Skip to content

Start Here
Atlas
Evidence
Research
Ask
Updates
About
Support

Evidence Atlas

ME/CFS Atlas — A public knowledge atlas for ME/CFS

Start Here
Atlas
Evidence
Research
Ask
FAQ
Glossary
Updates
Methodology
Press
Retractions
Contribute
About
Support
Contact

Weekly research digest — no spam

ME/CFS Atlas is an evidence reference platform, not a medical provider. Content is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.

Generator v1·Scanner v1.4·Lint gate: enforce·See methodology

© 2026 ME/CFS Atlas

ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

Evidence browser

Search and filter 6,205 studies by evidence level, diagnostic criteria, PEM status, and research domain. Each entry links to the original source.

Studies sorted by evidence level, then year. Browse by topic instead →

Evidence level (E0–E3) reflects study type and replication, not methodological quality. A weak systematic review still sits at E0. How evidence levels work →

Sort

533 studies

E0 — Consensus654E1 — Replicated321E2 — Moderate2,807E3 — Preliminary2,423

ME/CFS4,040Long COVID224Post-infectious190Overlapping1,064

Required for diagnosis417Not specified / unclear2,251Not required3,537

Post-Exertional Malaise1,082Cognitive Dysfunction1,749Pain1,628Unrefreshing Sleep805Orthostatic Intolerance484

Cytokines821Gene Expression573Metabolomics477Neuroimaging472Autoantibodies460

Infection-Triggered1,182Long COVID Overlap604Pediatric496Severe232

Strong Phenotyping445Sex-Stratified330Severe ME Included119

Systematic Review272Meta-Analysis61RCT301

Peer-reviewed6,148Preprint3Unclear54

401–420 of 533 studies

E3 PreliminaryReviewPEM unclearReview-Narrative

Explanatory and pragmatic perspectives regarding idiopathic physical symptoms and related syndromes.

Engel, Charles C·CNS spectrums·2006

This paper discusses two different ways to approach studying and treating illnesses like ME/CFS that don't have a clear, well-understood cause. One approach focuses on finding the root cause in controlled settings; the other focuses on whether treatments actually work in real-world patient care. The authors argue that for conditions like ME/CFS, the practical approach—focusing on what helps patients in everyday life—may be more useful than searching for a single underlying cause.

E3 PreliminaryCommentaryPEM not requiredEditorial

Challenges for molecular profiling of chronic fatigue syndrome.

Vernon, Suzanne D, Whistler, Toni, Aslakson, Eric et al.·Pharmacogenomics·2006

This paper discusses why it's been difficult for scientists to find reliable blood tests (biomarkers) to diagnose ME/CFS and develop treatments. The authors explain that ME/CFS is complex because it affects many body systems at once, and each researcher may focus on different areas based on their expertise. They suggest that blood tests show promise for understanding ME/CFS and that combining genetic information, protein data, and information about patients' environments and behaviors could help researchers better understand why different patients experience the illness differently.

E3 PreliminaryDiagnosticPEM not requiredMethods-Paper

Brief and distinct empirical sleepiness and fatigue scales.

Bailes, Sally, Libman, Eva, Baltzan, Marc et al.·Journal of psychosomatic research·2006

Doctors and patients often use the words 'sleepiness' and 'fatigue' interchangeably, but they actually describe different experiences. This study created two short, separate questionnaires—one to measure sleepiness (the urge to sleep) and one to measure fatigue (overall exhaustion)—by pulling items from existing popular fatigue and sleepiness scales. Testing these new scales on people with ME/CFS, narcolepsy, and healthy controls showed they measure distinct conditions that may respond to different treatments.

SleepDiagnostics

E3 PreliminaryReviewPEM unclearReview-Narrative

Conceptual issues in undifferentiated somatoform disorder and chronic fatigue syndrome.

van Staden, Werdie C W·Current opinion in psychiatry·2006

This paper examines why it can be difficult to distinguish between two conditions that both cause severe tiredness: undifferentiated somatoform disorder (a condition where physical symptoms occur without clear medical causes) and ME/CFS. The author argues that a key difference may be how patients experience their fatigue—some describe it as purely physical rather than mental—and that this distinction has not been properly studied or recognized in ME/CFS research.

E3 PreliminaryDiagnosticPEM not requiredMethods-Paper

Improving the diagnostic criteria and procedures for chronic fatigue syndrome.

King, Caroline, Jason, Leonard A·Biological psychology·2005

Doctors have used different definitions to diagnose ME/CFS since 1988, but these definitions were never tested scientifically to see if they actually work well. This study compared 15 people with ME/CFS, 15 with depression, and 15 healthy people to find better ways to diagnose ME/CFS. The researchers found that adding new symptoms, measuring how severe symptoms are, and using specific tests could help doctors diagnose ME/CFS more accurately.

