Evidence browser

E0 ConsensusGuidelinePEM unclearGuideline

Cognitive and mood-state changes in patients with chronic fatigue syndrome.

Grafman, J, Johnson, R, Scheffers, M·Reviews of infectious diseases·1991

This review examined whether ME/CFS causes problems with memory, thinking, and mood. The researchers found that while some people with acute mono or EBV infection may have thinking difficulties, they couldn't confirm this happens in ME/CFS patients using objective tests. However, they did notice that people with ME/CFS often have depression or anxiety either before or alongside their illness.

Cognitive Impairment

A report--chronic fatigue syndrome: guidelines for research.

Sharpe, M C, Archard, L C, Banatvala, J E et al.·Journal of the Royal Society of Medicine·1991

This 1991 document provides guidelines for how researchers should study ME/CFS to ensure consistent and reliable findings. Rather than reporting new experimental results, it offers recommendations on how to standardize research methods, study design, and patient definitions. It represents the thinking of leading medical experts who were trying to establish a common framework for ME/CFS research.

Diagnostics

E0 ConsensusReviewPEM unclearReview-Narrative

Post-infectious neuromyasthenia (chronic fatigue syndrome): a summary of ongoing studies.

Salit, I E, Abbey, S E, Moldofsky, H et al.·Canada diseases weekly report = Rapport hebdomadaire des maladies au Canada·1991

This 1991 review examined multiple ongoing studies about ME/CFS (then called post-infectious neuromyasthenia), a condition that causes extreme fatigue and other symptoms following infections. The researchers summarized what different studies were finding about how this illness affects the body and brain. This work helped organize early research efforts to better understand this serious condition.

Post-Exertional Malaise

Review of laboratory findings for patients with chronic fatigue syndrome.

Buchwald, D, Komaroff, A L·Reviews of infectious diseases·1991

This review examined blood test results from many ME/CFS patients and found several patterns in how their immune systems function differently. The most common findings included weaker natural killer cells (which normally help fight infections), unusual antibody levels, and signs of past Epstein-Barr virus infection. These patterns appeared across multiple studies, suggesting they may be important features of the condition.

Immune System

An overview of chronic fatigue syndrome.

Krupp, L B, Mendelson, W B, Friedman, R·The Journal of clinical psychiatry·1991

This review examined research on ME/CFS to understand whether the illness is caused by psychological factors, immune system problems, or both. Researchers found that ME/CFS patients experience more disabling fatigue than people with other chronic illnesses, and some have immune system abnormalities. However, many ME/CFS patients have no psychiatric illness, suggesting ME/CFS is a real medical condition separate from depression.

Immune System

Chronic fatigue syndrome and depression: cause, effect, or covariate.

Abbey, S E, Garfinkel, P E·Reviews of infectious diseases·1991

Many people with ME/CFS experience depression, but it's unclear why. This review examines four possible explanations: depression might be the main illness with fatigue as a symptom, depression might develop because of having ME/CFS, both conditions might occur together separately, or depression might be incorrectly diagnosed. The authors discuss how depression can affect medical tests used to study ME/CFS, which is important to understand when interpreting research results.

Cognitive Impairment

E0 ConsensusReviewPEM unclearEditorial

Serologic and immunologic responses in chronic fatigue syndrome with emphasis on the Epstein-Barr virus.

Jones, J F·Reviews of infectious diseases·1991

This review examined whether ME/CFS is connected to Epstein-Barr virus (EBV), the virus that causes mono. Researchers found that people with ME/CFS had higher levels of antibodies to EBV compared to healthy people, but this doesn't prove the virus causes the disease. They also found that immune cells called natural killer cells—which help fight infections—work differently in ME/CFS patients, though the findings varied between studies.

Immune System

Postviral fatigue syndrome: time for a new approach.

David, A S, Wessely, S, Pelosi, A J·British medical journal (Clinical research ed.)·1988

This 1988 review examined how ME/CFS was being studied and discussed in medical literature, finding significant problems with how research was being conducted. The authors argued that the condition should not be viewed as simply 'all in your head' or 'purely physical,' but rather as involving multiple factors affecting the body and mind. They called for better research methods and clearer definitions before doctors could effectively help patients.

Diagnostics

Testing the Feasibility of a Self-Help Intervention That Includes Lymphatic Drainage to Reduce Fatigue-Related Symptoms Among Patients with Long COVID in General Practice: Experiences from Our Randomized Controlled Trial (RCT).

Riste, Lisa, Perrin, Raymond, Mulholland, Thomas et al.·Infectious diseases and therapy·2026

Researchers tested whether a simple self-help program including gentle massage, stretching, breathing exercises, and temperature therapy could help reduce fatigue in people with long COVID. About 91% of people who were invited agreed to participate in the study. Those who used the self-help program showed slightly more improvement in their fatigue over three months compared to those who didn't receive the program, suggesting this low-cost approach may help some people feel better.

Tuina therapy for patients with chronic fatigue syndrome: a randomized controlled trial.

Wang, Shoujian, Ren, Jun, Zhou, Xin et al.·Journal of translational medicine·2026

This study tested whether Tuina, a hands-on therapy from traditional Chinese medicine, could help people with ME/CFS feel less tired. Over 4 weeks, people who received Tuina three times per week alongside their usual care felt significantly better than those who received usual care alone. The improvement was especially noticeable for physical tiredness, and people also reported better sleep and less anxiety.

Sleep

Interpretation bias modification (CBM-I) for fatigue in long term health conditions - A feasibility study.

Hughes, Alicia, Tyson, Gabriella, Moss-Morris, Rona et al.·Behaviour research and therapy·2026

This study tested a new online training program designed to help people with long-term illnesses (including ME/CFS and long COVID) reduce fatigue by changing how they interpret ambiguous situations. People in the study completed 12 online training sessions and were tracked for four months. The training was popular with participants, most people completed it, and it showed promise in reducing fatigue and low mood.

