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

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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.

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ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

Evidence browser

Search and filter 6,119 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 →

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380 studies

E0 — Consensus628E1 — Replicated319E2 — Moderate2,756E3 — Preliminary2,416

ME/CFS4,009Long COVID207Post-infectious188Overlapping1,031

Required for diagnosis409Not specified / unclear2,190Not required3,520

Post-Exertional Malaise1,039Cognitive Dysfunction1,711Pain1,606Unrefreshing Sleep786Orthostatic Intolerance470

Cytokines812Gene Expression564Metabolomics469Neuroimaging464Autoantibodies454

Infection-Triggered1,157Long COVID Overlap563Pediatric494Severe227

Strong Phenotyping427Sex-Stratified325Severe ME Included115

Systematic Review256Meta-Analysis59RCT299

Peer-reviewed6,062Preprint3Unclear54

361–380 of 380 studies

E3 PreliminaryCommentaryPEM not requiredEditorial

Psychomotor speed: possibly a new marker for overtraining syndrome.

Nederhof, Esther, Lemmink, Koen A P M, Visscher, Chris et al.·Sports medicine (Auckland, N.Z.)·2006

This 2006 review proposes that psychomotor speed—how quickly people can process and respond to information—might be a useful early marker for overtraining syndrome in athletes. The authors observed that slowness in psychomotor speed is consistently reported in both chronic fatigue syndrome and major depression, and they hypothesise it could also appear in overtraining. However, this is a theoretical proposal awaiting empirical testing in athletes with overtraining.

Cognitive Impairment

E3 PreliminaryCohortPEM unclearCase-Control

Efficacy of neurotropin in chronic fatigue syndrome: a case report.

Toda, Katsuhiro, Kimura, Hiroaki·Hiroshima journal of medical sciences·2006

This case report describes one 28-year-old man with ME/CFS who was treated with a medication called Neurotropin (four tablets daily). His fatigue and widespread pain began improving within a week, and his sleep, focus, and memory improved within two weeks. He stopped taking the medication after 11 weeks and remained symptom-free for at least 5 months afterward.

Pain and SensitizationSleepCognitive Impairment

E3 PreliminaryDiagnosticPEM not requiredMethods-Paper

Exploration of statistical dependence between illness parameters using the entropy correlation coefficient.

Craddock, R Cameron, Taylor, Renee, Broderick, Gordon et al.·Pharmacogenomics·2006

Researchers tested a new statistical method called the entropy correlation coefficient to identify which ME/CFS symptoms and test results are related to each other. They studied 130 women and found that fatigue-related measures were strongly connected to each other, as were general quality-of-life measures and depression scores. Importantly, they discovered some relationships between cognitive test results and ME/CFS that hadn't been found with traditional statistical methods.

Cognitive Impairment

E3 PreliminaryMechanismPEM not requiredCross-Sectional

Objective evidence of cognitive complaints in Chronic Fatigue Syndrome: a BOLD fMRI study of verbal working memory.

Lange, G, Steffener, J, Cook, D B et al.·NeuroImage·2005

This study used brain imaging to see what happens when people with ME/CFS listen to complex spoken information. Researchers found that people with ME/CFS could understand the information just as well as healthy people, but their brains had to work much harder to do it—using more brain regions and requiring greater effort. This provides scientific proof that the thinking and concentration difficulties ME/CFS patients report are real and visible on brain scans.

Cognitive Impairment

E3 PreliminaryCohortPEM not requiredObservational

Neuropsychiatric sequelae of Nipah virus encephalitis.

Ng, Beng-Yeong, Lim, C C Tchoyoson, Yeoh, Alice et al.·The Journal of neuropsychiatry and clinical neurosciences·2004

This study followed 9 people who had Nipah virus brain inflammation for 2 years to see what happened to them afterward. Most developed psychiatric symptoms like depression or personality changes, and nearly all showed memory and attention problems. Interestingly, two patients developed chronic fatigue syndrome after their initial illness recovered.

Cognitive Impairment

E3 PreliminaryReviewPEM not requiredReview-Narrative

Subjective health complaints, sensitization, and sustained cognitive activation (stress).

