Evidence browser

DiagnosticsCognitive Impairment

What is in a name? Comparing diagnostic criteria for chronic fatigue syndrome with or without fibromyalgia.

Meeus, Mira, Ickmans, Kelly, Struyf, Filip et al.·Clinical rheumatology·2016

This study compared people with ME/CFS to people with multiple sclerosis and healthy volunteers to see how sick they were and how well they could function. Researchers found that people with ME/CFS had worse physical abilities (like muscle strength and recovery), more severe symptoms, lower quality of life, and more difficulty with daily activities. They also discovered that when ME/CFS patients also had fibromyalgia (widespread pain), their overall symptom burden was much greater.

E2 ModerateCohortPEM not requiredLongitudinal

Workers on transformation of the shelter object of the Chernobyl nuclear power plant into an ecologically-safe system show qEEG abnormalities and cognitive dysfunctions: A follow-up study.

Loganovsky, Konstantyn, Perchuk, Iryna, Marazziti, Donatella·The world journal of biological psychiatry : the official journal of the World Federation of Societies of Biological Psychiatry·2016

This study followed 196 workers who helped clean up and secure the damaged Chernobyl nuclear reactor between 2004 and 2008. Researchers tested their brain electrical activity and thinking skills before and after the work. The workers showed changes in brain wave patterns and developed mild memory and concentration problems after exposure to radiation, similar to symptoms seen in chronic fatigue syndrome.

Abnormal resting state functional connectivity in patients with chronic fatigue syndrome: an arterial spin-labeling fMRI study.

Boissoneault, Jeff, Letzen, Janelle, Lai, Song et al.·Magnetic resonance imaging·2016

This study used a special brain imaging technique to look at how different parts of the brain communicate with each other in ME/CFS patients compared to healthy people. Researchers found that people with ME/CFS have unusual patterns of brain communication, particularly in areas related to memory, thinking, and movement. Importantly, the strength of connections in memory-related brain regions was linked to how severe patients' fatigue symptoms were.

E2 ModerateCohortPEM unclearLongitudinal

Neurocognitive complaints and functional status among patients with chronic fatigue syndrome and fibromyalgia.

Schmaling, Karen B, Betterton, Karran L·Quality of life research : an international journal of quality of life aspects of treatment, care and rehabilitation·2016

This study followed 93 patients with ME/CFS over 18 months to understand how cognitive problems (like memory and perception difficulties) and physical function change over time. Patients who had both ME/CFS and fibromyalgia reported more pain, worse physical function, and more cognitive difficulties than those with ME/CFS alone. Interestingly, pain improved over time only for the ME/CFS-only group, suggesting that having both conditions may make recovery slower and more complicated.

Low putamen activity associated with poor reward sensitivity in childhood chronic fatigue syndrome.

Mizuno, Kei, Kawatani, Junko, Tajima, Kanako et al.·NeuroImage. Clinical·2016

This study looked at how the brains of children with ME/CFS respond to rewards compared to healthy children. Using brain imaging, researchers found that a brain region called the putamen (involved in motivation) showed less activity in children with ME/CFS, especially when facing smaller rewards. Lower activity in this area was linked to worse fatigue and less enjoyment from learning.

The impact of chronic fatigue syndrome on cognitive functioning in adolescents.

Nijhof, Linde N, Nijhof, Sanne L, Bleijenberg, Gijs et al.·European journal of pediatrics·2016

This study looked at how ME/CFS affects thinking and concentration in teenagers. Researchers compared 59 teenagers with ME/CFS to 40 healthy teenagers and found that those with ME/CFS had lower scores on intelligence tests than their school grades would predict. When comparing teenagers' current test scores to their performance before they got sick, the ME/CFS group showed a significant decline, while healthy teens did not.

Pain and SensitizationCognitive Impairment

Associations Between Cognitive Performance and Pain in Chronic Fatigue Syndrome: Comorbidity with Fibromyalgia Does Matter.

