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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 6,205 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 →

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404 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

281–300 of 404 studies

E2 ModerateBehavioralPEM unclearCross-Sectional

Sudden vs gradual onset of chronic fatigue syndrome differentiates individuals on cognitive and psychiatric measures.

DeLuca, J, Johnson, S K, Ellis, S P et al.·Journal of psychiatric research·1997

This study looked at whether the way ME/CFS starts—suddenly or gradually—affects thinking abilities and mental health. Researchers tested 36 ME/CFS patients on memory, concentration, and processing speed, and compared them to healthy controls. They found that people whose ME/CFS came on gradually were more likely to have depression or anxiety, while those with sudden onset had more severe memory problems.

Cognitive Impairment

E2 ModerateCohortPEM not requiredCross-Sectional

Patients with chronic fatigue syndrome and accurate feeling-of-knowing judgments.

Lakein, D A, Fantie, B D, Grafman, J et al.·Journal of clinical psychology·1997

Many people with ME/CFS say they have memory problems, but doctors have had trouble proving this in tests. This study looked at whether the issue might be that ME/CFS patients are bad at judging how confident they should be about their memories. When researchers tested both ME/CFS patients and healthy people on a trivia quiz, they found that both groups were equally good at knowing when they probably got an answer right—even though the ME/CFS patients reported much worse fatigue and cognitive symptoms.

Cognitive Impairment

E2 ModerateCohortPEM not requiredCross-Sectional

Cognitive functioning is impaired in patients with chronic fatigue syndrome devoid of psychiatric disease.

DeLuca, J, Johnson, S K, Ellis, S P et al.·Journal of neurology, neurosurgery, and psychiatry·1997

This study tested thinking and memory skills in people with ME/CFS and found they performed worse than healthy people, even among those without depression or anxiety. The cognitive problems—like difficulty concentrating, remembering things, and processing information—appear to be a direct part of ME/CFS itself, not caused by mental health conditions. This suggests the 'brain fog' many ME/CFS patients experience is a real biological feature of the illness.

Cognitive Impairment

E2 ModerateCohortPEM not requiredCross-Sectional

Post-Lyme syndrome and chronic fatigue syndrome. Neuropsychiatric similarities and differences.

Gaudino, E A, Coyle, P K, Krupp, L B·Archives of neurology·1997

This study compared people with ME/CFS and people with post-Lyme syndrome (ongoing fatigue after Lyme disease treatment) to understand how their symptoms differ. Both groups had severe fatigue and trouble thinking clearly, but people with post-Lyme syndrome showed more significant problems with memory, attention, and processing speed than people with ME/CFS. The findings suggest these two conditions may involve different types of brain function problems despite feeling similar to patients.

Cognitive Impairment

E2 ModerateCohortPEM not requiredCross-Sectional

The effects of fatigue on neuropsychological performance in patients with chronic fatigue syndrome, multiple sclerosis, and depression.

Johnson, S K, Lange, G, DeLuca, J et al.·Applied neuropsychology·1997

Researchers tested whether fatigue directly worsens brain performance on a specific attention test (PASAT) in people with ME/CFS, multiple sclerosis, and depression. They found that people with ME/CFS and depression performed worse overall on the test compared to healthy controls, but fatigue itself did not prevent people from improving with practice. This suggests that fatigue may not be the main factor directly causing the thinking difficulties some ME/CFS patients experience.

Cognitive Impairment

E2 ModerateCohortPEM unclearCross-Sectional

Selective impairment of auditory processing in chronic fatigue syndrome: a comparison with multiple sclerosis and healthy controls.

Johnson, S K, DeLuca, J, Diamond, B J et al.·Perceptual and motor skills·1996

This study tested whether people with ME/CFS have trouble processing sounds specifically, or if they struggle with processing information in general. Researchers compared people with ME/CFS, people with multiple sclerosis, and healthy people on two similar tasks—one using sounds and one using visuals. People with ME/CFS performed worse on the sound-based task but did better on the visual task, suggesting their brains may have particular difficulty processing auditory information.

Cognitive Impairment

E2 ModerateCohortPEM not requiredCross-Sectional

Memory, attention, and executive function in chronic fatigue syndrome.