E3 PreliminaryDiagnosticPEM not requiredMethods-Paper

Psychometric properties of the CDC Symptom Inventory for assessment of chronic fatigue syndrome.

Wagner, Dieter, Nisenbaum, Rosane, Heim, Christine et al.·Population health metrics·2005

Researchers created and tested a new questionnaire called the CDC CFS Symptom Inventory to help measure the many different symptoms that people with ME/CFS experience—not just fatigue, but also other important symptoms like problems with memory, sleep, and pain. They gave this questionnaire to 164 people (some with ME/CFS, some with other illnesses, and some without fatigue) and found that the questionnaire reliably distinguished people with ME/CFS from others and worked well when compared to existing fatigue measurement tools.

E3 PreliminaryReviewPEM unclearReview-Narrative

[Diagnosing asthenia and chronic fatigue syndrome].

Aslangul, Elisabeth, Le Jeunne, Claire·La Revue du praticien·2005

This article discusses how doctors can distinguish between general tiredness (asthenia) and ME/CFS, which is a serious long-term illness characterized by severe fatigue that doesn't improve with rest. The authors review the clinical features and diagnostic approaches that help healthcare providers identify ME/CFS in their patients. Understanding these differences is important so patients receive appropriate diagnosis and care.

E3 PreliminaryReviewPEM unclearReview-Narrative

[Chronic fatigue syndrome: a syndrome in search of definition].

Sánchez Rodríguez, A, González Maroño, C, Sánchez Ledesma, M·Revista clinica espanola·2005

This review examines how ME/CFS is defined and understood in clinical practice. The authors discuss the challenges doctors face in recognizing and diagnosing this condition, since it affects different people in different ways. The study highlights why having clear, consistent definitions is essential for helping patients get proper care and advancing research.

E3 PreliminaryCohortPEM unclearCross-Sectional

Urinary electrophoretic profiles from chronic fatigue syndrome and chronic fatigue syndrome/fibromyalgia patients: a pilot study for achieving their normalization.

Casado, Begoña, Zanone, Chiara, Annovazzi, Laura et al.·Journal of chromatography. B, Analytical technologies in the biomedical and life sciences·2005

Researchers collected urine samples from people with ME/CFS, people with ME/CFS plus fibromyalgia, and healthy controls to look for chemical differences. Using a specialized lab technique called electrophoresis, they found that the urine samples from people with these conditions showed distinct patterns of chemicals compared to healthy people. These patterns might potentially be used as biological markers to help identify and understand these illnesses.

E3 PreliminaryReviewPEM not requiredReview-Narrative

[Chronic fatigue syndrome: its importance in occupational medicine].

Wiszniewska, Marta, Walusiak, Jolanta, Wittczak, Tomasz et al.·Medycyna pracy·2005

This paper reviews what we know about ME/CFS, including what causes it, how it presents in patients, and how doctors can diagnose it. Since extreme tiredness appears in many different health conditions—both physical and mental—the authors explain how doctors can tell ME/CFS apart from other illnesses. The paper also covers treatment approaches and emphasizes why occupational health doctors need to understand ME/CFS to protect workers' health.

E3 PreliminaryReviewPEM not requiredReview-Narrative

Unloading the trunk: neurasthenia, CFS and race.

Luthra, A, Wessely, S·Social science & medicine (1982)·2004

This study examines how ME/CFS and its historical predecessor neurasthenia have been discussed in terms of race and ethnicity over the past century. The authors found that there is a pattern of thinking that associates fatigue illnesses with technological 'development' in white countries, and they explore why far fewer non-white patients appear in specialist ME/CFS clinics compared to what you might expect from the general population.

E3 PreliminaryReviewPEM unclearReview-Narrative

Patient activism and the struggle for diagnosis: Gulf War illnesses and other medically unexplained physical symptoms in the US.

Zavestoski, Stephen, Brown, Phil, McCormick, Sabrina et al.·Social science & medicine (1982)·2004

This study looks at how Gulf War veterans and patients with conditions like ME/CFS, fibromyalgia, and chemical sensitivity have struggled to get their illnesses recognized as real by doctors. The researchers found that getting a diagnosis depends on several factors: whether the medical community accepts the diagnosis, whether patients themselves believe in it, how much uncertainty exists about what causes it, and how organized patients are in pushing for recognition. The authors suggest that doctors may need to accept that some illnesses may not have a clear cause, and that listening to what patients experience is just as important as finding a cause.

