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Response to stress said linked with a chemical

CHICAGO - A mechanism in the brain may explain why some people keep their cool and others crumble under stress, US researchers said yesterday.

"We have identified the ways in which the brain naturally copes with chronic stressful experiences," said Dr. Vaishnav Krishnan of the University of Texas Southwestern Medical Center, whose study appears in the journal Cell.

Psychologists have long understood that some people are more vulnerable than others to stress, which can lead to depression and even post-traumatic stress disorder. Krishnan and colleagues set out to study this problem in mice that were exposed to stress.

They found that the mice most vulnerable to stress had too much of a chemical, brain-derived neurotrophic factor, or BDNF, in a region of the brain that processes reward signals.

And they found a significant increase in this same chemical in humans with depression.

It turns out that resilient mice produce a kind of protective response that allows them to recover from stress. Vulnerable mice lack this defense.

The researchers said the finding might help lead to new therapies that build up resiliency in people.

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