Studies reviewed in this article include:
1. Study suggests organic brain dysfunction in CFS
2. Researchers find CFS patients don't walk normally
3. Muscle abnormalities in CFS not due to inactivity
4. Selegiline has minor therapeutic effect in CFS
5. Sleep abnormalities and depression in CFS
6. Delayed orthostatic hypotension causes chronic fatigue
7. Blood flow abnormalities in orthostatic intolerance
You can find the abstracts of these articles at the PubMed, a listing of research journal articles maintained by the U.S. National Institutes of Health. Authors, titles, publication information and UI number are included at the end of each summary. You can read the abstracts by going to the PubMed website at http://www.ncbi.nlm.nih.gov/PubMed/ and inserting the UI number of the article into the search window.
For a reliable, professional explanation of these studies, please consult your own doctor.
Researchers studied CFS patients and sedentary controls with tests designed to measure instinctive and learned reaction to sensory stimulation, using sound associated with a puff of air directed toward the eyeball in order to cause the subject to blink. They found that the CFS patients reacted normally to both the sound and the airpuff, but "displayed impaired acquisition of the eyeblink response using a delayed-type conditioning parameter." In other words, the CFS patients reacted normally to the stimuli themselves, but were abnormally slow to learn new reactions to stimuli. What I think this means is that the researchers made the sound and sent the puff of air toward the subject's eye at the same time, and after this was done a few times, normally the subjects should have instinctively learned to blink as soon as they heard the sound; but the CFS patients were not able to do this as a normal person would. The researchers say that this indicates an "associative deficit," and that CFS patients are probably suffering from "organic brain dysfunction within a defined neural substrate."
UI number: 98263991
Authors: Servatius RJ, Tapp WN, Bergen MC, Pollett CA, Drastal SD, Tiersky LA, Desai P, Natelson BH
Title: "Impaired associative learning in chronic fatigue syndrome"
Published: Neuroreport 1998 Apr 20; 9(6):1153-1157
Researchers studied the spatial (movement) and temporal (speed) parameters of gait (walk) of 12 CFS patients. They found significant abnormalities in symmetry, which has to do with the movement of one side of the body as compared to the other, as well as other abnormalities. They also found that these abnormalities did not change from the beginning to the end of the exercise period, and so could not have been produced by fatigue. The authors say that this study strengthens the hypothesis that a dysfunction of the central nervous system plays a part in the onset of CFS.
UI Number: 98202319
Authors: Saggini R, Pizzigallo E, Vecchiet J, Macellari V, Giacomozzi C.
Title: "Alteration of spatial-temporal parameters of gait in chronic fatigue syndrome patients."
Publication: J Neurol Sci 1998 Jan 21; 154(1):18-25.
Researchers used quadriceps needle biopsies to examine the muscles of 105 CFS patients. They wanted to find out if abnormalities could be due to lack of activity. Muscle atrophy from inactivity would have resulted in an increased number of a particular type of muscle fiber, called muscle fiber type 2, as well as fiber atrophy.
The researchers found that muscle fiber type 1, not type 2, was predominant, and that fiber atrophy was only present in ten percent of the patients. This meant that there was no sign of abnormality which could have been due to inactivity. However, they did find that some CFS patients had an abnormal lactate response to exercise, and that these patients had a lower proportion of mitochondria rich type 1 muscle fibers.
UI Number: 98186380
Authors: Lane RJ, Barrett MC, Woodrow D, Moss J, Fletcher R, Archard LC
Title: "Muscle fiber characteristics and lactate responses to exercise in chronic fatigue syndrome."
Published: J Neurol Neurosurg Psychiatry 1998 Mar;64(3):362-367
Researchers studied the effect of Selegiline, a specific monoamine oxidase B receptor inhibitor, against a placebo in 25 CFS patients over a six-week trial period. Patients filled out questionnaires about mood, fatigue, functional status and symptom severity at the beginning of the trial, after two weeks of treatment, and at the end of the trial. They found that the patients who took Selegiline reported significant improvement in tension/anxiety, vigor and sexual relations, and that the drug was not acting as an antidepressant.
UI Number: 98259960
Authors: Natelson BH, Cheu J, Hill N, Bergen M, Korn L, Denny T, Dahl K.
Title: "Single-blind, placebo phase-in trial of two escalating doses of Selegiline in the chronic fatigue syndrome."
Published: Neuropsychobiology 1998;37(3):150-154
Researchers at Dalhousie University in Nova Scotia were interested in the question of why some CFS patients are depressed and some aren't. They gave a group of CFS patients the Diagnostic Interview Schedule to determine which ones had depression and which didn't; then they tested the whole group in a sleep laboratory.
REML, or Rapid Eye Movement Latency, is one possible indicator of depression. The basic idea is that depressed people have shorter periods of REM sleep, or dream sleep. The investigators found that the CFS patients who had depression also had short REML; the CFS patients who did not have depression did not have short REML.
UI number: 98286887
Authors: Morehouse RL, Flanigan M, Macdonald DD, Braha D, Shapiro C
Title: "Depression and short REM latency in subjects with chronic fatigue syndrome."
Published: Psychosom Med 1998 May;60(3):347-351
One of the co-authors of this study, Dr. David Streeten, is also the co-author with Dr. David Bell of the much-discussed study of low blood volume in CFS. In this study, Dr. Streeten and a colleague looked at various neurological and endocrine disorders to see if they can cause fatigue like the fatigue CFS patients feel.
They did this by giving 431 patients who were diagnosed with various neurological or endocrine disorders a questionnaire about fatigue. They found that delayed orthostatic hypotension (a blood pressure disorder involving delayed response to posture changes) and all forms of hypocortisolism (low levels of cortisol) always occurred in patients who said they had symptoms of chronic fatigue. On the other hand, patients with acute orthostatic hypotension (immediate and severe response to posture changes) only had fatigue symptoms some of the time; they were more likely to feel lightheaded or to faint. Patients with multiple system atrophy, pituitary disorders without hypocortisolism, and ideopathic hirsutism did not have chronic fatigue symptoms.
The researchers concluded that delayed orthostatic hypotension and all forms of hypocortisolism produce chronic fatigue.
UI Number: 98273883
Authors: Streeten DH, Anderson GH Jr
Title: "The role of delayed orthostatic hypotension in the pathogenesis of chronic fatigue."
Published: Clin Auton Res 1998 Apri;8(2):119-124
Again, this was not a study of CFS patients in particular, but a study of what orthostatic intolerance (a blood pressure disorder common to CFS patients) can do to blood flow, and how orthostatic intolerance can be predicted using blood flow measures. The researchers attempted to artificially induce orthostatic intolerance in 8 healthy subjects, first by keeping them head-down on a tilt table for 4 days, and then by keeping them confined for 4 days.
They found that the head-down tilt table procedure did induce orthostatic intolerance in their subjects. Then they used echography and doppler technology to study blood flow in their subjects during two orthostatic tests: the tilt table with the person tilted up, and a lower body negative pressure test (LNBP). They found that most of the patients had developed a distended femoral (thigh) superficial vein, and had lowered femoral resistance increase. They concluded that the femoral resistance index and the cerebral to femoral flow ratio as measured by doppler during LNBP were the most reliable predictors for orthostatic intolerance.
The UID number for this study has not been assigned yet, but the PMID number is 9614291.
Authors: Arbeille P, Herault S
Title: "Cardiovascular echographic and doppler parameters for the assessment of orthostatic intolerance."
Published: Eur J Ultrasound 1998 Feb 1;7(1):53-71
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