Evidence browser

E2 ModerateMechanismPEM not requiredMechanistic

Visible and near-infrared spectral changes in the thumb of patients with chronic fatigue syndrome.

Sakudo, Akikazu, Kato, Yukiko Hakariya, Tajima, Seiki et al.·Clinica chimica acta; international journal of clinical chemistry·2009

Researchers used a special light-based scanning tool to examine the thumbs of ME/CFS patients and healthy people, looking for differences in blood and oxygen levels. They found that ME/CFS patients had higher oxygen-carrying proteins in their blood, less water in their tissues, and signs of faster energy use in their cells. These findings suggest that ME/CFS patients' bodies may be working harder than usual, even at rest.

Energy Metabolism

RETRACTED: Detection of an infectious retrovirus, XMRV, in blood cells of patients with chronic fatigue syndrome.

Lombardi, Vincent C, Ruscetti, Francis W, Das Gupta, Jaydip et al.·Science (New York, N.Y.)·2009

This study, which has since been retracted, reported finding a virus called XMRV in blood cells from most ME/CFS patients tested, but rarely in healthy people. The researchers showed that this virus could be grown in the lab and transmitted between cells. However, subsequent studies by other scientists could not reproduce these findings, leading to the retraction of this paper.

E2 ModerateCohortPEM unclearCross-Sectional

Vitamin D metabolites as clinical markers in autoimmune and chronic disease.

Blaney, Greg P, Albert, Paul J, Proal, Amy D·Annals of the New York Academy of Sciences·2009

This study measured two types of vitamin D in the blood of patients with autoimmune and chronic diseases, including ME/CFS. The researchers found that a specific form of vitamin D (1,25-D) at high levels was associated with these conditions, but the commonly-tested form of vitamin D (25-D) was not. This suggests doctors may need to test for the right type of vitamin D to properly assess autoimmune disease.

BiomarkersImmune System

Gut MicrobiomeEnergy Metabolism

Increased d-lactic Acid intestinal bacteria in patients with chronic fatigue syndrome.

Sheedy, John R, Wettenhall, Richard E H, Scanlon, Denis et al.·In vivo (Athens, Greece)·2009

This study found that people with ME/CFS have higher levels of specific bacteria in their gut that produce a substance called D-lactic acid. These bacteria were found in much larger quantities in stool samples from ME/CFS patients compared to healthy people. The researchers suggest this excess D-lactic acid might help explain why some ME/CFS patients experience brain fog and cognitive problems.

E2 ModerateCohortPEM not requiredObservational

Effect of supplement with lactic-acid producing bacteria on fatigue and physical activity in patients with chronic fatigue syndrome.

Sullivan, Asa, Nord, Carl E, Evengård, Birgitta·Nutrition journal·2009

This small study tested whether specific probiotic bacteria (live microorganisms that may benefit gut health) could reduce fatigue and improve physical activity in ME/CFS patients. Fifteen patients took probiotics for 4 weeks and were monitored for changes in fatigue, physical activity, and cognitive function. While some patients reported feeling better overall, the study did not find significant improvements in fatigue or activity levels, though cognitive function did improve.

Gut MicrobiomeImmune System

E2 ModerateCohortPEM unclearCase-Control

Vaccination as teenagers against meningococcal disease and the risk of the chronic fatigue syndrome.

Magnus, Per, Brubakk, Oddbjørn, Nyland, Harald et al.·Vaccine·2009

This study investigated whether a meningococcal vaccine given to teenagers in Norway in 1988-1989 was linked to the later development of ME/CFS. Researchers compared 201 people diagnosed with ME/CFS to 389 people without the condition and found no meaningful difference in vaccination rates between the two groups. The findings suggest that receiving this particular vaccine as a teenager does not increase the risk of developing ME/CFS.

The lifestyle of patients with chronic fatigue syndrome and the effect on fatigue and functional impairments.

Goedendorp, M M, Knoop, H, Schippers, G M et al.·Journal of human nutrition and dietetics : the official journal of the British Dietetic Association·2009

This study looked at the daily habits (diet, smoking, weight, exercise) of 247 people with ME/CFS and whether these habits affected their fatigue or ability to do activities. Researchers found that ME/CFS patients actually had healthier lifestyles than the general population, eating less fatty food and smoking less. Surprisingly, the study found no connection between lifestyle choices and how severe someone's fatigue or disability was.

An assessment of prospective memory retrieval in women with chronic fatigue syndrome using a virtual-reality environment: an initial study.

Attree, Elizabeth A, Dancey, Christine P, Pope, Alison L·Cyberpsychology & behavior : the impact of the Internet, multimedia and virtual reality on behavior and society·2009

This study examined memory problems in women with ME/CFS using a computer-based virtual environment. Researchers tested two types of memory: remembering things after they happen (like recalling a list of words) and remembering to do something in the future (like remembering to take medication). Women with ME/CFS showed noticeable difficulties with both types of memory, particularly with recalling information, though some future-memory tasks showed only subtle differences.

Cognitive Impairment

Molecular study of receptor for advanced glycation endproduct gene promoter and identification of specific HLA haplotypes possibly involved in chronic fatigue syndrome.

