Both children and soldiers become increasingly aware of potential threats.
The long-term impact for children may be a higher susceptibility to mental health problems, according to experts from University College London (UCL) and the Anna Freud Centre.
It is already known that abused children or those who witness domestic violence are at greater risk of anxiety and depression in later life.
"We are only now beginning to understand how child abuse influences functioning of the brain's emotional systems," lead author Dr Eamon McCrory, from UCL's Division of Psychology and Language Sciences told the journal, Current Biology.
"This research is important because it provides our first clues as to how regions in the child's brain may adapt to early experiences of abuse in the home.
"Enhanced reactivity to a biologically salient threat cue such as anger may represent an adaptive response for these children in the short term, helping keep them out of danger. However, it may also constitute an underlying neurobiological risk factor increasing their vulnerability to later mental health problems, and particularly anxiety.
"The next step for us is to try and understand how stable these changes are. Not every child exposed to family violence will go on to develop a mental health problem; many bounce back and lead successful lives. We want to know much more about those mechanisms that help some children become resilient."
The scientists carried out out magnetic resonance imaging brain scans on 20 London children with an average age of 12 who had been exposed to violence at home, and who had all been referred to local social services.
While in the scanner, the children were shown pictures of male and female faces with sad, calm or angry expressions. Their patterns of brain activity were compared with those of 23 matched children with no history of family violence.
The brains of children exposed to violence responded in a distinct way to angry faces.
Previous research has shown a similar pattern in the brains of soldiers exposed to violence combat situations.
The scans suggest both combat veteran soldiers and children who witness violence tune their brains to be hyper-aware of danger around them.
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