"There has been a lot of work on animals linking both acute and chronic stress to changes in a part of the brain called the prefrontal cortex, which is involved in complex cognitive abilities like holding on to important information for quick recall and use," says study co-author Jamie Hanson of Wisconsin-Madison, US.
"We have now found similar associations in humans. More exposure to stress is related to more issues with certain kinds of cognitive processes," adds Hanson, the Journal of Neuroscience reports.
Children who had experienced more intense and lasting stressful events posted lower scores on tests of what researchers refer to as spatial working memory.
They had more trouble navigating tests of short-term memory such as finding a token in a series of boxes, according to the study, a Wisconsin statement says.
Brain scans revealed that the anterior cingulate, a portion of the prefrontal cortex believed to play key roles in spatial working memory, takes up less space in children with greater exposure to very stressful situations.
"These are subtle differences, but differences related to important cognitive abilities," says Hanson.
But these may not be irreversible differences. "We're not trying to argue that stress permanently scars your brain. We don't know if and how it is that stress affects the brain," says Hanson, a psychology graduate student at Wisconsin-Madison.
"We only have a snapshot — one MRI scan of each subject — and at this point we don't understand whether this is just a delay in development or a lasting difference," Hanson adds.
"It could be that, because the brains is very plastic, very able to change, that children who have experienced a great deal of stress catch up in these areas," says Hanson.
Researchers determined stress levels through interviews with children aged nine to 14 years and their parents.
The team, which included Wisconsin psychology professors Richard Davidson and Seth Pollak and their labs, collected expansive biographies of stressful events from slight to severe.