Evidence browser

Complement Component C1q as a Potential Diagnostic Tool for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Subtyping.

Castro-Marrero, Jesús, Zacares, Mario, Almenar-Pérez, Eloy et al.·Journal of clinical medicine·2021

Researchers analyzed blood samples from 250 women with ME/CFS to see if specific blood markers could help identify different types of the disease. They found that about 43% of participants had high levels of a protein called C1q, which was particularly associated with those experiencing more pain symptoms. This discovery suggests that blood tests might one day help doctors identify which ME/CFS patients belong to which subgroup, potentially leading to better tailored treatments.

Immune System

Homebound versus Bedridden Status among Those with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Conroy, Karl, Bhatia, Shaun, Islam, Mohammed et al.·Healthcare (Basel, Switzerland)·2021

This study looked at over 2,100 people with ME/CFS to understand different levels of severity, focusing on those who are homebound (unable to leave home) and bedridden (unable to leave bed). The researchers found that people who are bedridden experience post-exertional malaise (PEM)—a worsening of symptoms after physical or mental activity—differently or more severely than those who are only homebound. This research helps doctors and patients better understand how severe ME/CFS can become.

Patients with Persistent Polyclonal B-Cell Lymphocytosis Share the Symptomatic Criteria of Systemic Exertion Intolerance Disease.

Morizot, Romain, de Korwin, Jean-Dominique, Feugier, Pierre et al.·Journal of clinical medicine·2021

Researchers studied a rare blood condition called persistent polyclonal B-cell lymphocytosis (PPBL) and found that most patients with PPBL experience symptoms very similar to ME/CFS, including severe fatigue that doesn't improve with rest, worsening after physical activity, sleep problems, and difficulty thinking clearly. Out of 39 patients surveyed, 72% met the official criteria for ME/CFS, and nearly all reported chronic fatigue lasting more than 6 months. This finding suggests these two conditions may share common underlying features, though more research is needed to understand why.

Autoantibodies to Vasoregulative G-Protein-Coupled Receptors Correlate with Symptom Severity, Autonomic Dysfunction and Disability in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.

Freitag, Helma, Szklarski, Marvin, Lorenz, Sebastian et al.·Journal of clinical medicine·2021

This study examined whether certain antibodies in ME/CFS patients' blood relate to how severe their symptoms are. The researchers tested 116 ME/CFS patients for antibodies that target receptors controlling blood vessel function and other vital processes. They found that patients whose ME/CFS started after an infection had stronger connections between these antibodies and key symptoms like fatigue and muscle pain, suggesting these antibodies might play a role in how the disease develops.

Monitoring treatment harm in myalgic encephalomyelitis/chronic fatigue syndrome: A freedom-of-information study of National Health Service specialist centres in England.

McPhee, Graham, Baldwin, Adrian, Kindlon, Tom et al.·Journal of health psychology·2021

This study looked at how 38 ME/CFS specialist clinics in England monitor and report harms from treatments like graded exercise therapy and cognitive behavioural therapy. Researchers found that clinics were inconsistent in how they handle treatment-related harm, rarely warned patients about potential risks in their written materials, and reported zero cases of harm despite knowing many patients dropped out of treatment. The study suggests clinics need better systems to detect, record, and stop treatments when patients are being harmed.

E2 ModerateCohortPEM not requiredLongitudinal

Potential role of microbiome in Chronic Fatigue Syndrome/Myalgic Encephalomyelits (CFS/ME).

Lupo, Giuseppe Francesco Damiano, Rocchetti, Gabriele, Lucini, Luigi et al.·Scientific reports·2021

This study looked at the bacteria living in the gut and mouth of people with ME/CFS compared to healthy people. Researchers found that people with ME/CFS have different types and amounts of bacteria in their intestines, including fewer beneficial bacteria and more of certain harmful ones. They also found differences in the chemical makeup of patients' stool samples. These differences suggest that gut bacteria imbalance may play a role in ME/CFS, though scientists don't yet know if this is a cause or a result of the illness.