Joyce, E, Blumenthal, S, Wessely, S·Journal of neurology, neurosurgery, and psychiatry·1996

This study compared the thinking abilities of 20 people with ME/CFS to 20 healthy controls using computerized tests and word tasks. Researchers found that ME/CFS patients had difficulty with memory tasks that required effort and attention, especially when they had to actively retrieve or organize information themselves. However, their problems were different from those seen in dementia or stroke-related memory loss, and they performed normally on simpler memory tests.

Cognitive Impairment

E2 ModerateBehavioralPEM not requiredCross-Sectional

Cognitive idiosyncrasies among children with the chronic fatigue syndrome: anomalies in self-reported activity levels.

Fry, A M, Martin, M·Journal of psychosomatic research·1996

This study looked at whether children with ME/CFS and their parents perceive their activity levels differently than healthy children do. Researchers used activity monitors (objective measurement) and asked children and parents to estimate activity (subjective measurement) over 3 days. They found that children with ME/CFS and their parents underestimated how much activity was actually happening, and there was a bigger gap between what they expected to do in the future versus what they wanted to do.

Cognitive Impairment

E2 ModerateCohortPEM not requiredCase-Control

Clinical and neurocognitive features of the post Lyme syndrome.

Bujak, D I, Weinstein, A, Dornbush, R L·The Journal of rheumatology·1996

This study looked at people who had Lyme disease and continued to have fatigue, joint pain, and memory problems even after antibiotic treatment. Researchers compared 23 of these patients to 23 people who recovered fully from Lyme disease. The group with ongoing symptoms performed worse on memory and concentration tests, reported more sleep and mood problems, and showed signs of greater emotional distress.

Cognitive Impairment

E2 ModerateCohortPEM not requiredCross-Sectional

Comparison of 99m Tc HMPAO SPECT scan between chronic fatigue syndrome, major depression and healthy controls: an exploratory study of clinical correlates of regional cerebral blood flow.

Fischler, B, D'Haenen, H, Cluydts, R et al.·Neuropsychobiology·1996

This study used a brain imaging technique called SPECT scans to compare blood flow in the brains of people with ME/CFS, people with depression, and healthy volunteers. Researchers found that in ME/CFS patients, blood flow in the front part of the brain was connected to cognitive problems and physical activity limitations. Unlike depression, ME/CFS did not show overall reduced blood flow in the brain, but did show a specific pattern of asymmetry (one side different from the other) in the side-back regions.

Cognitive Impairment

E2 ModerateCohortPEM not requiredCross-Sectional

Cognitive functioning in patients with chronic fatigue syndrome.

Michiels, V, Cluydts, R, Fischler, B et al.·Journal of clinical and experimental neuropsychology·1996

This study found that people with ME/CFS performed worse than healthy controls on thinking and memory tests. Patients showed slower processing speed, difficulty concentrating, and trouble learning and remembering new information. However, the researchers noted that cognitive problems varied widely between patients, so not everyone with ME/CFS experiences the same level of difficulty.

Cognitive Impairment

E2 ModerateCohortPEM not requiredObservational

Behavioural effects of infectious mononucleosis.

Hall, S R, Smith, A P·Neuropsychobiology·1996

This study looked at how infectious mononucleosis (IM) affects the brain and behavior in both the short and long term. Researchers tested memory, attention, coordination, and mood in people with acute IM, people who had recovered months earlier, and healthy controls. They found that acute IM caused similar brain and behavior problems to the flu, while people recovering from IM months later showed patterns similar to those seen in chronic fatigue syndrome patients.

Cognitive Impairment

E2 ModerateBehavioralPEM not requiredCross-Sectional

A controlled comparison of multiple chemical sensitivities and chronic fatigue syndrome.

Fiedler, N, Kipen, H M, DeLuca, J et al.·Psychosomatic medicine·1996

This study compared people with multiple chemical sensitivities (MCS), chemical sensitivities without a clear trigger (CS), and chronic fatigue syndrome (CFS) to healthy controls. Researchers found that chemically sensitive patients reported more lifestyle disruption and avoided more substances than CFS patients, but all three patient groups had higher rates of psychiatric conditions and unexplained physical symptoms compared to healthy people. Interestingly, standard memory and thinking tests did not show significant differences between groups, suggesting that cognitive problems in these conditions may not show up on typical office-based tests.

Cognitive Impairment

E2 ModerateBehavioralPEM not requiredCross-Sectional

Cognitive functioning and magnetic resonance imaging in chronic fatigue.