Ickmans, Kelly, Meeus, Mira, De Kooning, Margot et al.·Pain physician·2015

This study looked at whether pain and thinking problems are connected in people with ME/CFS, and whether having fibromyalgia alongside ME/CFS changes this relationship. Researchers tested 48 patients with ME/CFS (some with fibromyalgia, some without) and 30 healthy people on memory and attention tasks, then measured their pain responses. They found that the type of pain problem matters: in patients with both conditions, a specific pain-processing difference predicted thinking problems, while in ME/CFS-only patients, reported pain levels predicted thinking problems.

E2 ModerateCohortPEM unclearObservational

Computerized training improves verbal working memory in patients with myalgic encephalomyelitis/chronic fatigue syndrome: A pilot study.

Maroti, Daniel, Westerberg, Annika Fryxell, Saury, Jean-Michel et al.·Journal of rehabilitation medicine·2015

Many people with ME/CFS struggle with memory and thinking problems. This small study tested whether spending 30-45 minutes a day for 5 weeks doing computerized memory exercises on a computer could help. Nine out of eleven patients who completed the training showed real improvements in working memory and attention, while a control group of patients who didn't do the training showed no improvement.

Attention network test: assessment of cognitive function in chronic fatigue syndrome.

Togo, Fumiharu, Lange, Gudrun, Natelson, Benjamin H et al.·Journal of neuropsychology·2015

This study tested whether a computer-based attention test called the Attention Network Task (ANT) could measure thinking and processing speed problems in ME/CFS patients. Researchers compared 41 ME/CFS patients (some with depression, some without) to 29 healthy controls and found that ME/CFS patients took longer to respond to tasks, especially when the tasks were complex, even though they made the same number of mistakes as controls. This suggests that slowed thinking speed, rather than errors, may be the main cognitive problem in ME/CFS.

Cognitive dysfunction in adolescents with chronic fatigue: a cross-sectional study.

Sulheim, Dag, Fagermoen, Even, Sivertsen, Øyvind Stople et al.·Archives of disease in childhood·2015

This study compared thinking and memory skills in teenagers with chronic fatigue to healthy teenagers. Teenagers with chronic fatigue performed worse on tests of processing speed (how fast they could think), working memory (holding information in mind), and learning new information. These differences were not explained by depression, anxiety, or sleep problems alone.

Pain and SensitizationSleepCognitive Impairment

A Cross Cultural Comparison of Disability and Symptomatology Associated with CFS.

Zdunek, Maria, Jason, Leonard A, Evans, Meredyth et al.·International journal of psychology and behavioral sciences·2015

This study compared ME/CFS symptoms and disability between patients in the United States and the United Kingdom to see if the illness looks different depending on where people live. Researchers found that UK patients reported more mental health problems, pain, memory/concentration issues, and immune symptoms, while US patients more often experienced sudden illness onset and attributed their illness to physical causes. The study suggests that ME/CFS may present somewhat differently across these two countries.

E2 ModerateCohortPEM requiredCross-Sectional

Study findings challenge the content validity of the Canadian Consensus Criteria for adolescent chronic fatigue syndrome.

Asprusten, Tarjei Tørre, Fagermoen, Even, Sulheim, Dag et al.·Acta paediatrica (Oslo, Norway : 1992)·2015

Researchers tested whether the Canadian Consensus Criteria—a set of guidelines used to diagnose ME/CFS in teenagers—actually identify meaningful differences between patients. They compared 120 adolescents with ME/CFS, grouping them by whether they met these criteria or not. The study found that the two groups were nearly identical in most disease markers and how they recovered over time, suggesting the criteria may not be capturing important real-world differences between patients.

The effect of fatigue and fibromyalgia on sexual dysfunction in women with chronic fatigue syndrome.

Blazquez, Alicia, Ruiz, Eva, Aliste, Luisa et al.·Journal of sex & marital therapy·2015

This study examined sexual problems in 615 women with ME/CFS and found that sexual dysfunction was more common in those with worse fatigue, more cognitive and nervous system symptoms, and co-occurring conditions like fibromyalgia or Sjögren's syndrome. The researchers used a validated questionnaire to measure sexual satisfaction and identified patterns linking symptom severity to sexual health problems. This suggests that ME/CFS symptoms directly impact intimate relationships and sexual function.