Inflammation-type dysbiosis of the oral microbiome associates with the duration of COVID-19 symptoms and long COVID.

Haran, John P, Bradley, Evan, Zeamer, Abigail L et al.·JCI insight·2021

This study looked at bacteria in the mouth of people with COVID-19 to understand why some people develop long COVID. Researchers found that people with long COVID had higher levels of inflammation-causing bacteria, particularly types called Prevotella and Veillonella. Interestingly, the oral bacteria patterns in long COVID patients resembled those seen in chronic fatigue syndrome patients, suggesting the microbiome may play a role in prolonged illness.

Immune System

E2 ModerateCohortPEM unclearObservational

Shadow Burden of Undiagnosed Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) on Society: Retrospective and Prospective-In Light of COVID-19.

Araja, Diana, Berkis, Uldis, Lunga, Asja et al.·Journal of clinical medicine·2021

This study examined how many people in Latvia may have ME/CFS symptoms but have never received a diagnosis, and investigated whether COVID-19 might cause similar long-term problems. Researchers compared symptom reports from diagnosed ME/CFS patients with undiagnosed people experiencing similar symptoms, and also tracked people who had recovered from COVID-19. The research found that undiagnosed patients face a significant financial burden on the healthcare system and themselves, and that COVID-19 can trigger ME/CFS-like symptoms in some people.

DiagnosticsLong COVID Overlap

E2 ModerateCohortPEM not requiredCross-Sectional

A retrospective cross-sectional study on tinnitus prevalence and disease associations in the Dutch population-based cohort Lifelines.

Schubert, Nick M A, Rosmalen, Judith G M, van Dijk, Pim et al.·Hearing research·2021

This study looked at how common tinnitus (ringing in the ears) is in a large group of Dutch adults and found that about one-third experience it at some point. The researchers discovered that tinnitus is linked to various conditions including hearing problems, heart issues, depression, and notably, chronic fatigue syndrome (ME/CFS). Understanding these connections may help doctors better treat tinnitus and related conditions.

Medical Care Situation of People with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome in Germany.

Froehlich, Laura, Hattesohl, Daniel B R, Jason, Leonard A et al.·Medicina (Kaunas, Lithuania)·2021

This study surveyed nearly 500 people with ME/CFS in Germany to understand how well they can access medical care and how satisfied they are with the care they receive. The researchers found that many patients struggle to get medical help because of cost and distance, and many are unhappy with their doctors' care. The study also created and tested a German language symptom questionnaire that could help doctors diagnose ME/CFS.

E2 ModerateCohortPEM not requiredCross-Sectional

Prevalence and risk factors of dry eye in 79,866 participants of the population-based Lifelines cohort study in the Netherlands.

Vehof, Jelle, Snieder, Harold, Jansonius, Nomdo et al.·The ocular surface·2021

This large study of nearly 80,000 Dutch adults found that about 9 out of 100 people experience dry eye symptoms. Interestingly, younger adults (ages 20-30) reported dry eye more often than expected. The researchers discovered that dry eye is connected to many different health conditions, including fibromyalgia, chronic fatigue syndrome, depression, and various autoimmune diseases.

Chronotropic Incompetence in Non-Hospitalized Patients with Post-COVID-19 Syndrome.

Jimeno-Almazán, Amaya, Pallarés, Jesús G, Buendía-Romero, Ángel et al.·Journal of clinical medicine·2021

Some people who recover from COVID-19 experience persistent fatigue and difficulty exercising for months afterward. This study tested 32 people with long-lasting COVID symptoms and found that about 12% had a specific heart problem called chronotropic incompetence—their heart rate doesn't increase normally during exercise. This heart rhythm problem may explain why some patients struggle with exercise intolerance after COVID-19.

Autonomic Nervous System

E2 ModerateCohortPEM not requiredCross-Sectional

Clinical Heterogeneity in ME/CFS. A Way to Understand Long-COVID19 Fatigue.

