related but distinct conditions.

Post-Exertional Malaise

E2 ModerateCohortPEM not requiredCross-Sectional

Cardio-Respiratory Fitness and Fatigue in Post-COVID-19 Syndrome-A Three-Year Update.

Cherneva, Radostina, Cherneva, Zheyna, Youroukova, Vania et al.·Biomedicines·2025

More than two years after COVID-19 infection, about a quarter of people still experience persistent symptoms including fatigue, breathing problems, and reduced ability to exercise. Researchers tested how well patients' hearts and lungs worked during exercise and found that those with moderate-to-severe symptoms had noticeably reduced fitness levels and felt more exhausted even when not working as hard as their test results showed they should be.

Post-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

A patient-centered view of symptoms, functional impact, and priorities in post-COVID-19 syndrome: cross-sectional results from the Québec Action Post-COVID cohort.

Mayo, Nancy E, Brouillette, Marie-Josée, Falcone, Emilia Liana et al.·BMC infectious diseases·2025

This study surveyed 535 people in Quebec living with long-term COVID symptoms to understand what symptoms they experience, how much these symptoms affect their daily lives, and what treatments matter most to them. The most common symptom was fatigue, and people reported symptoms affecting multiple body systems. Most participants had been dealing with symptoms for over a year, and the impact on their quality of life was significant.

Post-Exertional Malaise

E2 ModerateCohortPEM requiredObservational

Post-exertional malaise in Long COVID: subjective reporting versus objective assessment.

Stussman, Barbara, Camarillo, Nathan, McCrossin, Gayle et al.·Frontiers in neurology·2025

This study looked at post-exertional malaise (PEM)—the symptom worsening that happens after activity—in people with Long COVID. Researchers asked patients about PEM symptoms and had some patients do an exercise test to see if PEM actually occurred. While 67% of patients reported having PEM symptoms, only 6% actually showed clear PEM after the exercise test. When PEM did occur in Long COVID, it was less severe than what the researchers saw in ME/CFS patients.

Severe MEPost-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

Deoxygenation Trends and Their Multivariate Association with Self-Reported Fatigue in Post-COVID Syndrome.

Ladek, Anja-Maria, Lucio, Marianna, Weiß, Andreas et al.·Biomedicines·2025

This study looked at oxygen levels in the muscles of 100 people with long COVID and 50 healthy controls while they performed light exercise (squeezing a stress ball). The researchers used a special non-invasive scan called NIRS to measure this. People with long COVID, especially those with post-exertional malaise, showed abnormal oxygen patterns in their muscles compared to healthy people, and this was linked to their fatigue levels.

Post-Exertional Malaise

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

E2 ModerateCohortPEM unclearCross-Sectional

Clinical and Laboratory Characteristics of Fatigue-Dominant Long-COVID Subjects: A Cross-Sectional Study.

Lee, Jin-Seok, Choi, Yujin, Joung, Jin-Yong et al.·The American journal of medicine·2025

This study looked at 100 people with long COVID who experience significant ongoing fatigue, similar to ME/CFS. Researchers measured fatigue levels and checked blood levels of cortisol (a stress hormone) and other immune markers. They found that people with lower cortisol levels reported worse fatigue and lower quality of life, suggesting a possible connection between this hormone and fatigue severity.

Immune SystemPost-Exertional Malaise

E2 ModerateCohortPEM unclearObservational

Oral minocycline therapy as first-line treatment in patients with Myalgic encephalomyelitis and long COVID: A pilot study.

Miwa, Kunihisa·eNeurologicalSci·2025

This small study looked at whether a common antibiotic called minocycline might help people with ME/CFS, including those with long COVID. Fifty-five patients took minocycline for about 6 weeks, and 80% of those who completed the treatment reported meaningful improvements in their symptoms like fatigue, brain fog, and sleep problems. The treatment worked best for people early in their illness (within 6 months of symptom onset).

Post-Exertional Malaise

E2 ModerateCohortPEM unclearLongitudinal

Gastrointestinal Barrier Disruption in Post-COVID Syndrome Fatigue Patients.

Rohrhofer, Johanna, Wolflehner, Viktoria, Schweighardt, Johannes et al.·Allergy·2025

This study looked at whether problems with the digestive system might help explain why some people develop long-lasting fatigue and other symptoms after COVID-19 (post-COVID syndrome). The researchers found that people with post-COVID fatigue had signs of gut inflammation and a leaky intestinal barrier, along with changes in immune markers in their blood. This suggests that COVID-19 may damage the gut in ways that contribute to long-term fatigue and post-exertional malaise.

Immune SystemPost-Exertional Malaise

E2 ModerateCohortPEM not requiredObservational

Replicated blood-based biomarkers for myalgic encephalomyelitis not explicable by inactivity.

Beentjes, Sjoerd Viktor, Miralles Méharon, Artur, Kaczmarczyk, Julia et al.·EMBO molecular medicine·2025

Researchers found multiple blood markers that distinguish ME/CFS patients from healthy people, including signs of inflammation, insulin problems, and liver issues. Importantly, these differences were NOT caused by patients being physically inactive—they are genuine biological changes related to the disease itself. While no single blood test can diagnose ME/CFS yet, these findings suggest that a combination of blood markers could eventually provide objective diagnosis.

Post-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

A Signal for Voice and Speech Abnormalities in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Grach, Stephanie L, Seltzer, Jaime, Orbelo, Diana M·Journal of clinical medicine·2025

This study explored whether people with ME/CFS experience changes in their voice or speech. Researchers surveyed 685 people with ME/CFS and reviewed open-ended responses from 302 participants. About 9% of respondents mentioned voice or speech changes when describing their disease experience, suggesting this is a real symptom that deserves further attention.

Post-Exertional Malaise

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Post-discharge sequelae of Lassa fever survivors in Nigeria: an analysis of the LASCOPE prospective cohort.

Post-Acute Sequelae of COVID-19 Persist Over 3 Years in Acute Lung Injury/Acute Respiratory Distress Syndrome Survivors But Are Not Associated With Persistent Thromboinflammation or Endothelial Dysfunction.

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

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

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

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

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

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

Brain and muscle chemistry in myalgic encephalitis/chronic fatigue syndrome (ME/CFS) and long COVID: a 7T magnetic resonance spectroscopy study.

Exploration of Intersections and Divergences of Long COVID and Chronic Fatigue Syndrome.

Cardio-Respiratory Fitness and Fatigue in Post-COVID-19 Syndrome-A Three-Year Update.

A patient-centered view of symptoms, functional impact, and priorities in post-COVID-19 syndrome: cross-sectional results from the Québec Action Post-COVID cohort.

Post-exertional malaise in Long COVID: subjective reporting versus objective assessment.

Deoxygenation Trends and Their Multivariate Association with Self-Reported Fatigue in Post-COVID Syndrome.

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

Clinical and Laboratory Characteristics of Fatigue-Dominant Long-COVID Subjects: A Cross-Sectional Study.

Oral minocycline therapy as first-line treatment in patients with Myalgic encephalomyelitis and long COVID: A pilot study.

Gastrointestinal Barrier Disruption in Post-COVID Syndrome Fatigue Patients.

Replicated blood-based biomarkers for myalgic encephalomyelitis not explicable by inactivity.

A Signal for Voice and Speech Abnormalities in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

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