Using functional magnetic resonance imaging (fMRI), the study found that those diagnosed with chronic fatigue syndrome had less activation of the basal ganglia. The reduced basal ganglia activity was also linked with the severity of fatigue symptoms, according to the study.
“We chose the basal ganglia because they are primary targets of inflammation in the brain,” says lead author Andrew Miller, MD, a professor of psychiatry and behavioral sciences at Emory University School of Medicine.
“Results from a number of previous studies suggest that increased inflammation may be a contributing factor to fatigue in CFS patients, and may even be the cause in some patients.”
The basal ganglia are structures deep within the brain, thought to be responsible for the control of movements and responses to rewards, as well as cognitive functions, according to researchers.
In previous published studies by researchers at Emory University, people taking interferon alpha as a treatment for hepatitis C, which can induce severe fatigue, also show reduced activity in the basal ganglia.
Interferon alpha is a protein naturally produced by the body as part of the inflammatory response to viral infection. Inflammation has also been linked to fatigue in other patients, such as breast cancer survivors.
“A number of previous studies have suggested that responses to viruses may underlie some cases of CFS,” Miller said.
“Our data supports the idea that the body’s immune response to viruses could be associated with fatigue by affecting the brain through inflammation. We are continuing to study how inflammation affects the basal ganglia and what effects that has on other brain regions and brain function. These future studies could help inform new treatments.”
“Potential treatments might include medications to alter the body’s immune response by blocking inflammation, or providing drugs that enhance basal ganglia function,” he said.
For the latest study, researchers compared 18 patients diagnosed with chronic fatigue syndrome with 41 healthy volunteers. The 18 patients were recruited based on an initial telephone survey followed by extensive clinical evaluations.
The clinical evaluations, which came in two phases, were completed by hundreds of Georgia residents. People with major depression or who were taking antidepressants were excluded from the imaging study, although those with anxiety disorders were not, according to the researchers.
For the brain imaging portion of the study, the participants were told they’d win a dollar if they correctly guessed whether a preselected card was red or black. After they made a guess, the color of the card was revealed, and at that point researchers measured blood flow to the basal ganglia.
According to the researchers, the key measurement was the size of the difference in activity between a win or a loss.
Scores on a survey gauging levels of fatigue were tied to the difference in basal ganglia activity between winning and losing. Those with the most fatigue had the smallest changes, especially in the right caudate and the right globus pallidus, both parts of the basal ganglia, the study found.
The study was a collaboration among researchers at Emory University School of Medicine, the Center for Disease Control’s Chronic Viral Diseases Branch, and the University of Modena and Reggio Emilia in Italy. Funded by the CDC, the study was published in the journal PLOS One.
Source: Emory Health Sciences