Evidence browser

Prefrontal cortex oxygenation during incremental exercise in chronic fatigue syndrome.

Patrick Neary, J, Roberts, Andy D W, Leavins, Nina et al.·Clinical physiology and functional imaging·2008

This study measured oxygen levels in the brain during exercise in people with ME/CFS compared to healthy controls. People with ME/CFS became exhausted much faster, at lower exercise levels, and showed lower oxygen and blood volume in their brain during and after exercise, suggesting that reduced blood flow to the brain may be part of what causes exercise problems in ME/CFS.

Post-Exertional Malaise

The associations between basal salivary cortisol and illness symptomatology in chronic fatigue syndrome.

Torres-Harding, Susan, Sorenson, Matthew, Jason, Leonard et al.·Journal of applied biobehavioral research·2008

This study looked at cortisol, a stress hormone, in 108 people with ME/CFS to see if abnormal cortisol levels were connected to symptoms like fatigue and pain. The researchers found that people with unusual cortisol patterns—especially those who didn't show the normal daily rise and fall—reported higher levels of fatigue. While abnormal cortisol appears linked to some ME/CFS symptoms, scientists still aren't sure whether this hormonal change causes the illness or results from it.

Chronic fatigue syndrome in children aged 11 years old and younger.

Davies, S, Crawley, E·Archives of disease in childhood·2008

This study looked at young children under age 12 with ME/CFS at a specialist clinic in Bath, UK. The researchers found that even very young children (including one as young as 2 years old) can have ME/CFS and experience severe disability, with symptoms almost identical to those seen in teenagers. Children in this age group attended school only about 40% of the time on average and reported high levels of fatigue and pain.

E2 ModerateBehavioralPEM not requiredObservational

Lower frequency of IL-17F sequence variant (His161Arg) in chronic fatigue syndrome patients.

Metzger, Kristine, Frémont, Marc, Roelant, Chris et al.·Biochemical and biophysical research communications·2008

This study looked at a genetic variation in a protein called IL-17F that affects immune system inflammation. Researchers found that ME/CFS patients were less likely to carry a protective version of this genetic variant compared to healthy people. This suggests that the immune system's inflammatory response, particularly from a type of immune cell called Th17 cells, may play a role in ME/CFS.

Immune System

The neural correlates of fatigue: an exploratory imaginal fatigue provocation study in chronic fatigue syndrome.

Caseras, X, Mataix-Cols, D, Rimes, K A et al.·Psychological medicine·2008

This study used brain imaging to see how the brains of ME/CFS patients respond when they imagine feeling fatigued, compared to healthy people. Researchers found that patients with ME/CFS showed different patterns of brain activity during fatigue scenarios—some areas lit up more, while others lit up less—suggesting their brains may react more intensely to fatigue and have difficulty controlling these responses.

E2 ModerateCohortPEM not requiredObservational

Chronic fatigue syndrome after human parvovirus B19 infection without persistent viremia.

Seishima, Mariko, Mizutani, Yoko, Shibuya, Yoshinao et al.·Dermatology (Basel, Switzerland)·2008

This study looked at 210 patients who had parvovirus B19 infection to see how many developed ME/CFS afterward. Researchers found that the virus cleared from the bloodstream within 4-5 months in all patients tested, and having the virus stick around longer was not connected to developing CFS. However, patients who developed lasting symptoms did show persistently low immune protein (complement) levels, suggesting that ME/CFS after B19 may involve immune system changes rather than ongoing viral presence.

Immune System

E2 ModerateBehavioralPEM not requiredCross-Sectional

Exercise performance and chronic pain in chronic fatigue syndrome: the role of pain catastrophizing.

Nijs, Jo, Van de Putte, Karen, Louckx, Fred et al.·Pain medicine (Malden, Mass.)·2008

This study looked at 36 women with ME/CFS who experience widespread pain to understand how their thoughts about pain (called 'pain catastrophizing'—expecting the worst and feeling helpless) relate to their actual pain levels, ability to exercise, and daily functioning. Researchers found that negative thinking patterns about pain were strongly connected to how much bodily pain patients reported and how much their condition limited their activities. The study suggests that addressing these thought patterns might be an important part of managing ME/CFS with pain.