Eriksen, H R, Ursin, H·Journal of psychosomatic research·2004

This review suggests that common symptoms like pain, tiredness, sleep problems, and digestive issues in conditions like ME/CFS may occur when the body's normal sensing system becomes overly sensitive. Rather than being caused by hidden disease, these symptoms may develop when people experience sustained stress and feel helpless, causing the nervous system to amplify normal bodily signals until they become unbearable.

Cognitive ImpairmentPain and Sensitization

E3 PreliminaryMechanismPEM not requiredObservational

Learning and memorization impairment in childhood chronic fatigue syndrome manifesting as school phobia in Japan.

Miike, Teruhisa, Tomoda, Akemi, Jhodoi, Takako et al.·Brain & development·2004

This study followed children with chronic fatigue syndrome (CFS) in Japan over 15 years to understand why they experience severe tiredness and difficulty learning and remembering information. The researchers found that these children had problems with their autonomic nervous system (the automatic system controlling heart rate, temperature, and digestion), disrupted sleep-wake cycles similar to jet lag, and reduced blood flow to certain brain areas. Understanding these patterns may help explain why learning becomes so difficult for children with CFS.

Cognitive ImpairmentSleep

E3 PreliminaryMechanismPEM not requiredCross-Sectional

Single-photon emission computerized tomography and neurocognitive function in patients with chronic fatigue syndrome.

Schmaling, Karen B, Lewis, David H, Fiedelak, Jessica I et al.·Psychosomatic medicine·2003

Researchers used brain imaging scans to compare how the brains of people with ME/CFS and healthy people work during a challenging listening and memory task. People with ME/CFS performed just as well on the task as healthy people, but reported feeling like they had to work much harder mentally. The brain scans showed that people with ME/CFS had a different pattern of brain activity—more spread out rather than focused in specific areas—suggesting their brains may be working less efficiently.

Cognitive Impairment

E3 PreliminaryReviewPEM unclearReview-Narrative

Cognitive and mood disturbance as causes and symptoms of fatigue in cancer patients.

Valentine, A D, Meyers, C A·Cancer·2001

This review discusses how fatigue, brain fog, and depression are connected in cancer patients and how they may cause or worsen each other. The authors suggest that understanding these connections might help doctors develop better, more personalized treatments that address the specific needs of each patient.

Cognitive Impairment

E3 PreliminaryBehavioralPEM not requiredCase-Control

Treatment of chronic fatigue with neurofeedback and self-hypnosis.

Hammond, D C·NeuroRehabilitation·2001

This study describes one young woman with ME/CFS whose main problem was brain fog and difficulty thinking clearly. Doctors found an abnormal brain wave pattern on her EEG scan and treated her with two techniques: neurofeedback (training to change brain wave patterns) and self-hypnosis. She felt significantly better, with improvements in fatigue and mental clarity that lasted for at least 9 months.

Cognitive Impairment

E3 PreliminaryMechanismPEM not requiredCross-Sectional

Cortical motor potential alterations in chronic fatigue syndrome.

Gordon, R, Michalewski, H J, Nguyen, T et al.·International journal of molecular medicine·1999

Researchers measured electrical brain activity in people with ME/CFS while they performed tasks like responding to targets, remembering information, and moving on command. They found that people with ME/CFS were slower at these tasks and showed weaker brain signals before moving, suggesting their brains may prepare for movement differently. However, their brains processed sensory information and made decisions normally.

Cognitive Impairment

E3 PreliminaryReviewPEM not requiredReview-Narrative

Parallels between post-polio fatigue and chronic fatigue syndrome: a common pathophysiology?

Bruno, R L, Creange, S J, Frick, N M·The American journal of medicine·1998

This review examines similarities between fatigue experienced by polio survivors and people with ME/CFS, suggesting they may share common underlying brain problems. Both conditions involve difficulty concentrating, staying awake, and severe fatigue. The researchers propose that reduced dopamine (a brain chemical) and problems with specific brain systems might explain fatigue in both diseases.

Cognitive Impairment

E3 PreliminaryReviewPEM not requiredReview-Narrative

Research on cognitive complaints and cognitive functioning in patients with chronic fatigue syndrome (CFS): What conclusions can we draw?

Wearden, A J, Appleby, L·Journal of psychosomatic research·1996

People with ME/CFS often report problems with memory and concentration, but when researchers test their cognitive abilities in the lab, they don't find major deficits. This review suggests the gap between what patients experience and what tests show might be because lab tests don't measure 'real-world' thinking very well. In ME/CFS, everyday mental tasks may be using up so much energy that patients have less mental flexibility left over for other things.

