Evidence browser

Understanding concussion in myalgic encephalomyelitis/chronic fatigue syndrome: Findings from the 2023 National Health Interview study.

Sirotiak, Zoe, Adamowicz, Jenna L, Thomas, Emily B K·Brain injury·2026

This study found that people with ME/CFS are nearly 5 times more likely to have had a concussion in the past year compared to people without ME/CFS. People with ME/CFS also experienced more falls and dizziness or balance problems. The researchers suggest that doctors should screen patients with ME/CFS more carefully for concussions and take steps to reduce their concussion risk.

E2 ModeratePEM unclearRegistry-Resource

Risk factors for severe post-COVID condition in children, adolescents, and young adults.

Donath, Quirin, Haegele, Matthias, Schindler, Daniela et al.·European journal of pediatrics·2026

This observational study from a German pediatric hospital followed 120 children and young adults with post-COVID condition (PCC), observing that those with more severe illness were more likely to have had 12 or more symptoms during their initial COVID-19 infection, alongside other acute symptoms such as trouble concentrating and fainting-like episodes. One quarter of participants met criteria for ME/CFS, and all of these were in the severely affected group; by analogy, if similar patterns apply to ME/CFS patients, early identification of high-symptom-burden acute illness might help predict who develops severe long-term illness. These findings are preliminary and come from a single hospital site.

Severe MEAutonomic Nervous SystemDiagnosticsCognitive Impairment

Disequilibrium, Rather than Postural Orthostatic Tachycardia Syndrome, Is the Primary Determinant of Orthostatic Intolerance in Patients with Long COVID.

Miwa, Kunihisa·Journal of clinical medicine·2026

Many long COVID patients experience dizziness and difficulty standing (orthostatic intolerance), but researchers found this is not usually caused by the heart racing when standing up (POTS). Instead, balance problems detected by simple standing tests were the main cause in these patients. When treated with an antibiotic or brain stimulation therapy, most patients with balance-related standing problems improved.

Ocular Symptoms in Long COVID: A Cross-Sectional Study.

Kaleem, Shayaan, Sawano, Mitsuaki, Arun, Adith S et al.·Clinical ophthalmology (Auckland, N.Z.)·2026

This study looked at eye problems in people with long COVID, comparing those who developed new eye symptoms (like blurred vision, dry eyes, or floaters) after infection with those who didn't. About 57% of the 595 participants reported new eye symptoms. People with eye symptoms had worse overall health, more financial struggles, and were more likely to have dysautonomia (problems with blood pressure and heart rate control) and ME/CFS.

Shared autonomic phenotype of long COVID and myalgic encephalomyelitis/chronic fatigue syndrome.

Novak, Peter, Systrom, David M, Witte, Alexandra et al.·PloS one·2026

Researchers compared people with Long COVID and ME/CFS to healthy volunteers and found they share very similar patterns of nervous system dysfunction, including problems with blood flow to the brain when standing up, widespread autonomic problems, and nerve damage in the skin. While the two conditions show these striking similarities, the study couldn't identify a single test that clearly separates them from each other, suggesting they may develop through related mechanisms.

E2 ModerateCohortPEM unclearObservational

Testing a Personalised Dysautonomia Management Protocol in Patients with Orthostatic Intolerance and a Diagnosis of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome or Long COVID.

Barr, Julia, Marsden, Lowri, Dassanayake, Theshan et al.·Journal of clinical medicine·2026

This observational study tested whether a personalised 8-week management plan (involving increased fluid and salt intake, pacing strategies, and calf exercises) was feasible and associated with symptom changes in 22 people with ME/CFS or Long COVID who experienced orthostatic intolerance. Reported improvements were modest: autonomic symptom scores improved by 7.7 points, and heart rate response during a standing test decreased slightly; however, adherence was highly variable, and the authors note that statistical improvements may not reflect clinically meaningful symptom relief. The study remains preliminary and cannot establish whether this protocol is an effective treatment.

InterventionsAutonomic Nervous System

Small fiber neuropathy in the post-COVID condition and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Clinical significance and diagnostic challenges.

Azcue, Naiara, Teijeira-Portas, Sara, Tijero-Merino, Beatriz et al.·European journal of neurology·2025

This study found that both long-COVID patients and people with ME/CFS show signs of damage to small nerve fibers in the eyes and altered sensation to heat, compared to healthy people. Researchers used specialized imaging and tests to measure nerve fiber structure and how well patients could detect temperature changes. The findings suggest that small fiber nerve damage may contribute to symptoms like pain and abnormal sensations in these conditions.

