Evidence browser

Sympathetic overactivity in subjects complaining of unexplained fatigue.

Pagani, M, Lucini, D, Mela, G S et al.·Clinical science (London, England : 1979)·1994

This study examined how the nervous system controls heart rate in people with unexplained fatigue compared to healthy people. Using heart rate recordings, researchers found that fatigue patients showed an imbalance in their autonomic nervous system—specifically, the part that triggers the "fight or flight" response was overactive while the calming part was underactive, even at rest.

Autonomic Nervous System

Alpha-delta sleep in patients with a chief complaint of chronic fatigue.

Manu, P, Lane, T J, Matthews, D A et al.·Southern medical journal·1994

This study looked at sleep patterns in 30 patients with chronic fatigue to understand what might be causing their exhaustion. Researchers found that a specific type of abnormal sleep pattern called 'alpha-delta sleep' appeared in about 26% of patients, but it was not clearly linked to ME/CFS or fibromyalgia. The study also found that one-third of the patients had other primary sleep disorders like sleep apnea that may have been contributing to their fatigue.

Sleep

E2 ModerateCohortPEM not requiredObservational

Single fibre EMG studies in chronic fatigue syndrome: a reappraisal.

Roberts, L, Byrne, E·Journal of neurology, neurosurgery, and psychiatry·1994

Researchers used a specialized test called single fibre EMG to examine how well the muscles and nerves work together in people with ME/CFS. They tested 30 patients with ME/CFS and compared them to 30 healthy controls. While they found some minor differences, the differences were so small that the researchers concluded problems with nerve-muscle communication are unlikely to be a main cause of ME/CFS.

Clinical studies with the NOVA ISE for IMg2+.

Altura, B T, Burack, J L, Cracco, R Q et al.·Scandinavian journal of clinical and laboratory investigation. Supplementum·1994

Researchers used a specialized test to measure magnesium levels in the blood of people with various conditions, including ME/CFS. The study found that many conditions like migraines, diabetes, and asthma showed low levels of a specific form of magnesium, but interestingly, people with ME/CFS did not show these same magnesium changes. This suggests that magnesium abnormalities may not be a key feature of ME/CFS.

E2 ModerateCohortPEM unclearLongitudinal

A four-year follow-up study in fibromyalgia. Relationship to chronic fatigue syndrome.

Nørregaard, J, Bülow, P M, Prescott, E et al.·Scandinavian journal of rheumatology·1993

This study followed 91 fibromyalgia patients for about 4 years to see if their muscle pain was caused by other medical conditions and how their symptoms changed over time. Most patients reported their pain got worse, and while many experienced severe fatigue, very few actually met the diagnostic criteria for chronic fatigue syndrome. The good news was that muscle strength remained stable and most cases of fibromyalgia were not caused by an underlying disease.

E2 ModerateCohortPEM unclearLongitudinal

[Chronic fatigue syndrome].

Fucíková, T, Petanová, J·Vnitrni lekarstvi·1993

Researchers followed 52 ME/CFS patients for 1 to 14 years to see how they progressed over time. About 20% recovered completely, about 32% improved significantly, and about 15% developed thyroiditis (thyroid inflammation). The treatments used were mainly immune-modulating drugs chosen based on each patient's individual immune test results, though the benefits were only partial.

Immune System

E2 ModerateCohortPEM unclearCase-Control

Persistence of enterovirus RNA in muscle biopsy samples suggests that some cases of chronic fatigue syndrome result from a previous, inflammatory viral myopathy.

Bowles, N E, Bayston, T A, Zhang, H Y et al.·Journal of medicine·1993

Researchers tested muscle samples from people with post-viral fatigue syndrome (a condition similar to ME/CFS that develops after a viral infection) and found evidence of enterovirus RNA in about 26% of samples. This was much higher than in healthy control samples. The study suggests that some cases of ME/CFS may develop after a viral infection causes inflammation in the muscles, similar to how viral heart infections can lead to long-term heart problems.

E2 ModerateCohortPEM not requiredCase-Control

Assessment of a retrovirus sequence and other possible risk factors for the chronic fatigue syndrome in adults.

Khan, A S, Heneine, W M, Chapman, L E et al.·Annals of internal medicine·1993

Researchers tested whether a virus called HTLV-II might be a cause of ME/CFS by comparing blood samples from 21 people with CFS to 21 healthy controls. They found no trace of the HTLV-II virus in any of the participants, and found no differences between the two groups in exposure to activities that spread viruses. This study argues against the idea that HTLV-II is linked to ME/CFS.

E2 ModerateCohortPEM unclearCross-Sectional

Japanese patients with chronic fatigue syndrome are negative for known retrovirus infections.

Honda, M, Kitamura, K, Nakasone, T et al.·Microbiology and immunology·1993

This study tested 30 Japanese patients with ME/CFS to see if they had been infected with certain viruses called retroviruses, which some researchers thought might cause the illness. Using multiple testing methods, the researchers found that none of the patients had these viral infections. This suggests that these particular known viruses are not responsible for causing ME/CFS in this Japanese patient population.

The overdiagnosis of Lyme disease.

Steere, A C, Taylor, E, McHugh, G L et al.·JAMA·1993

This study looked at 788 people referred to a Lyme disease clinic who were thought to have Lyme disease. Researchers found that only 23% actually had active Lyme disease, while 57% did not have Lyme disease at all—many of these patients had chronic fatigue syndrome or fibromyalgia instead. The main problem was that patients were being incorrectly diagnosed with Lyme disease and given antibiotics that didn't help because they didn't actually have the infection.

