Chronic Pain May Depend on Emotional Reaction to Injury

More activity between certain brain regions seems to be linked to lingering problems, research says

MONDAY, July 2 (HealthDay News) -- Whether a person's injury will lead to chronic pain may depend on the level of communication between two parts of their brain, a new study finds.

According to the report, published in the current issue of Nature Neuroscience, brain regions related to emotional and motivational behavior seem to communicate more in those who develop chronic pain.

"For the first time, we can explain why people who may have the exact same initial pain either go on to recover or develop chronic pain," senior study author A. Vania Apkarian, a professor of physiology at Northwestern University Feinberg School of Medicine in Chicago, said in a university news release.

"The injury by itself is not enough to explain the ongoing pain," Apkarian added. "It has to do with the injury combined with the state of the brain."

For the study, the researchers used brain scans to examine interaction between two parts of the brain -- the frontal cortex and the nucleus accumbens -- in 40 patients who had back pain develop recently for the first time. The patients were followed for one year.

By analyzing the scans, the investigators were able to predict whether the patients would develop chronic pain with an 85 percent level of accuracy.

The findings suggest that the brain's emotional reaction to the injury is crucial.

"It may be that these sections of the brain are more excited to begin with in certain individuals, or there may be genetic and environmental influences that predispose these brain regions to interact at an excitable level," Apkarian said. "Now we hope to develop new therapies for treatment based on this finding."

An estimated 30 million to 40 million U.S. adults suffer from chronic pain. Back pain is especially common.

"Chronic pain is one of the most expensive health care conditions in the U.S., yet there still is not a scientifically validated therapy for this condition," Apkarian said.

Although the study showed an association between levels of communication in the brain and chronic pain, it did not prove a cause-and-effect relationship.

More information

For more about chronic pain, visit the U.S. National Library of Medicine.

-- Randy Dotinga

SOURCE: Northwestern University, news release, July 1, 2012

Last Updated: July 02, 2012

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