Vitamin D in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome After COVID-19 or Vaccination: A Randomized Controlled Trial.

Kodama, Shinichiro, Nakata, Mitsuko, Konishi, Nafuko et al.·Nutrients·2026

This study tested whether vitamin D supplementation could help people with ME/CFS who developed the condition after COVID-19 vaccination or infection and had low vitamin D levels. Half the participants received vitamin D supplements plus guidance on diet and sun exposure, while the other half received only the supplement. The group that received full guidance had significantly more symptom improvement, with 16 people improving enough to no longer meet ME/CFS diagnostic criteria compared to just 1 person in the other group.

Effect of Prolong Life With Nine Turn Method on chronic fatigue syndrome clinical symptoms and roles of gut microbiota: A exploratory randomized controlled trial.

Cui, Jiahe, Xie, Fangfang, Gu, Yuanjia et al.·Complementary therapies in medicine·2026

This study tested whether a traditional Chinese exercise method called Prolong Life With Nine Turn Method (PLWNT) could help people with ME/CFS feel less tired and have fewer stomach problems. Over 8 weeks, 96 patients either did this exercise program or received cognitive behavioral therapy. The exercise group showed meaningful improvements in fatigue and digestive symptoms, with changes in their gut bacteria that may have contributed to these improvements.

The breath and mind connection in young people with post-COVID syndrome: feasibility and acceptability of a pilot randomised co-designed intervention.

Wells, Charlotte, Christie, Deborah, Johnston, Rebecca et al.·European journal of pediatrics·2026

This study tested whether a treatment combining breathing retraining and talk therapy could help young people (ages 12–18) recover from long COVID symptoms. Thirty-two young people received either standard care alone or standard care plus the new intervention over 6 months. Most participants found the intervention helpful and it was practical to run in an NHS clinic, but both groups improved similarly over time, suggesting that natural recovery, rather than the intervention itself, may have driven the improvements.

E1 ReplicatedTrialPEM requiredRCT

Efficacy and Safety of Enzyme-Derived Deer Velvet Extract Supplementation on Adults with Chronic Fatigue: a Randomized, Placebo-Controlled, Double-Blind Trial.

Jamrasi, Parivash, Seo, Ji-Won, Sung, Yunho et al.·Journal of microbiology and biotechnology·2026

A new study tested whether a supplement made from deer velvet extract (called YC-1101) could reduce fatigue in 100 adults with chronic fatigue syndrome. Over 8 weeks, people taking the supplement reported improvements in tiredness and ease of fatigue compared to those taking placebo, and they also showed better exercise capacity. However, the study is very recent (2026) and peer-review status is unclear, so these findings need confirmation in other research before drawing firm conclusions.

BiomarkersInterventions

A digital platform with activity tracking for energy management support in long COVID: a randomised controlled trial.

Sanal-Hayes, Nilihan Em, Hayes, Lawrence D, Mair, Jacqueline L et al.·Nature communications·2026

Researchers tested whether a smartphone app called 'Pace Me' combined with an activity tracker could help people with long COVID manage their energy better and reduce post-exertional malaise (the worsening of symptoms after activity). Over 6 months, some participants used the app with the tracker and received helpful messages when they approached their daily activity limit, while others used a basic version of the app. Both groups improved slightly, but there was no meaningful difference between them.

Post-Exertional Malaise

E1 ReplicatedTrialPEM unclearObservational

Effects of acupuncture and moxibustion on heart rate variability in chronic fatigue syndrome patients: Regulating the autonomic nervous system in a clinical randomized controlled trial.

Li, Tong, Litscher, Gerhard, Zhou, Yudian et al.·Complementary therapies in medicine·2025

This study tested whether acupuncture and moxibustion (a traditional heat therapy) could help people with chronic fatigue syndrome by measuring changes in heart rate variability, which reflects how well the nervous system is working. Researchers divided 175 CFS patients into groups receiving different acupuncture treatments, fake acupuncture, or moxibustion over 10 sessions. Both acupuncture and moxibustion reduced fatigue symptoms, with combining both approaches working best, and the treatments appeared to help balance the body's stress response system.

Autonomic Nervous System

Integrative multimodal treatment approach for patients suffering from Post-COVID syndrome: a study based on qualitative interviews with individuals participating in an 11-week day clinic program.

Uecker, Christine, Schlee, Christoph, Utz, Sandra et al.·Frontiers in public health·2025

This study looked at whether a combined treatment program could help people with Post-COVID syndrome (including severe cases similar to ME/CFS). Twenty patients participated in an 11-week day clinic program that used multiple approaches like physical therapy, nutrition, stress management, and mental health support. Patients reported feeling significantly better after the program, with improvements in fatigue, pain, and their ability to cope with daily activities.

The Use of Heart Rate Variability-Biofeedback (HRV-BF) as an Adjunctive Intervention in Chronic Fatigue Syndrome (CSF/ME) in Long COVID: Results of a Phase II Controlled Feasibility Trial.

Cossu, Giulia, Kalcev, Goce, Primavera, Diego et al.·Journal of clinical medicine·2025

This study tested whether a technique called heart rate variability biofeedback (HRV-BF)—which uses breathing exercises and computer feedback to help regulate your nervous system—could help people with Long COVID who have severe fatigue. Participants received 10 sessions over 5 weeks, and the results showed that people in the treatment group experienced greater improvement in severe fatigue compared to those receiving usual care. The treatment was well-tolerated with very few people dropping out, suggesting it could be a helpful add-on therapy for ME/CFS.

Autonomic Nervous System