ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

1061–1080 of 6,157 studies

E2 ModerateCohortPEM requiredCross-Sectional

Fatigue, interoplastic and nociplastic distress in myalgic encephalomyelitis/chronic fatigue syndrome, Gulf War Illness, and chronic idiopathic fatigue.

Chen, Emily, Rudder, Tamera, Nwankwere, Charles et al.·Frontiers in neuroscience·2025

This study compared pain sensitivity and fatigue in people with ME/CFS, Gulf War Illness, and chronic fatigue to understand what causes their symptoms. Researchers found that people with ME/CFS and Gulf War Illness have increased pain sensitivity (measured by pressing on their skin), and their pain and internal body sensations are closely linked. However, pain sensitivity didn't strongly correlate with fatigue levels, suggesting that fatigue may involve different mechanisms than pain.

Post-Exertional Malaise

E2 ModerateCohortPEM unclearLongitudinal

Health outcomes up to 3 years and post-exertional malaise in patients after hospitalization for COVID-19: a multicentre prospective cohort study (CO-FLOW).

Berentschot, Julia C, Bek, L Martine, Drost, Manon et al.·The Lancet regional health. Europe·2025

This study followed 299 people hospitalized with COVID-19 for three years after discharge to track their recovery. While some improved over time, many people continued experiencing fatigue, memory problems, and cognitive difficulties—and these problems actually got worse between years 2 and 3. About one-third of patients developed post-exertional malaise (PEM), a condition where activity makes symptoms significantly worse, and these patients had more severe and persistent health problems throughout the study.

Post-Exertional Malaise

E2 ModerateCohortPEM unclearCross-Sectional

A Cross-Sectional Study of Symptom Prevalence, Frequency, Severity, and Impact of Long COVID in Scotland: Part I.

Mclaughlin, Marie, Cerexhe, Luke, Macdonald, Eilidh et al.·The American journal of medicine·2025

Researchers surveyed 253 people living with long COVID in Scotland to understand which symptoms are most common and how severe they are. The most frequent symptoms were post-exertional malaise (when activity makes symptoms worse), extreme tiredness, and thinking problems. The study found that people living in areas with more deprivation experienced more symptoms, but factors like vaccination status and age did not significantly affect symptom patterns.

Post-Exertional Malaise

E2 ModerateCohortPEM unclearCase-Control

Steroid dynamics in myalgic encephalomyelitis / chronic fatigue syndrome: a case-control study using ultra performance supercritical fluid chromatography tandem mass spectrometry.

Thomas, Natalie, Ubhayasekera, S J Kumari A, Armstrong, Christopher W et al.·Journal of translational medicine·2025

This study looked at stress hormones (steroids) in the blood of people with ME/CFS compared to healthy controls. While the amounts of individual hormones were similar between the two groups, the researchers found that the hormones were not communicating with each other properly in ME/CFS patients—like instruments in an orchestra playing out of sync. This suggests that the body's hormone regulation system may be disrupted in ME/CFS, even when individual hormone levels appear normal.

E2 ModerateCohortPEM requiredCross-Sectional

Serum Spike Protein Persistence Post COVID Is Not Associated with ME/CFS.

Fehrer, Annick, Sotzny, Franziska, Kim, Laura et al.·Journal of clinical medicine·2025

Researchers tested whether a piece of the COVID-19 virus (spike protein) lingering in the blood after infection could explain ME/CFS symptoms. They found spike protein in some patients' blood months after COVID, but it was present in similar amounts in people who recovered well and those with ME/CFS. This suggests that leftover spike protein is probably not the main cause of ME/CFS.

E2 ModerateCohortPEM not requiredObservational

Age-Related Changes in the Clinical Picture of Long COVID.

Fain, Mindy J, Horne, Benjamin D, Horwitz, Leora I et al.·Journal of the American Geriatrics Society·2025

This study looked at how Long COVID symptoms change as people get older. Researchers compared people aged 18–39 with those aged 40–70+ who had recovered from COVID-19 infection at least 135 days earlier. They found that middle-aged adults (40–59) were more likely to have Long COVID than young adults, but surprisingly, adults aged 70+ were actually less likely to report it—and when they did, their symptoms looked different, with less fatigue, pain, and brain fog compared to younger people.

Post-Exertional Malaise

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 ModerateBehavioralPEM not requiredLongitudinal

Prospective associations between major depressive disorder, generalized anxiety disorder, fibromyalgia, and myalgic encephalomyelitis/chronic fatigue syndrome.

Thomas, Nathaniel Stembridge, Neale, Michael C, Kendler, Kenneth S et al.·Psychological medicine·2025

This study followed over 100,000 people over time to understand how depression, anxiety, fibromyalgia, and ME/CFS relate to each other. The researchers found that these conditions tend to be connected, but the direction of the connection varies: fibromyalgia appears to lead to depression, while ME/CFS and depression seem to influence each other in both directions. The study suggests that these conditions should be studied separately rather than grouped together, since they may work differently.

