Soldiers keep cool in a crisis naturally
Soldiers who perform best under extreme stress might truly be natural born heroes, a study of US military shows.
Dr Deane Aikins, assistant professor of psychiatry at Yale University, says blood analysis of soldiers who remain cool in a crisis show they have higher levels of chemicals that dampen the fear response.
He says the finding could lead to new drugs or training strategies to help others cope better.
Speaking at the annual meeting of the American Association for the Advancement of Science, Aikins says there "are certain individuals who just don't get as stressed".
"Their stress hormones are actually lower. It doesn't reach the same peak as the rest of us," he says.
"So we are ready to scream in our chair, and there are certain individuals who just don't get as stressed. Their stress hormones are actually lower and the peptides that down-regulate that stress are quite higher."
Aikins and colleagues at Yale University studied stress hormone levels of soldiers undergoing survival training, which included mock prisoner of war experiences and interrogation.
Blood samples taken from the soldiers showed those who fared best under extreme stress had lower levels of the stress hormone cortisol and higher levels of neuropeptide y, a chemical that dampens the body's stress response.
Interviews with the soldiers after the exercise showed that while all of them found the experience unpleasant, only those with low cortisol levels said they did not find it particularly distressing.
"All of the recovery hormone systems, all of the systems that turn it down, really kick in for these resilient individuals," Aikins says. "The question is how do you get folks who aren't as cool in stress trained up?"
He says the research suggests "we can start predicting who the individuals are that will have this very unique cooler hormonal profile under high stress".
This could help in pinpointing those returning soldiers most likely to develop post-traumatic stress disorder (PTSD), which the US Department of Defence estimates affects 20% of troops returning from Iraq.
Aikins and colleagues now are studying whether giving other soldiers a dose of this stress-dampening neuropeptide might help people fare better in combat situations.
Factors contribute to traumatic stress
According to Karestan Koenen, a public health professor at Harvard University, although huge numbers of people live through traumas, such as rape, natural disasters or other violent crime, not everyone develops PTSD.
"For example for rape, about 50% of women developed PTSD and why is that? One issue is the severity of the trauma but we also found that early childhood and genetic factors influence who develop PTSD much later in life," she says.
Koenen has been part of a team looking at the predictors of PTSD in a study that has followed a group of New Zealanders from birth to age 30.
They found factors such as a low IQ at age five, difficult temperament at age three and then family environment factors such as growing up in poverty, having a depressed mother, moving often or being separated from parents at a young age could all predispose people to developing the condition.
Also "some people have genetic variants that make them more vulnerable to the effects of trauma", she says.
"[So] basically we know now that PTSD is not just about the trauma, that early child characteristics, family environment and genetic factors influence how people respond to horrible events during their life."