Cognitive Impairment

E3 PreliminaryBehavioralPEM not requiredCase-Control

EEG biofeedback as a treatment for chronic fatigue syndrome: a controlled case report.

James, L C, Folen, R A·Behavioral medicine (Washington, D.C.)·1996

This study tested whether a brain training technique called EEG neurofeedback could help a person with chronic fatigue syndrome (CFS). The patient received this treatment and was tested before and after using standard cognitive (thinking) tests. The results showed improvements in memory, thinking skills, daily functioning, and overall quality of life.

Cognitive Impairment

E3 PreliminaryReviewPEM not requiredReview-Narrative

Cognitive functioning of patients with chronic fatigue syndrome.

Johnson, S K, DeLuca, J, Fiedler, N et al.·Clinical infectious diseases : an official publication of the Infectious Diseases Society of America·1994

Many people with ME/CFS experience brain fog and difficulty thinking clearly, which can be just as disabling as physical symptoms. This review examined research on these cognitive problems and found that the issue may not be with memory itself, but rather with how the brain processes information—like a computer that struggles to handle incoming data quickly enough. Understanding this difference is important for developing better treatments and support strategies.

Cognitive Impairment

E3 PreliminaryReviewPEM not requiredReview-Narrative

Neuropsychiatric status of patients with chronic fatigue syndrome: an overview.

Deluca, J, Johnson, S K, Natelson, B H·Toxicology and industrial health·1994

This review examines how ME/CFS affects thinking, memory, and mental health. Researchers compared people with ME/CFS to people with multiple sclerosis, depression, and healthy individuals to understand the neuropsychiatric symptoms (brain and mental health effects) that often accompany the chronic fatigue. The study suggests that cognitive problems in ME/CFS are a real biological feature of the illness, not simply depression.

Cognitive Impairment

E3 PreliminaryCohortPEM not requiredCross-Sectional

Analysis of neuropsychological functioning in patients with chronic fatigue syndrome.

Grafman, J, Schwartz, V, Dale, J K et al.·Journal of neurology, neurosurgery, and psychiatry·1993

This study tested memory and thinking skills in 20 people with ME/CFS who reported memory problems. The researchers found that patients did have mild difficulty with memory tasks that required deep thinking and organization of information, but performed normally on other types of memory tests. Importantly, the severity of fatigue and other physical findings did not predict how well people performed on memory tests.

Cognitive Impairment

E3 PreliminaryReviewPEM not requiredReview-Narrative

Chronic fatigue syndrome and the psychiatrist.

Abbey, S E, Garfinkel, P E·Canadian journal of psychiatry. Revue canadienne de psychiatrie·1990

This review article examines ME/CFS and the role psychiatrists can play in caring for patients. The authors note that ME/CFS involves thinking difficulties, mood changes, and behavioral symptoms alongside fatigue. They explain what psychiatrists should know about the condition and how they can help in assessment and treatment.

Cognitive Impairment

E3 PreliminaryBehavioralPEM unclearCross-Sectional

The neuropsychological dimensions of postinfectious neuromyasthenia (chronic fatigue syndrome): a preliminary report.

Altay, H T, Toner, B B, Brooker, H et al.·International journal of psychiatry in medicine·1990

This study looked at whether ME/CFS patients who reported memory and concentration problems actually showed these difficulties when tested. Surprisingly, the patients performed better than average on standard cognitive tests, even though they felt they had cognitive problems. The researchers suggested that psychological factors might explain why patients' subjective experience didn't match their test results.

Cognitive Impairment

E3 PreliminaryMechanismPEM unclearObservational

Sensory and cognitive event-related potentials in myalgic encephalomyelitis.

Prasher, D, Smith, A, Findley, L·Journal of neurology, neurosurgery, and psychiatry·1990

This study tested whether ME/CFS patients have objective brain activity differences related to thinking and attention. Researchers used special sensors to measure how the brain responds to sounds and tasks requiring concentration. While basic sensory responses were normal, they found that brain signals related to attention and processing speed were slower in about one-third to one-half of patients tested, suggesting ME/CFS affects how the brain handles information rather than basic sensation.

Cognitive Impairment

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.