Tag: reward

Brain imaging reveals clues about chronic fatigue syndrome

A brain imaging study shows that patients with chronic fatigue syndrome may have reduced responses, compared with healthy controls, in a region of the brain connected with fatigue. The findings suggest that chronic fatigue syndrome is associated with changes in the brain involving brain circuits that regulate motor activity and motivation.

Compared with healthy controls, patients with chronic fatigue syndrome had less activation of the basal ganglia, as measured by fMRI (functional magnetic resonance imaging). This reduction of basal ganglia activity was also linked with the severity of fatigue symptoms.

According to the Centers for Disease Control and Prevention, chronic fatigue syndrome is a debilitating and complex disorder characterized by intense fatigue that is not improved by bed rest and that may be worsened by exercise or mental stress.

The results are scheduled for publication in the journal PLOS One.

“We chose the basal ganglia because they are primary targets of inflammation in the brain,” says lead author Andrew Miller, MD. “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.”

Miller is William P. Timmie professor of psychiatry and behavioral sciences at Emory University School of Medicine. The study was a collaboration among researchers at Emory University School of Medicine, the CDC’s Chronic Viral Diseases Branch, and the University of Modena and Reggio Emilia in Italy. The study was funded by the CDC.

The basal ganglia are structures deep within the brain, thought to be responsible for control of movements and responses to rewards as well as cognitive functions. Several neurological disorders involve dysfunction of the basal ganglia, including Parkinson’s disease and Huntington’s disease, for example.

In previous published studies by Emory researchers, 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 groups such as breast cancer survivors.

“A number of previous studies have suggested that responses to viruses may underlie some cases of CFS,” Miller says. “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.”

Treatment implications might include the potential utility of medications to alter the body’s immune response by blocking inflammation, or providing drugs that enhance basal ganglia function, he says.

The researchers compared 18 patients diagnosed with chronic fatigue syndrome with 41 healthy volunteers. The 18 patients were recruited [not referred] 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.

For the brain imaging portion of the study, 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.

The key measurement was: how big is the difference in activity between a win or a loss? Participants’ scores on a survey gauging their 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.

Ongoing studies at Emory are further investigating the impact of inflammation on the basal ganglia, including studies using anti-inflammatory treatments to reduce fatigue and loss of motivation in patients with depression and other disorders with inflammation including cancer.

 

Source: Emory Health Sciences. “Brain imaging reveals clues about chronic fatigue syndrome.” ScienceDaily. ScienceDaily, 23 May 2014. https://www.sciencedaily.com/releases/2014/05/140523192427.htm

 

Chronic fatigue syndrome patients had reduced activity in brain’s ‘reward center’

Chronic fatigue syndrome, a medical disorder characterized by extreme and ongoing fatigue with no other diagnosed cause, remains poorly understood despite decades of scientific study. Although researchers estimate that more than 1 million Americans are affected by this condition, the cause for chronic fatigue syndrome, a definitive way to diagnose it, and even its very existence remain in question. In a new study, researchers have found differing brain responses in people with this condition compared to healthy controls, suggesting an association between a biologic functional response and chronic fatigue syndrome.

The findings show that patients with chronic fatigue syndrome have decreased activation of an area of the brain known as the basal ganglia in response to reward. Additionally, the extent of this lowered activation was associated with each patient’s measured level of fatigue. The basal ganglia are at the base of the brain and are associated with a variety of functions, including motor activity and motivation. Diseases affecting basal ganglia are often associated with fatigue. These results shed more light on this mysterious condition, information that researchers hope may eventually lead to better treatments for chronic fatigue syndrome.

The study was conducted by Elizabeth R. Unger, James F. Jones, and Hao Tian of the Centers for Disease Control and Prevention (CDC), Andrew H. Miller and Daniel F. Drake of Emory University School of Medicine, and Giuseppe Pagnoni of the University of Modena and Reggio Emilia. An abstract of their study entitled, “Decreased Basal Ganglia Activation in Chronic Fatigue Syndrome Subjects is Associated with Increased Fatigue,” will be discussed at the meeting Experimental Biology 2012, being held April 21-25 at the San Diego Convention Center. The abstract is sponsored by the American Society for Investigative Pathology (ASIP), one of six scientific societies sponsoring the conference which last year attracted some 14,000 attendees.

More Fatigue, Less Activation

Dr. Unger says that she and her colleagues became curious about the role of the basal ganglia after previous studies by collaborators at Emory University showed that patients treated with interferon alpha, a common treatment for chronic hepatitis C and several other conditions, often experienced extreme fatigue. Further investigation into this phenomenon showed that basal ganglia activity decreased in patients who received this immune therapy. Since the fatigue induced by interferon alpha shares many characteristics with chronic fatigue syndrome, Unger and her colleagues decided to investigate whether the basal ganglia were also affected in this disorder.

The researchers recruited 18 patients with chronic fatigue syndrome, as well as 41 healthy volunteers with no symptoms of CFS. Each study participant underwent functional magnetic resonance imaging, a brain scan technique that measures activity in various parts of the brain by blood flow, while they played a simple card game meant to stimulate feelings of reward. The participants were each told that they’d win a small amount of money if they correctly guessed whether a preselected card was red or black. After making their choice, they were presented with the card while researchers measured blood flow to the basal ganglia during winning and losing hands.

The researchers showed that patients with chronic fatigue syndrome experienced significantly less change in basal ganglia blood flow between winning and losing than the healthy volunteers. When the researchers looked at scores for the Multidimensional Fatigue Inventory, a survey often used to document fatigue for chronic fatigue syndrome and various other conditions, they also found that the extent of a patient’s fatigue was tightly tied with the change in brain activity between winning and losing. Those with the most fatigue had the smallest change.

Results Suggest Role of Inflammation

Unger notes that the findings add to our understanding of biological factors that may play a role in chronic fatigue syndrome. “Many patients with chronic fatigue syndrome encounter a lot of skepticism about their illness,” she says. “They have difficulty getting their friends, colleagues, coworkers, and even some physicians to understand their illness. These results provide another clue into the biology of chronic fatigue syndrome.”

The study also suggests some areas of further research that could help scientists develop treatments for this condition in the future, she adds. Since the basal ganglia use the chemical dopamine as their major neurotransmitter, dopamine metabolism may play an important role in understanding and changing the course of this illness. Similarly, the difference in basal ganglia activation between the patients and healthy volunteers may be caused by inflammation, a factor now recognized as pivotal in a variety of conditions, ranging from heart disease to cancer.

Estimates from the CDC suggest that annual medical costs associated with chronic fatigue syndrome total about $14 billion in the United States. Annual losses to productivity because of lost work time range between $9 and $37 billion, with costs to individual households ranging between $8,000 and $20,000 per year.

 

Source: Federation of American Societies for Experimental Biology (FASEB). (2012, April 24). Chronic fatigue syndrome patients had reduced activity in brain’s ‘reward center’. ScienceDaily. Retrieved March 4, 2017 from https://www.sciencedaily.com/releases/2012/04/120424142109.htm