Awareness and Perception of Myalgic Encephalomyelitis and Chronic Fatigue Syndrome Among Pain Specialists: A Questionnaire-Based Study.

Uygun, Gürsan Güneş, Gözükızıl, Salim Taner, Bilen, Ayşegül·Cureus·2025

This study asked pain doctors in Turkey about their knowledge of ME/CFS and how they evaluate and treat patients with the condition. The results show that many pain specialists aren't familiar with ME/CFS, and some hold misconceptions—like thinking it's a type of depression or that intense exercise will help. This matters because pain doctors could potentially help ME/CFS patients, but they need better education about the condition first.

E2 ModerateCohortPEM not requiredCase-Control

Diagnosis of chronic fatigue syndrome using beat-to-beat autonomic measurements.

Kujawski, Sławomir, Tabisz, Hanna, Morten, Karl J et al.·Journal of translational medicine·2025

Researchers used artificial intelligence to analyze how the heart and nervous system behave differently in ME/CFS patients compared to healthy people. By measuring heart rate changes beat-by-beat, they found a pattern that could identify ME/CFS patients with 89% accuracy. The key differences included a less responsive vagal nerve (which normally calms the body), a more active stress response in blood vessels, and less efficient heart pumping.

E2 ModerateCohortPEM requiredObservational

Low Vasopressin in Myalgic Encephalomyelitise/Chronic Fatigue Syndrome.

Huhmar, Helena M, Soinne, Lauri S, Bertilson, Bo Christer et al.·Endocrine practice : official journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists·2025

This study found that most people with ME/CFS have abnormally low levels of vasopressin, a hormone that helps your body control water balance and blood volume. The researchers measured this hormone and fluid markers in over 100 ME/CFS patients and discovered that 82% had vasopressin levels below the detectable range. This may help explain why many ME/CFS patients experience excessive thirst, frequent urination, and dizziness when standing up.

The Relationship Between Hemodynamic Responses During Head-Up Tilt Testing and Parameters of Infection in Post-COVID Syndrome, Chronic Fatigue Syndrome, and Late-Stage Lyme Disease.

Milovanovic, Branislav, Markovic, Nikola, Petrovic, Masa et al.·Viruses·2025

This study examined 1036 patients with post-COVID syndrome, chronic fatigue syndrome, and Lyme disease to understand why they experience dizziness and fainting when standing up. Researchers performed tilt-table tests (where patients lie on a table that tilts upward) and checked for signs of past or ongoing infections through blood tests. They found that patients with evidence of multiple past infections were more likely to have abnormal responses during the tilt test, suggesting that lingering effects from infections may affect the nervous system's ability to control blood pressure and heart rate.

E2 ModerateCohortPEM unclearObservational

Autonomic Dysfunction in Patients with Acute Infection with Coxiella burnetii.

Milovanović, Branislav, Marković, Nikola, Ristanović, Elizabeta et al.·Pathogens (Basel, Switzerland)·2025

This study looked at how the autonomic nervous system (the part that controls heart rate, blood pressure, and other automatic body functions) works in people who had acute infection with Coxiella burnetii, a bacterium that causes Q fever. Researchers tested 100 infected patients and 56 healthy controls using heart monitoring tests and found that infected patients had more problems with autonomic control, particularly in how their bodies regulate heart rate and blood pressure. These findings suggest that this infection might trigger lasting problems with the autonomic nervous system that could contribute to ME/CFS symptoms.

Autonomic Dysfunction in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): Findings from the Multi-Site Clinical Assessment of ME/CFS (MCAM) Study in the USA.

Issa, Anindita, Lin, Jin-Mann S, Chen, Yang et al.·Journal of clinical medicine·2025

This study found that people with ME/CFS experience much higher levels of autonomic nervous system problems—which control things like heart rate, blood pressure, and digestion—compared to healthy people. Nearly all ME/CFS patients (97%) had at least one autonomic symptom, with common complaints including dizziness, cold hands and feet, and difficulty standing up. The more autonomic symptoms someone had, especially in certain areas like blood pressure regulation and stomach problems, the more severe their overall illness tended to be.