E2 ModerateCohortPEM requiredCross-Sectional

Wearable technology in the management of complex chronic illness: preliminary survey results on self-reported outcomes.

Sawyer, Abbey, Preston, Rory, Leeming, Harry et al.·Frontiers in digital health·2025

This study looked at whether a smartphone app with a wearable armband helps people with ME/CFS and Long COVID manage their energy and symptoms. Over 1,300 people with these conditions used the app and answered questions about whether it helped them. Most people who used the app for at least a month reported feeling like they better understood their energy limits and how to manage daily activities, though some improvements may have simply come from tracking their own experience over time.

Post-Exertional Malaise

E2 ModerateCohortPEM unclearObservational

Immune Signatures in Post-Acute Sequelae of COVID-19 (PASC) and Myalgia/Chronic Fatigue Syndrome (ME/CFS): Insights from the Fecal Microbiome and Serum Cytokine Profiles.

Tobi, Martin, Chaudhari, Diptaraj, Ryan, Elizabeth P et al.·Biomolecules·2025

Researchers compared gut bacteria and immune molecules in the blood of people with long COVID and chronic fatigue syndrome. They found that people with these conditions have unusual patterns of gut bacteria and different levels of immune signaling molecules compared to healthy controls. These differences suggest the immune system and gut health may play a role in why some people develop long-lasting fatigue after infection.

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 ModerateCohortPEM not requiredCross-Sectional

The relationship between fatigue, sleep quality, and sleep deprivation.

Ayas, Fahriye Yonca, Özcebe, Lütfiye Hilal·Sleep & breathing = Schlaf & Atmung·2025

This study looked at how fatigue, sleep quality, and daytime sleepiness are connected in workplace employees. Researchers found that when people have poor sleep quality or don't sleep enough hours, they tend to experience more fatigue and daytime sleepiness—and these problems appear to affect each other in a cycle. The study suggests that addressing sleep problems may be important for reducing fatigue and improving workplace safety.

Sleep

E2 ModerateCohortPEM unclearCross-Sectional

Age-specific alterations of the gut mycobiome in patients with myalgic encephalomyelitis/chronic fatigue syndrome and identification of potential diagnostic biomarkers.

Gan, Yunong, Ning, Ruihong, Zhang, Wen et al.·BMC microbiology·2025

Researchers studied fungi living in the gut of ME/CFS patients compared to healthy people across different age groups. They found that people with ME/CFS have different types and amounts of gut fungi than healthy people, and these differences vary depending on age. Using these fungal patterns, they could identify ME/CFS patients with high accuracy—especially when looking at people of similar ages—suggesting gut fungi might help diagnose the condition.

Biomarkers

E2 ModerateCohortPEM unclearCross-Sectional

Assessing the Relationship in Symptomology of Myalgic Encephalitis/Chronic Fatigue Syndrome and Long COVID.

Garapaty, Nikitha, Reyes, Kristina M, Tehrani, Lily et al.·American journal of medicine open·2025

This study compared symptoms in people with ME/CFS, Long COVID, both conditions together, and people without either condition. Researchers found that people who have both ME/CFS and Long COVID experience the worst symptoms—including memory problems, anxiety, depression, fatigue, and difficulty exercising—compared to people with just one condition or neither. The findings suggest these two illnesses may interact in ways that make symptoms more severe when they occur together.

Cognitive Impairment

E2 ModerateCohortPEM unclearCross-Sectional

Quantifying the Degree of Fatigue in People Reporting Symptoms of Post-COVID-19 Syndrome: Results from a Rasch Analysis.

Mayo, Nancy, Brouillette, Marie-Josée, Fellows, Lesley K et al.·Physiotherapy Canada. Physiotherapie Canada·2025

Researchers in this study developed and tested a new questionnaire to measure fatigue severity in people with post-COVID-19 syndrome. The measure, called the PCS Fatigue Severity Measure V1, performed well in their analysis of 414 participants—it correlated strongly with other fatigue measures and distinguished between people still working and those on sick leave. However, this is early-stage research in a single Canadian cohort, and the authors note that further testing in other populations is needed to confirm the measure's reliability over time.

DiagnosticsPost-Exertional Malaise

E2 ModerateBehavioralPEM not requiredCross-Sectional

Post-Traumatic Stress Disorder and Complex Post-Traumatic Stress Disorder in People with Long COVID, ME/CFS, and Controls.

Sanal-Hayes, Nilihan E M, Hayes, Lawrence D, Mclaughlin, Marie et al.·The American journal of medicine·2025

This study compared how often people with long COVID, ME/CFS, and healthy people experience trauma-related mental health conditions. Researchers found that people with long COVID had the highest rates of these conditions (38% combined), followed by people with ME/CFS (20%), while healthy people had none. Both long COVID and ME/CFS groups showed more trauma-related symptoms than controls across multiple measures.

E2 ModerateCohortPEM unclearObservational

Efficacy of vitamin D replacement therapy on 28 cases of myalgic encephalomyelitis/chronic fatigue syndrome after COVID-19 vaccination.