E3 PreliminaryReviewPEM not requiredReview-Narrative

Myasthenia gravis: diagnostic mimics.

Engstrom, John W·Seminars in neurology·2004

This paper helps doctors tell the difference between myasthenia gravis (MG) and other conditions that look similar. MG causes muscle weakness that comes and goes, especially in the eyes and face. The authors review many other diseases—including neurological problems, infections, and other conditions—that can be mistaken for MG but are actually something else.

E3 PreliminaryReviewPEM unclearReview-Narrative

Evaluation and management of medically unexplained physical symptoms.

Richardson, Ralph D, Engel, Charles C·The neurologist·2004

This article reviews research on medically unexplained physical symptoms (MUPS)—symptoms that persist without clear diagnosis. The authors note that conditions like ME/CFS, fibromyalgia, and others may be more similar than different, and suggest that helpful treatment involves working closely with doctors to gradually increase activity and develop healthy coping strategies rather than relying only on medications.

E3 PreliminaryReviewPEM unclearReview-Narrative

The concepts of fatigue and depression in cancer.

Reuter, K, Härter, M·European journal of cancer care·2004

This paper examines why fatigue and depression often occur together in cancer patients and look so similar. The authors compare the symptoms of fatigue and depression to see what's the same and what's different, finding that while they share many symptoms, depression has specific psychological features that fatigue doesn't. They suggest that better tools are needed to help doctors tell the two conditions apart.

E3 PreliminaryCommentaryPEM not requiredEditorial

New insights into culture driven disorders.

Aceves-Avila, Francisco Javier, Ferrari, Robert, Ramos-Remus, Cesar·Best practice & research. Clinical rheumatology·2004

This editorial examines why conditions like ME/CFS, fibromyalgia, and similar illnesses are often difficult for doctors to diagnose using standard tests. The authors suggest that social and cultural factors—including how society views these diseases and how disability systems work—play a major role in how these illnesses show up in patients. They argue that understanding these broader influences could help doctors offer better support to patients.

E3 PreliminaryPEM not required

[Appraisal of Lyme borreliosis].

Hausotter, W·Versicherungsmedizin·2004

Lyme disease is an infection spread by tick bites that can cause many different symptoms affecting multiple body systems. This article discusses how doctors can better identify and diagnose Lyme disease, especially since its symptoms overlap with conditions like fibromyalgia and chronic fatigue syndrome. People who work outdoors in areas where Lyme disease is common face higher infection risks and may qualify for financial compensation if diagnosed.

E3 PreliminaryCommentaryPEM not requiredEditorial

Identification of masqueraders of autoimmune disease in the office.

Frieri, Marianne·Allergy and asthma proceedings·2003

This article discusses how several autoimmune and rheumatologic diseases can look like allergies or other conditions, making them easy to miss in a doctor's office. The author reviews nine conditions—including ME/CFS and fibromyalgia—that are often confused with other illnesses and explains how doctors can use blood tests and other tools to correctly identify them.

E3 PreliminaryGuidelinePEM not requiredEditorial

An approach to chronic fatigue syndrome in adults.

Sabin, Thomas D·The neurologist·2003

This paper helps doctors, especially neurologists, understand how to properly evaluate patients who are experiencing severe fatigue. The author emphasizes that while ME/CFS is a real condition, it's important to rule out other medical problems that can cause similar symptoms before confirming an ME/CFS diagnosis. Since there is no blood test or scan that can definitively diagnose ME/CFS, careful evaluation and questioning of patients is essential.

E3 PreliminaryReviewPEM unclearReview-Narrative

Chronic fatigue syndrome. An overview of current concepts.

Aktan, Nadine M·Advance for nurse practitioners·2003

This is an overview article that explains what doctors and nurses understand about chronic fatigue syndrome (ME/CFS) based on current medical knowledge. The article reviews existing concepts and ideas about the condition rather than presenting new research data. It was written to help healthcare providers, particularly nurse practitioners, better understand and care for patients with ME/CFS.

← Previous Next 20 studies →

Or browse by topic

PEM Immune Neuro Metabolic Biomarkers Severe ME Long COVID Cognitive

Curated Collections

Thematic groupings by clinical question or research area.

Neuroinflammation Evidence

PET imaging and other studies providing evidence for brain inflammation in ME/CFS.

Metabolism & Mitochondria

Metabolomics and mitochondrial function studies revealing energy metabolism disruption.

Biomarkers

Studies identifying potential biological markers for ME/CFS diagnosis and stratification.

PEM-Specific Research

Studies specifically examining post-exertional malaise, the hallmark symptom of ME/CFS.