E2 ModerateCohortPEM not requiredObservational

Nonpelvic comorbid symptoms of 45 patients with pain of pelvic venous origin, before and after treatment.

Smith, Steven J, Smith, B Holly, Sichlau, Michael J et al.·Phlebology·2025

This study looked at 45 women with chronic pelvic pain caused by abnormal blood pooling in pelvic veins. These patients experienced many symptoms beyond pelvic pain—including brain fog, fatigue, migraines, constipation, and anxiety. After receiving a catheter-based procedure to fix the blood pooling, most of these systemic symptoms improved significantly (by 50% or more).

Pain and SensitizationAutonomic Nervous SystemCognitive Impairment

Cross-Sectional Study Evaluating the Role of Autonomic Nervous System Functional Diagnostics in Differentiating Post-Infectious Syndromes: Post-COVID Syndrome, Chronic Fatigue Syndrome, and Lyme Disease.

Milovanovic, Branislav, Markovic, Nikola, Petrovic, Masa et al.·Biomedicines·2025

This study compared how the nervous system functions differently in people with Post-COVID syndrome, ME/CFS (both COVID-related and unrelated), and late-stage Lyme disease—three conditions that often feel similar but may have different causes. Researchers tested 758 patients using heart rhythm monitors, tilt tests, and blood pressure measurements to see how their bodies responded to position changes and stress. They found that Lyme disease patients showed a distinct pattern of nerve dysfunction (adrenergic failure), while Post-COVID and ME/CFS patients had different types of nervous system imbalances.

Autonomic Nervous SystemDiagnostics

The Diagnostic Journey of Dysautonomia Patients: Insights from a Patient-Reported Outcome Study.

O'Dell, John A, Walker, Ash, Latham, Andrew J et al.·Journal of patient experience·2025

This study followed 672 adults with dysautonomia (a condition where the nervous system that controls automatic body functions doesn't work properly) to understand how long it takes to get diagnosed and which doctors help with diagnosis. On average, it took 7.7 years for people to receive a diagnosis, and they often saw multiple types of doctors before getting answers. The study found that dysautonomia commonly occurs alongside other conditions like Ehlers-Danlos syndrome, mast cell disorders, and ME/CFS, which can make diagnosis even more confusing.

Autonomic Nervous SystemCognitive Impairment

Characterization of Postural Orthostatic Tachycardia Syndrome in Long COVID: Self-reported Data From the LISTEN Study.

Al Mouslmani, Mohammad, Sawano, Mitsuaki, Arun, Adith S et al.·JACC. Advances·2025

This study looked at people with long COVID who also developed POTS (a condition where the heart rate spikes when standing up). Among nearly 600 long COVID patients, about 29% reported having POTS. People with both conditions reported significantly more symptoms—including dizziness, chest pain, extreme fatigue, difficulty exercising, and brain fog—and experienced worse overall health and quality of life compared to those with long COVID alone.

Assessment of Autonomic Nervous System Function in Patients with Chronic Fatigue Syndrome and Post-COVID-19 Syndrome Presenting with Recurrent Syncope.

Milovanovic, Branislav, Markovic, Nikola, Petrovic, Masa et al.·Journal of clinical medicine·2025

This study examined how the autonomic nervous system (the part that controls heart rate, blood pressure, and other automatic functions) works differently in people with ME/CFS compared to healthy people. Researchers tested 440 people, including those with ME/CFS from unknown causes and those whose ME/CFS developed after COVID-19, using heart and blood pressure monitoring tests. They found that both ME/CFS groups had significant problems with autonomic function and experienced fainting or near-fainting episodes at high rates, though the post-COVID group showed somewhat different patterns.

E2 ModerateCohortPEM unclearObservational

The Relation Between Cardiac Output and Cerebral Blood Flow in ME/CFS Patients with a POTS Response During a Tilt Test.

van Campen, C Linda M C, Visser, Frans C·Journal of clinical medicine·2025

When people with ME/CFS and POTS stand up, their blood pressure and heart rate don't respond normally, causing symptoms like dizziness and fatigue. This study looked at 260 ME/CFS patients during a tilt test to understand how the heart's output of blood relates to blood flow in the brain. The researchers found two different patterns: about two-thirds of patients showed their brain blood flow dropped at roughly the same rate as their heart's output decreased, while about one-third had a different pattern where their heart was racing but their heart output wasn't dropping as much, and their brain blood flow didn't follow the expected pattern.