Murga, Iñigo, Aranburu, Larraitz, Gargiulo, Pascual A et al.·Frontiers in psychiatry·2021

This study examined 84 ME/CFS patients and 22 healthy controls using questionnaires to measure fatigue, pain, sleep quality, heart rate problems, thinking difficulties, mood, and other symptoms. Researchers used statistical clustering to group patients into five distinct subtypes based on their symptom patterns. The findings suggest that ME/CFS is not one-size-fits-all—some patients have high anxiety and depression without fibromyalgia, while others have fibromyalgia combined with heart rate regulation problems, hormone imbalances, or immune issues.

Immune SystemPost-Exertional Malaise

E2 ModerateCohortPEM unclearObservational

Male vs. Female Differences in Responding to Oxygen-Ozone Autohemotherapy (O2-O3-AHT) in Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS).

Chirumbolo, Salvatore, Valdenassi, Luigi, Franzini, Marianno et al.·Journal of clinical medicine·2021

This study looked at how well a treatment called oxygen-ozone autohemotherapy (O₂-O₃-AHT) worked for ME/CFS fatigue in men versus women. Two hundred patients received this treatment and filled out a fatigue questionnaire before and one month after. The results showed that women experienced more improvement in their fatigue than men did, especially among younger patients aged 14-29.

E2 ModerateCohortPEM unclearCase-Control

Health, Wellbeing, and Prognosis of Australian Adolescents with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS): A Case-Controlled Follow-Up Study.

Josev, Elisha K, Cole, Rebecca C, Scheinberg, Adam et al.·Journal of clinical medicine·2021

This study followed Australian teenagers with ME/CFS for about two years after diagnosis to see how they were doing. While many young people improved in mood and some symptoms, fatigue, pain, and overall quality of life stayed significantly worse compared to healthy teenagers. About two-thirds of the teens still had ME/CFS at follow-up, suggesting the condition often persists in the early years after diagnosis.

Pain and Sensitization

E2 ModeratePEM not requiredRegistry-Resource

Sex-Based Differences in Plasma Autoantibodies to Central Nervous System Proteins in Gulf War Veterans versus Healthy and Symptomatic Controls.

Abou-Donia, Mohamed B, Krengel, Maxine H, Lapadula, Elizabeth S et al.·Brain sciences·2021

Researchers found that Gulf War veterans with Gulf War illness have abnormal immune proteins in their blood that attack brain cells, and these patterns differ between men and women. The study also found that these same immune markers can help distinguish Gulf War illness from other similar conditions like ME/CFS and IBS. This discovery is important because it offers a possible objective blood test that doctors could use to identify and diagnose these difficult-to-recognize illnesses.

BiomarkersImmune System

Sarcoidosis among US Hispanics in a Nationwide Registry.

Innabi, Ayoub, Alzghoul, Bashar N, Kalra, Saminder et al.·Respiratory medicine·2021

This study looked at how sarcoidosis (a disease that causes inflammation in the body) affects Hispanic patients in the United States compared to non-Hispanic patients. Researchers surveyed nearly 3,835 people and found that Hispanic patients with sarcoidosis experience more depression, chronic pain, sleep problems, and job loss than non-Hispanic patients. The findings suggest that doctors may need to approach treatment differently for Hispanic patients with this condition.

Pain and SensitizationSleep

Characterizing long COVID in an international cohort: 7 months of symptoms and their impact.

Davis, Hannah E, Assaf, Gina S, McCorkell, Lisa et al.·EClinicalMedicine·2021

This study surveyed nearly 3,800 people from around the world who had long-lasting COVID-19 symptoms lasting more than 28 days. By seven months after illness onset, most participants had not fully recovered and experienced an average of 56 symptoms affecting multiple body systems. The three most persistent symptoms were fatigue, post-exertional malaise (feeling worse after activity), and cognitive problems, with nearly 86% experiencing relapses triggered by exercise, physical activity, mental stress, or other exertion.