E2 ModerateCohortPEM not requiredObservational

Repetitively negative changing T waves at 24-h electrocardiographic monitors in patients with the chronic fatigue syndrome. Left ventricular dysfunction in a cohort.

Lerner, A M, Lawrie, C, Dworkin, H S·Chest·1993

This study looked at heart activity recorded over 24 hours in ME/CFS patients compared to others. All 24 ME/CFS patients showed unusual patterns on their heart monitors (abnormal T waves), compared to only 22% of people without ME/CFS. Further testing found that 8 out of 60 ME/CFS patients had mild heart pumping problems that only showed up during exercise, even though their resting heart function appeared normal. The researchers suggest ME/CFS fatigue might be related to the heart not working well during normal daily activities.

Post-Exertional Malaise

Epidemiology of chronic fatigue syndrome: the Centers for Disease Control Study.

Gunn, W J, Connell, D B, Randall, B·Ciba Foundation symposium·1993

Between 1989 and 1991, the CDC tracked patients with chronic fatigue syndrome across four U.S. cities to understand how common the illness is and who gets it. Researchers found that only about 1 in 4 patients referred to them actually met the strict diagnostic criteria for CFS, while others had different medical conditions or psychiatric histories that might explain their fatigue. The study estimated that CFS affects roughly 2–11 people per 100,000 in the general population, and it most commonly affected women in their 30s.

Fatigue, depression, and social adjustment in chronic fatigue syndrome.

Walford, G A, Nelson, W M, McCluskey, D R·Archives of disease in childhood·1993

This study looked at 12 children with ME/CFS and compared them to children with cystic fibrosis and healthy children. Children with ME/CFS reported much higher levels of tiredness affecting both body and mind, and many showed signs of depression. Their schooling and social lives were seriously disrupted by the illness.

E2 ModerateCohortPEM not requiredCase-Control

Human herpesvirus 6 and chronic fatigue syndrome.

Eymard, D, Lebel, F, Miller, M et al.·The Canadian journal of infectious diseases = Journal canadien des maladies infectieuses·1993

This study compared antibody levels against human herpesvirus 6 (HHV-6) in two groups: people with ME/CFS and people with chronic fatigue who didn't meet the official ME/CFS diagnosis. Researchers found that people with ME/CFS had significantly higher antibody levels against HHV-6, suggesting the virus might play a role in the condition. The study also found that sore throat, headache, and recurrent fatigue were more common in the ME/CFS group.

Immune System

E2 ModerateCohortPEM unclearCross-Sectional

Quality of attention in chronic fatigue syndrome: subjective reports of everyday attention and cognitive difficulty, and performance on tasks of focused attention.

Ray, C, Phillips, L, Weir, W R·The British journal of clinical psychology·1993

Many people with ME/CFS report problems with attention and concentration in daily life. This study compared ME/CFS patients with healthy people using questionnaires about attention problems and computer-based attention tests. Patients reported significantly more attention difficulties than controls, though standard attention tests didn't show clear differences. Interestingly, patients were slower at processing tasks like reading words and naming colors, suggesting their thinking speed may be affected rather than their ability to focus.

Prevalence of fatigue and chronic fatigue syndrome in a primary care practice.

Bates, D W, Schmitt, W, Buchwald, D et al.·Archives of internal medicine·1993

This study looked at how common severe, long-lasting fatigue is in a primary care doctor's office and how often it is ME/CFS. Researchers found that while about 27% of patients had long-term fatigue affecting their daily life, most could be explained by other medical or mental health conditions. Only about 0.3% to 1% of patients actually had ME/CFS, depending on which diagnostic criteria were used.

E2 ModerateBehavioralPEM not requiredCross-Sectional

Chronic fatigue and chronic fatigue syndrome: clinical epidemiology and aetiological classification.

Manu, P, Lane, T J, Matthews, D A·Ciba Foundation symposium·1993

This study looked at 405 patients who came to a hospital complaining of chronic fatigue and tried to figure out what was causing it. Doctors found that most patients had psychiatric conditions like depression or anxiety rather than physical diseases. About 30% of patients met the definition for ME/CFS, and these patients were more likely to attribute their illness to a viral infection than other fatigued patients.

E2 ModerateCohortPEM unclearCase-Control

Information processing efficiency in chronic fatigue syndrome and multiple sclerosis.

DeLuca, J, Johnson, S K, Natelson, B H·Archives of neurology·1993

This study compared thinking and concentration abilities in people with ME/CFS, people with multiple sclerosis (MS), and healthy volunteers. All participants were matched by age and education level. People with ME/CFS and MS both showed difficulty with tasks requiring fast, complex thinking compared to healthy controls, suggesting that ME/CFS may affect how the brain processes information.

A brief mental fatigue questionnaire.

Bentall, R P, Wood, G C, Marrinan, T et al.·The British journal of clinical psychology·1993

Researchers created a short questionnaire to measure mental tiredness and tested it in people with ME/CFS, depression, recovered ME/CFS, muscle disease, and healthy people. The questionnaire worked well at identifying mental fatigue, but it could not tell the difference between people with ME/CFS and people with depression—both groups reported similar types and amounts of mental tiredness.

E2 ModerateCohortPEM not requiredCase-Control

A controlled study of brain magnetic resonance imaging in patients with the chronic fatigue syndrome.

Natelson, B H, Cohen, J M, Brassloff, I et al.·Journal of the neurological sciences·1993

Researchers compared brain scans (MRIs) of 52 people with ME/CFS to 52 similar healthy people. They found that ME/CFS patients were much more likely to have abnormal brain scans—27% compared to only 2% in the control group. The abnormalities included areas of white matter changes and some brain tissue enlargement, though the researchers noted that some of these findings might actually indicate other medical conditions rather than ME/CFS itself.