Elizabeth Susman of Pennsylvania State University and colleagues at the University College London, recruited 124 adolescents, ages 8-13, living in small city and rural communities -- children not normally expected to be exposed to a lot of violence. These were healthy children without a history of reported maltreatment.
The researchers identified the study subjects' lifetime exposure to violence and exposure within the previous 12 months.
The adolescents were given a stressful task and then asked to perform a serial subtraction task.
"The task and mental arithmetic task are commonly used to elicit a stress response in laboratory settings," Melissa Peckins, a graduate student, said.
The team measured the children's stress responses by comparing the cortisol -- stress hormone -- levels present in samples of their saliva collected before and after the stress test was administered.
The study, published in the Journal of Adolescent Health, found as exposure to violence increased in males, cortisol reactivity decreased, so cortisol reactivity was attenuated. However, this finding was not present in females.
There is a theory that females may react to stressful situations by talking about it, which may be their way of reducing the negative effects of cortisol in the bloodstream, Susman said.