Endogenous event-related potentials in patients with primary Sjögren's syndrome without central nervous system involvement.

Dziadkowiak, E, Sebastian, A, Wiland, P et al.·Scandinavian journal of rheumatology·2015

This study looked at brain electrical activity in patients with Sjögren's syndrome (an autoimmune disease affecting moisture-producing glands) to see if they had subtle thinking or processing problems. Researchers found that patients showed slightly delayed brain responses to cognitive tasks, and these delays were linked to how long they'd had the disease and how inflamed their salivary glands were. Patients with both Sjögren's syndrome and chronic fatigue syndrome showed different patterns than those with Sjögren's syndrome alone.

E2 ModerateCohortPEM requiredCross-Sectional

Chronic Fatigue Syndrome versus Systemic Exertion Intolerance Disease.

Jason, Leonard A, Sunnquist, Madison, Brown, Abigail et al.·Fatigue : biomedicine, health & behavior·2015

Researchers compared different ways of diagnosing ME/CFS by testing 796 patients using a new diagnostic system called SEID (Systemic Exertion Intolerance Disease). They found that the new SEID criteria identified about 88% of patients, which is similar to an older diagnostic system but captures a larger group than some other definitions. The study suggests that different diagnostic criteria can identify different sizes and severity levels of patient populations.

Cognitive ImpairmentPost-Exertional Malaise

SleepCognitive Impairment

The association between daytime napping and cognitive functioning in chronic fatigue syndrome.

Gotts, Zoe M, Ellis, Jason G, Deary, Vincent et al.·PloS one·2015

This study looked at how sleep patterns, especially daytime napping, affect fatigue, sleepiness, and thinking ability in people with ME/CFS. Researchers asked 118 patients to keep a sleep diary for two weeks and complete daily assessments of their symptoms. They found that afternoon napping was linked to worse cognitive problems and increased daytime sleepiness, suggesting that when and how much patients nap may influence how well they can think and function.

Autonomic Nervous SystemCognitive Impairment

Postural tachycardia syndrome is associated with significant symptoms and functional impairment predominantly affecting young women: a UK perspective.

McDonald, Claire, Koshi, Sharon, Busner, Lorna et al.·BMJ open·2014

This study looked at 136 people in the UK with postural tachycardia syndrome (PoTS)—a condition where your heart rate increases too much when you stand up—and found that it causes serious tiredness and functional problems, especially in young women. The researchers compared two groups of PoTS patients and found their symptoms and quality-of-life impacts were similar to those in people with chronic fatigue syndrome (ME/CFS). Importantly, there was no consistent treatment approach across patients, with some taking no medication and others on different drug combinations.

E2 ModerateBehavioralPEM not requiredCross-Sectional

Characterization of fatigue states in medicine and psychiatry by structured interview.

Bennett, Barbara Kaye, Goldstein, David, Chen, Michelle et al.·Psychosomatic medicine·2014

This study developed and tested a structured interview tool to help doctors better distinguish between different types of fatigue, including ME/CFS, fatigue after cancer treatment, and depression-related fatigue. Researchers interviewed women with different fatigue conditions and found the tool was very accurate at identifying ME/CFS and depression, though less reliable for cancer-related fatigue. The tool may help doctors more accurately diagnose why patients are experiencing fatigue.

DiagnosticsCognitive Impairment

E2 ModerateBehavioralPEM unclearCross-Sectional

Psychosocial factors involved in memory and cognitive failures in people with myalgic encephalomyelitis/chronic fatigue syndrome.

Attree, Elizabeth A, Arroll, Megan A, Dancey, Christine P et al.·Psychology research and behavior management·2014

This study looked at how memory and concentration problems in ME/CFS are connected to emotional and physical factors. Researchers asked 87 people with ME/CFS about their fatigue, mood, anxiety, and support systems, then measured their memory and cognitive problems. They found that fatigue, depression, and a person's sense of personal capability were linked to memory difficulties and thinking problems.