Cope, H, Pernet, A, Kendall, B et al.·The British journal of psychiatry : the journal of mental science·1995

This study tested whether people with chronic fatigue have real problems with thinking and memory, or whether these complaints are mainly due to depression and anxiety. Researchers gave cognitive tests and brain scans (MRI) to people with chronic fatigue, people with depression, and healthy controls. They found that people with chronic fatigue performed similarly to controls on objective tests, and brain scans showed no consistent abnormalities. The researchers concluded that complaints of cognitive problems were likely related to mood symptoms rather than physical brain changes.

Cognitive Impairment

E2 ModerateCohortPEM unclearCross-Sectional

Neuropsychological impairments in chronic fatigue syndrome, multiple sclerosis, and depression.

DeLuca, J, Johnson, S K, Beldowicz, D et al.·Journal of neurology, neurosurgery, and psychiatry·1995

This study tested thinking and memory skills in people with ME/CFS, comparing them to people with multiple sclerosis, depression, and healthy individuals. Researchers found that people with ME/CFS had significant trouble processing information quickly, similar to those with depression. The cognitive problems in ME/CFS were not explained by depression or anxiety alone.

Cognitive Impairment

E2 ModerateCohortPEM not requiredCross-Sectional

P300 assessment of chronic fatigue syndrome.

Polich, J, Moore, A P, Wiederhold, M D·Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society·1995

This study measured electrical activity in the brains of people with ME/CFS and healthy controls using a simple listening task where they had to identify specific sounds. Researchers found no differences in brain wave patterns (called P300) between the two groups, even though many ME/CFS patients report problems with memory and attention. This suggests that brain electrical activity measured this way may not be a reliable marker for ME/CFS.

Cognitive Impairment

E2 ModerateBehavioralPEM not requiredCross-Sectional

Dimensional assessment of chronic fatigue syndrome.

Vercoulen, J H, Swanink, C M, Fennis, J F et al.·Journal of psychosomatic research·1994

This study asked 298 people with ME/CFS to fill out detailed questionnaires about how the illness affected them. Researchers found that ME/CFS affects people in nine different ways: mood and emotional health, ability to do daily activities, sleep quality, physical avoidance, thinking and memory problems, beliefs about what caused their illness, relationships and social life, confidence in their own abilities, and overall life satisfaction. Understanding these separate aspects could help doctors better assess and treat ME/CFS in individual patients.

SleepCognitive Impairment

E2 ModerateBehavioralPEM not requiredCross-Sectional

Cognitive functioning in chronic fatigue syndrome and depression: a preliminary comparison.

Schmaling, K B, DiClementi, J D, Cullum, C M et al.·Psychosomatic medicine·1994

Researchers tested thinking and memory skills in 16 people with ME/CFS and 23 people with depression using a brief set of mental tests. Both groups performed similarly to each other and scored in the normal range on most tests. Interestingly, people with ME/CFS reported more cognitive problems than their test scores showed, which the researchers suggest might be due to increased attention to physical sensations rather than actual cognitive damage.

Cognitive Impairment

E2 ModerateBehavioralPEM not requiredCross-Sectional

Psychosocial correlates of illness burden in chronic fatigue syndrome.

Antoni, M H, Brickman, A, Lutgendorf, S et al.·Clinical infectious diseases : an official publication of the Infectious Diseases Society of America·1994

This study looked at how thoughts, feelings, and coping strategies affect how sick ME/CFS patients feel and function day-to-day. Researchers found that negative thinking patterns and avoidance-based coping (like denial) were linked to worse symptoms and lower quality of life, while active problem-solving strategies did not improve outcomes. These relationships held true whether or not patients also had depression.

Cognitive Impairment

E2 ModerateBehavioralPEM not requiredCross-Sectional

Neuropsychology and psychology of MCS.

Fiedler, N, Kipen, H, Deluca, J et al.·Toxicology and industrial health·1994

This study looked at whether people with multiple chemical sensitivities (MCS) and chronic fatigue syndrome (CFS) have psychiatric issues or thinking problems. Researchers found that both groups reported more psychiatric diagnoses than healthy people, and both groups tended to report physical symptoms rather than emotional ones. Surprisingly, the study did not find significant cognitive impairment in MCS patients, except for a small difference in visual memory.

Cognitive Impairment

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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.