Rachel Chason

USATODAY

A new study reveals why some people handle stress better than others.

Researchers say a specific electrical pattern in the brain of otherwise genetically identical mice can predict how well they will cope with stress. This means scientists might eventually be able to prevent people prone to stress from developing post-traumatic stress disorder, depression and other psychiatric disorders that result from chronic stress.

"This is a real smoking gun," said senior author Kafui Dzirasa, a professor of psychiatry and behavioral sciences at Duke University Medical Center. "If we can predict who is more likely to have a hard time handling stress – whether it's a 15-year-old or a soldier going into battle – then we'll be able to warn them and offer preventative treatment."

The study was published Tuesday in the journal Nature Communications.

Dzirasa's team studied the interaction between the amygdala and the prefrontal cortex – two areas of the brain that determine fear and stress responses in mice and men.

They planted hair-sized electrodes in the mice's brains to analyze the level of interaction between the amygdala and prefrontal cortex both before and after being exposed to stress.

That stress came in the form of other, more aggressive mice 50% larger than the test mice.

In a situation that Dzirasa said loosely mimicked human bullying, the researchers put a test mouse in a cage with the aggressor mouse and let it be harassed by the larger mouse for five minutes. Then, they had it live next to its aggressor for the next 23 hours 55 minutes and repeated the same situation with a new aggressor mouse for 15 days.

The mice who were most sensitive to the chronic stress showed higher levels of activation of their prefrontal cortex-amygdala circuit, compared with the more resilient mice.

Dzirasa said it was both "surprising and very exciting" that the same mice who handled the 15 days of stress poorly had also exhibited higher levels of activation of their prefrontal cortex-amygdala circuit before they were chronically stressed.

He said this higher level of activation was apparent after the very first time the mice were exposed to the dangerous behavior.

"We figured out that this one signature determines why otherwise genetically identical mice respond differently to stress," Dzirasa said. "Because we've identified that signature, we can start examining possible treatments."

Eric Nestler, a neuroscience professor at Mount Sinai Hospital in New York, s​aid Dzirasa's paper is the first to look at how different areas of the brain interact when exposed to stressful situations.

"It provides insight into the kinds of changes we would like to institute to either treat depression, or make people resilient so they wouldn't get depressed in the first place," Nestler said.