Brain Activity May Play Role in Asthma

When an asthma attack occurs, words like "wheeze" may boost brain activity linked to inflammation, scientists report.

They write that their small study may offer new clues about inflammatory conditions like asthma and could lead to new treatments.

"The data suggest potential future targets for the development of drugs and behavioral interventions to control asthma and other stress-responsive disorders," says researcher Richard Davidson, PhD, in a news release.

Davidson is a psychology and psychiatry professor at the University of Wisconsin-Madison. He directs the university's Laboratory for Affective Neuroscience and the Waisman Laboratory for Brain Imaging and Behavior.

The study appears in the Proceedings of the National Academy of Sciences.

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Stress-Asthma Link

"Asthma, like many inflammatory disorders, is affected by psychological stress," write the researchers. But tracing emotions' route through the brain has been tricky.

Davidson's study included six people with mild allergic asthma. According to the American Academy of Asthma Allergy & Immunology, mild persistent asthmatics have symptoms more than twice a week, but less than once a day. Mild intermittent asthmatics have symptoms no more than twice a week.

Participants inhaled extracts of dust mites or ragweed for the study.

Meanwhile, participants' lung function was monitored using special breathing tests. Their brains were also scanned with functional magnetic resonance imaging (fMRI).

As their asthma kicked into gear, participants viewed words on a computer screen. Some words, like "wheeze," were related to asthma. Others, such as "loneliness," were negative but not specifically about asthma. Neutral words, such as "curtains," were also shown.

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Brain-Body Link

When the asthma-related words were shown, three things happened:

—Two brain areas showed increased activity.

—Lung function worsened during breathing tests.

—Inflammation increased.

Negative or neutral words didn't show the same pattern.

The two brain regions are involved in monitoring the body's internal state and processing emotions.

In asthmatics, the two brain regions may be hyper-responsive to emotional and physiological signals, like inflammation, which may in turn influence the severity of symptoms, says Davidson.

"While this study was small, it shows how important specific brain circuits can be in modulating inflammation," says Davidson.

However, with such a small study it is difficult to weigh the impact of the findings, the researchers write. Larger studies are necessary in order to place any significant impact on the findings.

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By Miranda Hitti, reviewed by Louise Chang, MD

SOURCES: Rosenkranz, M. Proceedings of the National Academy of Sciences, Aug. 29, 2005; online early edition. News release, University of Wisconsin-Madison. News release, Proceedings of the National Academy of Sciences. American Academy of Asthma Allergy & Immunology web site.