E2 ModerateBehavioralPEM unclearCross-Sectional

Symptoms, impairment and illness intrusiveness--their relationship with depression in women with CFS/ME.

Dancey, Christine P, Friend, Julie·Psychology & health·2008

This study looked at how ME/CFS symptoms and daily limitations affect depression in women with the illness. The researchers found that ME/CFS is particularly intrusive—it disrupts many areas of life more than other chronic illnesses do. How much the illness disrupts daily life turned out to be the strongest predictor of whether someone develops depression, more so than the symptoms or impairments alone.

E2 ModerateBehavioralPEM not requiredCross-Sectional

Attentional bias towards health-threat information in chronic fatigue syndrome.

Hou, Ruihua, Moss-Morris, Rona, Bradley, Brendan P et al.·Journal of psychosomatic research·2008

This study tested whether people with ME/CFS pay more attention to health-related threats compared to neutral information. Researchers used a simple computer task showing words and pictures related to health threats or neutral topics, and found that people with ME/CFS did indeed focus more on the health-threat information than healthy people did. This pattern of attention might help explain why some cognitive therapy approaches can be helpful for ME/CFS.

Cognitive Impairment

SleepAutonomic Nervous System

Higher heart rate and reduced heart rate variability persist during sleep in chronic fatigue syndrome: a population-based study.

Boneva, Roumiana S, Decker, Michael J, Maloney, Elizabeth M et al.·Autonomic neuroscience : basic & clinical·2007

This study found that people with ME/CFS have a faster heart rate and less heart rate variability (natural changes in heartbeat speed) during sleep compared to healthy people. These differences suggest that the nervous system in ME/CFS patients stays more activated even during sleep, which may be related to chemical imbalances in the body.

Reduced levels of oestrogen receptor beta mRNA in Swedish patients with chronic fatigue syndrome.

Gräns, Hanna, Nilsson, Maria, Dahlman-Wright, Karin et al.·Journal of clinical pathology·2007

This study looked at a protein called estrogen receptor beta in immune cells from ME/CFS patients and healthy people. Researchers found that ME/CFS patients had lower levels of this protein compared to healthy controls. Since estrogen plays a role in immune function and ME/CFS affects more women than men, this finding suggests hormone-related immune problems might be involved in the disease.

Immune System

E2 ModerateCohortPEM not requiredLongitudinal

Sleep quality perception in the chronic fatigue syndrome: correlations with sleep efficiency, affective symptoms and intensity of fatigue.

Neu, Daniel, Mairesse, Olivier, Hoffmann, Guy et al.·Neuropsychobiology·2007

ME/CFS patients often report feeling like they have poor sleep quality, even though doctors cannot always find obvious problems when measuring sleep objectively. This study compared how ME/CFS patients and healthy people rated their own sleep quality and found that ME/CFS patients consistently reported worse sleep, despite having similar sleep efficiency measurements. The poor sleep quality perception was somewhat linked to fatigue severity but not related to depression or anxiety symptoms.

Sleep

Cortisol and severe fatigue: a longitudinal study in adolescent girls.

Ter Wolbeek, Maike, van Doornen, Lorenz J P, Coffeng, Luc E et al.·Psychoneuroendocrinology·2007

This study looked at whether girls with severe, ongoing fatigue have different stress hormone (cortisol) levels than girls without fatigue. Researchers tested cortisol levels at different times over a year and found that while fatigued girls reported much worse symptoms overall, their cortisol levels were actually normal and similar to non-fatigued girls. This suggests that severe fatigue in adolescents may not be caused by problems with how the body manages stress hormones.

Endocrine Disruption

E2 ModerateBehavioralPEM not requiredCross-Sectional

Usefulness of an abnormal cardiovascular response during low-grade head-up tilt-test for discriminating adolescents with chronic fatigue from healthy controls.