Carlo-Stella, N, Bozzini, S, De Silvestri, A et al.·International journal of immunopathology and pharmacology·2009

This study looked at two genes related to inflammation in 75 Italian ME/CFS patients and compared them to 141 healthy controls. The researchers found that certain genetic variations in the RAGE gene and immune system genes called HLA were more common in ME/CFS patients, suggesting these genetic differences might increase risk for the condition. The findings suggest ME/CFS may involve inherited factors that affect how the immune system responds.

Energy MetabolismPost-Exertional Malaise

Physiological cost of walking in those with chronic fatigue syndrome (CFS): a case-control study.

Paul, Lorna, Rafferty, Danny, Marshal, Rebecca·Disability and rehabilitation·2009

This study compared how much energy people with ME/CFS use when walking compared to healthy people. Researchers found that people with ME/CFS walk more slowly and use more energy per unit of distance covered, meaning their bodies have to work harder to move the same distance as healthy people.

Are chronic fatigue and chronic fatigue syndrome valid clinical entities across countries and health-care settings?

Hickie, Ian, Davenport, Tracey, Vernon, Suzanne D et al.·The Australian and New Zealand journal of psychiatry·2009

This large international study analyzed data from nearly 38,000 people across 21 countries to determine whether chronic fatigue and ME/CFS are real, recognizable conditions. Researchers found that people with these conditions share a consistent pattern of five main symptom types—muscle pain and fatigue, thinking difficulties, inflammation-related symptoms, sleep problems, and mood changes—regardless of where they live or which type of doctor they see. This consistency across different countries and healthcare settings provides strong evidence that chronic fatigue and ME/CFS are genuine medical conditions, not just psychiatric problems.

Diagnostics

Autoantibodies, polymorphisms in the serotonin pathway, and human leukocyte antigen class II alleles in chronic fatigue syndrome: are they associated with age at onset and specific symptoms?

Ortega-Hernandez, Oscar-Danilo, Cuccia, Mariaclara, Bozzini, Sara et al.·Annals of the New York Academy of Sciences·2009

This study looked at whether certain genetic traits and immune markers in the blood are linked to when ME/CFS develops and what symptoms people experience. Researchers tested 81 ME/CFS patients for specific genes related to serotonin (a brain chemical), immune system genes, and antibodies. They found that different genetic patterns were associated with developing ME/CFS at different ages and with certain symptoms like joint pain and fever, but not muscle pain.

E2 ModerateBehavioralPEM not requiredCross-Sectional

Associations between pet ownership and self-reported health status in people suffering from chronic fatigue syndrome.

Wells, Deborah L·Journal of alternative and complementary medicine (New York, N.Y.)·2009

Researchers asked 193 people with ME/CFS whether they owned pets and how their health was doing. About 58% owned pets, mostly dogs and cats. While pet owners reported feeling that their animals helped their mental well-being, the study found no clear statistical link between owning a pet and having better health scores overall.

E2 ModerateCohortPEM not requiredLongitudinal

Chronic fatigue syndrome after infectious mononucleosis in adolescents.

Katz, Ben Z, Shiraishi, Yukiko, Mears, Cynthia J et al.·Pediatrics·2009

This study followed 301 teenagers with infectious mononucleosis (mono) to see how many developed ME/CFS afterward. Researchers checked in at 6, 12, and 24 months and found that fewer teenagers had ME/CFS as time went on: 13% at 6 months, 7% at 12 months, and 4% at 24 months. All 13 teenagers still diagnosed with ME/CFS at 24 months were female, and they had reported more severe fatigue earlier in their illness.

Anticardiolipin antibodies in the sera of patients with diagnosed chronic fatigue syndrome.

Hokama, Yoshitsugi, Campora, Cara Empey, Hara, Cynthia et al.·Journal of clinical laboratory analysis·2009

Researchers tested blood samples from ME/CFS patients and found abnormal antibodies called anticardiolipin antibodies (ACAs) in 95% of the samples. These antibodies mistakenly attack cardiolipin, a substance found in cell membranes. The study suggests that something in the immune system may be going wrong in ME/CFS, possibly affecting how cells produce energy.

E2 ModerateBehavioralPEM not requiredCross-Sectional

Chronic fatigue syndrome combines increased exercise-induced oxidative stress and reduced cytokine and Hsp responses.

Jammes, Y, Steinberg, J G, Delliaux, S et al.·Journal of internal medicine·2009

This study found that people with ME/CFS experience unusual stress on their cells during exercise, particularly involving harmful molecules called free radicals. Their bodies also fail to mount normal protective responses—both in terms of producing protective proteins (heat shock proteins) and inflammatory markers that healthy people produce during exertion. This combination of excessive cellular damage and insufficient protective response may explain why exercise is so difficult for people with ME/CFS.

Post-Exertional Malaise

Use of the Temperament and Character Inventory (TCI) for assessment of personality in chronic fatigue syndrome.

Van Campen, Elise, Van Den Eede, Filip, Moorkens, Greta et al.·Psychosomatics·2009

This study looked at whether people with ME/CFS have certain personality traits that might be connected to their illness. Researchers gave a personality questionnaire to 38 people with ME/CFS and 42 healthy people, and found that those with ME/CFS scored higher on two traits: being cautious about potential harm and being persistent in their efforts. The findings suggest that these personality characteristics might play a role in how ME/CFS develops or continues.