Understanding the Fatigue of Multiple Sclerosis
Excessive tiredness may be linked to extensive brain nerve fiber damage
TUESDAY, Feb. 17, 2004 (HealthDayNews) -- Widespread nerve fiber damage in the brains of people with multiple sclerosis (MS) is associated with serious fatigue, says a Canadian study in the February issue of the Archives of Neurology.
The study included 60 people with MS who were grouped as having low fatigue (26 people) or high fatigue (34 people) based on their responses to a questionnaire on fatigue, which affects about 87 percent of people with MS.
The biological causes of this fatigue are unknown. Some experts believe it may be caused by widespread axonal (nerve fiber) damage associated with MS.
The researchers used magnetic resonance spectroscopy to measure the N-acetylaspartate/creatine ratio (NAA/Cr) of these two naturally occurring brain chemicals. This ratio is an indicator of proper nerve functioning. A higher NAA/Cr ratio indicates better nerve functioning in the brains of people with MS.
The study found the people in the high fatigue group had a significantly lower NAA/Cr ratio, an indication of more nerve fiber damage and poorer nerve functioning.
"Our observations, combined with those of others, suggest that widespread axonal dysfunction is associated with fatigue in MS," the study authors write.
"It may be hypothesized that diffuse white matter (brain) disease translates into an increase in the central nervous system effort required by a patient with MS to perform the same activity as compared with a disease-free subject, with resultant fatigue."
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