Kodama, Shinichiro, Konishi, Nafuko, Hirai, Yuriko et al.·Nutrition (Burbank, Los Angeles County, Calif.)·2025

This study looked at 28 patients who developed ME/CFS after COVID-19 vaccination and found that most had very low vitamin D levels. When these patients received vitamin D treatment through diet, sun exposure, and supplements, their vitamin D levels improved and their ME/CFS symptoms significantly decreased—with 82% of patients no longer meeting ME/CFS criteria after treatment. Sleep problems and autonomic symptoms (like heart rate and blood pressure changes) showed the most improvement.

E2 ModerateCohortPEM not requiredCross-Sectional

Autonomic Dysfunction and Low Cardio-Respiratory Fitness in Long-Term Post-COVID-19 Syndrome.

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

This study looked at 192 people who had COVID-19 to understand why some develop long-term fatigue and exercise problems. Researchers measured how well the heart adjusts during exercise and found that people with moderate-to-severe post-COVID symptoms had problems with their autonomic nervous system (the system that controls automatic body functions like heart rate). However, these nervous system problems didn't fully explain why patients had lower exercise capacity.

Autonomic Nervous System

E2 ModeratePEM unclearBiobank-Resource

Defining a High-Quality Myalgic Encephalomyelitis/Chronic Fatigue Syndrome cohort in UK Biobank.

Samms, Gemma L, Ponting, Chris P·NIHR open research·2025

This study looked at how ME/CFS is identified in UK Biobank, a large database of health information from hundreds of thousands of people. Researchers found that about 1 in 100 UK Biobank participants had some evidence of ME/CFS, but only about one-third had strong, consistent evidence across multiple records. When they accounted for people too ill to participate in the study, they estimated that around 410,000 people in the UK have ME/CFS.

Diagnostics

E2 ModerateCohortPEM not requiredCross-Sectional

Medical complexity and healthcare utilization among patients attending three U.S. post-COVID clinics.

Nji, Miriam A M, Briones, Elizabeth M, Issa, Anindita et al.·BMC infectious diseases·2025

This study looked at 984 patients who visited specialized clinics for ongoing problems after COVID-19 infection. Patients commonly experienced shortness of breath, fatigue, post-exertional malaise (feeling much worse after activity), and brain fog. Most patients needed multiple medical visits and referrals to different specialists like lung, heart, and neurologists, showing that post-COVID illness is complex and requires coordinated care from many healthcare providers.

Post-Exertional Malaise

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Fatigue, interoplastic and nociplastic distress in myalgic encephalomyelitis/chronic fatigue syndrome, Gulf War Illness, and chronic idiopathic fatigue.

Health outcomes up to 3 years and post-exertional malaise in patients after hospitalization for COVID-19: a multicentre prospective cohort study (CO-FLOW).

A Cross-Sectional Study of Symptom Prevalence, Frequency, Severity, and Impact of Long COVID in Scotland: Part I.

Steroid dynamics in myalgic encephalomyelitis / chronic fatigue syndrome: a case-control study using ultra performance supercritical fluid chromatography tandem mass spectrometry.

Serum Spike Protein Persistence Post COVID Is Not Associated with ME/CFS.

Age-Related Changes in the Clinical Picture of Long COVID.

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

Prospective associations between major depressive disorder, generalized anxiety disorder, fibromyalgia, and myalgic encephalomyelitis/chronic fatigue syndrome.

Wearable technology in the management of complex chronic illness: preliminary survey results on self-reported outcomes.

Immune Signatures in Post-Acute Sequelae of COVID-19 (PASC) and Myalgia/Chronic Fatigue Syndrome (ME/CFS): Insights from the Fecal Microbiome and Serum Cytokine Profiles.

Network structure of functional somatic symptoms.

The relationship between fatigue, sleep quality, and sleep deprivation.

Age-specific alterations of the gut mycobiome in patients with myalgic encephalomyelitis/chronic fatigue syndrome and identification of potential diagnostic biomarkers.

Assessing the Relationship in Symptomology of Myalgic Encephalitis/Chronic Fatigue Syndrome and Long COVID.

Quantifying the Degree of Fatigue in People Reporting Symptoms of Post-COVID-19 Syndrome: Results from a Rasch Analysis.

Post-Traumatic Stress Disorder and Complex Post-Traumatic Stress Disorder in People with Long COVID, ME/CFS, and Controls.

Efficacy of vitamin D replacement therapy on 28 cases of myalgic encephalomyelitis/chronic fatigue syndrome after COVID-19 vaccination.

Autonomic Dysfunction and Low Cardio-Respiratory Fitness in Long-Term Post-COVID-19 Syndrome.

Defining a High-Quality Myalgic Encephalomyelitis/Chronic Fatigue Syndrome cohort in UK Biobank.

Medical complexity and healthcare utilization among patients attending three U.S. post-COVID clinics.

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