York* *(May 15, 2009)*
NewYork-Presbyterian scientist Dikoma C. Shungu,
collaborating with other researchers in a new study to develop a
method to diagnose patients with chronic fatigue syndrome (CFS). Earlier
diagnosis can lead to earlier intervention and a more effective course of
Chronic Fatigue Syndrome: From "Yuppie Flu" to Recognized Diagnosis
Doctors sometimes find it difficult to diagnose CFS because there is no one
definitive test, and because CFS shares symptoms with a number of other
conditions including diabetes, thyroid disease, depression, anxiety, and
substance abuse. The disease was not so long ago dismissed as the "yuppie
flu," but it has gradually gained legitimacy and is now accepted as an
established diagnosis. The Centers for Disease Control (CDC) developed a set
of diagnostic criteria in 1994, and the agency has started tracking cases
and reports that as many as 4 million Americans suffer from CFS.
Dr. Shungu's earlier research, published in the October 2008 issue of NMR in
Biomedicine, revealed that patients with CFS often have elevated levels of
lactate in their cerebrospinal fluid, the fluid that bathes the brain.
Lactate is a type of salt that the body produces when there is increased
demand for energy to power certain body functions and oxygen levels are low
– during intense exercise, for example.
Understanding the Connection Between Chronic Fatigue Syndrome and Lactate
Chronic fatigue syndrome often develops on the heels of flu-like illness
from which the patient does not really recover, said Dr. Shungu. "They
remain sick and start feeling very, very tired." The illness may set in
motion a chain of events, he explained: As the body works to fight off the
infection and attempts to neutralize viruses and bacteria, the immune system
forms highly reactive molecules called free radicals. These molecules
sometimes accumulate in such high numbers that they create a destructive
process called oxidative stress, which targets and destroys the
mitochondria, the cellular "engine" that processes oxygen and generates
energy for cell function. When these can no longer produce cellular energy,
an alternate energy-production process kicks in called glycolysis – "and the
end product of glycolysis is lactate, also called lactic acid, which is what
we're detecting," Dr. Shungu said.
Another theory is that damage to the mitochondria may be due to low levels
of oxygen in the brain, Dr. Shungu said. Mitochondria require a minimum
amount of oxygen to operate, if oxygen levels dip, the mitochondria cannot
product energy efficiently so glycolysis kicks in, and lactic acid is
produced. "Preliminary studies have shown that brain blood flow is decreased
in CFS compared to the other groups, which might be a cause for the
increased lactate," said Dr. Shungu.
Dr. Shungu's New Study for Chronic Fatigue Research
Dr. Shungu's new study, sponsored by the Chronic Fatigue and Immune
Dysfunction Syndrome (CFIDS) Association of America, will attempt to better
understand what is happening within the brains and bodies of patients with
CFS – what mechanical processes are taking place that lead to elevated
lactate levels. In this study – as he did in his earlier work – Dr. Shungu
will employ a technology known as magnetic resonance spectroscopy. This
imaging test reveals the chemical composition of tissues in the body such as
the brain. The researchers will observe markers of oxidative stress,
mitochondrial dysfunction and cerebral blood flow.
This study will also have much narrower parameters than the previous one.
Dr. Shungu's earlier study showed levels of lactate that varied considerably
among the CFS patients in the study. "We actually had a very big spread –
more than half of them had significantly increased lactate, but there were
also patients who didn't have increased lactate." This is consistent with
CFS, he said, which is a "very, very heterogeneous, multisystem condition."
This study will compare patients with similar symptoms and should make it
easier for researchers to draw conclusions about the mechanisms that link
CFS with elevated levels of lactate.
*Faculty Contributing to this Article:*
*Dikoma C. Shungu,
Ph.D. http://www.med.cornell.edu/research/dcshungu/index.html is a
Professor of Physics in Radiology at Weill Cornell Medical College,
of the affiliate medical colleges of NewYork-Presbyterian Hospital.*