While doctors and patients alike have long suspected ties between emotion and inflammatory disease, exactly how the body and brain interact during these illnesses is a mystery. However, researchers recently found parts of the brain that link emotional stress to the symptoms of one ailment: the wheezing, coughing, chest constriction, and labored breathing of an asthma attack.

Scientists found that people suffering from an asthma attack are hypersensitive to asthma-related emotional words, according to a study in this September's issue of Proceedings of the National Academy of Sciences. Using functional magnetic resonance imaging, a procedure that uses magnets to detect brain activity, the researchers found that asthma sufferers' brains respond strongly to words like "wheeze," "cough," and "suffocate" after they inhale allergens such as dust mite or ragweed extract.

Other emotional words, like "loneliness," and neutral words, like "curtains," had no effect. When the patients repeated the same task but inhaled saline or Meth (a drug that causes lung constriction but not inflammation) instead of an allergen, the brain didn't respond as strongly to the emotional words.

The University of Wisconsin researchers pinpointed two regions of the brain that these asthma-related words seem to affect: the anterior cingulate cortex and the insula. Scientists think the anterior cingulate cortex is involved in emotion and pain while the insula links emotions to sensory stimuli.

"The brain really plays a role in the unfolding of asthmatic symptoms. When asthma symptoms occur, they affect a person's emotional state," says Richard Davidson, a doctor and researcher at the University of Wisconsin's Laboratory for Affective Neuroscience. "The brain really needs to be considered part of the equation."

Researchers think that this link between illness and stress may involve glucocorticoids, a class of steroids found in the body that stops an overactive immune system from causing tissue damage. Under psychological stress, immune cells don't respond as readily to glucocorticoids. Drugs like cortisone, one type of glucocorticoid, help reduce inflammation in patients but can cause severe side effects if used too often. Davidson and his colleagues found that glucocorticoids didn't regulate the immune system as effectively in patients who inhaled the allergens.

While the study is small, only six asthma sufferers were tested, scientists say the research could pave the way for the development of drugs and behavior therapies that help control asthma and other stress related diseases.

"I think it's important work," says John Bienenstock, a professor of medicine at the Brain-Body Institute at McMaster University. Bienenstock cites similar experiments that have found links between emotion and gastrointestinal disease. "Neuroscience is finally able to come to bear on the issue of these chronic inflammatory diseases."

Bienenstock says that, while this study looked at how asthma affects emotions, not how stress affects asthma symptoms, researchers think that the relationship works both ways. "The two things are bidirectional," he explains.

Find out more: Check out the U.S. News Allergy & Asthma Center for more information.