Children exposed to community violence may be traumatised up to a year after the event, which may carry long-term negative consequences for health, says a study.
"We know that exposure to violence is linked with aggression, depression, post-traumatic stress symptoms and academic and cognitive difficulties in the short term, but little is known about the long-term effects of such exposure," said Elizabeth Susman, professor biobehavioural health, Penn State University, US.
The scientists from the Penn State and University College London, chose 124 children, aged between eight and 13 years and living in small city and rural communities, to participate in the study, the Journal of Adolescent Health reports.
"We focused on children who live in small towns, so you would normally not expect them to be exposed to a lot of violence. Also, these were healthy children without a history of reported maltreatment," said Melissa Peckins, biobehavioural health graduate student from Penn State.
The researchers gave each of the adolescents a questionnaire, which identified their exposure to violence during lifetime and within the past 12 months, according to a Penn State statement.
The adolescents were then given the beginning of a story and asked to complete it in front of two mock judges, whom they were told were evaluating their responses and performances for later comparison to those of other children the same age.
Following the story-completion task, adolescents were also given a serial subtraction task.
The team measured the children's stress responses by comparing the cortisol levels present in samples of their saliva collected before and after the stress test was administered.
Cortisol is a steroid hormone, produced by adrenal gland and is released in response to stress.
"In males, we found that as exposure to violence increased, cortisol reactivity decreased, so cortisol reactivity was attenuated; it was a habituation effect," Peckins said. The finding was not present in females.
"In enduring stressful conditions, we may have adapted evolutionarily to suppress our cortisol levels because higher and more prolonged levels of cortisol in the bloodstream can lead to negative health consequences, such as autoimmune disorders, lowered immunity, arthritis and atypical depression," Susman said.
This may explain why cortisol reactivity was lower for males," Susman added.
"However, 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.