Wyller, Vegard Bruun, Due, Reidar, Saul, J Philip et al.·The American journal of cardiology·2007

This study tested how the hearts of adolescents with ME/CFS respond to mild physical stress (tilting the body slightly upright for 15 minutes) compared to healthy teenagers. Researchers found that young people with ME/CFS had abnormal heart and blood vessel responses during this test—their hearts beat faster, their blood pressure increased more, and their stroke volume (amount of blood pumped per heartbeat) decreased more than in healthy controls. These differences suggest that ME/CFS involves problems with how the body regulates blood flow and heart function during even mild stress.

Autonomic Nervous System

Psychological, medical, and pharmacological correlates of persistent genital arousal disorder.

Leiblum, Sandra, Seehuus, Martin, Goldmeier, David et al.·The journal of sexual medicine·2007

This study surveyed 156 women about persistent genital arousal disorder (PGAD), a condition involving unwanted arousal sensations. Women with full PGAD were more likely to experience depression, anxiety, panic attacks, and chronic fatigue compared to women with milder symptoms or no condition. The researchers suggest that anxiety and worry about these sensations may play a role in making PGAD worse.

E2 ModerateCohortPEM not requiredObservational

The relative impact of 13 chronic conditions across three different outcomes.

Perruccio, Anthony V, Power, J Denise, Badley, Elizabeth M·Journal of epidemiology and community health·2007

This study looked at how 13 common long-term health conditions—including ME/CFS and fibromyalgia—affect people's daily activities, overall health, and doctor visits. Researchers used information from over 130,000 Canadians and found that ME/CFS and fibromyalgia had the strongest individual impact on activity limitations and poor health ratings, while conditions like arthritis and heart disease affected the most people overall in the population.

Actuarial analysis of private payer administrative claims data for women with endometriosis.

Mirkin, David, Murphy-Barron, Carrieann, Iwasaki, Kosuke·Journal of managed care pharmacy : JMCP·2007

This study looked at insurance claims from nearly 4 million people to understand how common endometriosis is and how much it costs to treat. Researchers found that women with endometriosis spend significantly more on medical care than other women, have frequent hospital stays and surgeries, and often have other health conditions at the same time—including chronic fatigue syndrome. The study shows endometriosis is a serious, expensive condition that affects many aspects of a woman's health.

E2 ModerateCohortPEM unclearCross-Sectional

The experience of cancer-related fatigue and chronic fatigue syndrome: a qualitative and comparative study.

Bennett, Barbara, Goldstein, David, Friedlander, Michael et al.·Journal of pain and symptom management·2007

This study compared how fatigue affects women with cancer-related fatigue (after breast cancer treatment) versus women with ME/CFS. Both groups described very similar experiences: exhaustion, problems with thinking and memory, and mood changes. Women with ME/CFS also reported muscle pain and flu-like symptoms more often. The researchers found that these two conditions share a common set of disabling symptoms, suggesting they may involve similar underlying causes despite different triggers.

Cognitive Impairment

Prevalence of chronic fatigue syndrome in metropolitan, urban, and rural Georgia.

Reeves, William C, Jones, James F, Maloney, Elizabeth et al.·Population health metrics·2007

This study surveyed over 5,600 people in Georgia to find out how many have ME/CFS. Researchers found that about 2.5% of adults aged 18-59 have the condition, which is higher than estimates from other parts of the United States. Interestingly, the disease affected men and women very differently depending on whether they lived in cities or rural areas.

Assessment of vulvodynia symptoms in a sample of US women: a prevalence survey with a nested case control study.

Arnold, Lauren D, Bachmann, Gloria A, Rosen, Raymond et al.·American journal of obstetrics and gynecology·2007

This study looked at how common vulvodynia (chronic pain in the vulva) is among American women and found that about 4% currently experience it. Women with vulvodynia were more likely to also have other conditions like chronic fatigue syndrome, fibromyalgia, depression, and irritable bowel syndrome. Many women reported that the pain significantly affected their sexual life and daily activities.