A mechanism in the brain may explain why some people keep their cool and others crumble under stress, U.S. researchers said on Thursday.
"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.
But little is known about mechanisms in the brain that explain this vulnerability.
Krishnan and colleagues set out to study this problem in mice that were exposed to stress.
What they found was mice that were most vulnerable to stress had too much of a chemical 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. ( Reuters )