Stress may affect brain development in children, according to researchers at the University of Wisconsin-Madison.
The researchers note there has been a lot of work in animals linking stress to changes in the prefrontal cortex, which is involved in complex cognitive abilities.
“We have now found similar associations in humans, and found that more exposure to stress is related to more issues with certain kinds of cognitive processes,” said Jamie Hanson, a UW-Madison psychology graduate student.
Children who experienced more intense and lasting stressful events posted lower scores on tests of spatial working memory, the researchers said. The children had more trouble navigating tests of short-term memory, such as finding a token in a series of boxes, according to the study, which was published in the Journal of Neuroscience.
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 who have been exposed to very stressful situations.
“These are subtle differences, but differences related to important cognitive abilities,” Hanson said, adding the differences may not be irreversible.
“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,” he said. “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. It could be that, because the brain is very plastic, very able to change, that children who have experienced a great deal of stress catch up in these areas.”
The researchers determined stress levels through interviews with children between the ages of 9 and 14 and their parents. The research team looked at a range of stressors, from slight to severe, Hanson said.
“We wanted to know as much as we could, and then use all this information to get an idea of how challenging and chronic and intense each experience was for the child,” he said.
The researchers, whose work was funded by the National Institutes of Health, also took note of changes in white and gray matter. According to Hanson, white matter connects separate parts of the brain so they can share information, while gray matter “does the math. It takes care of the processing, using the information that gets shared along the white matter connections.”
Early in development gray matter appears to enable flexibility, allowing children to excel at many different activities. But as kids age, gray matter thins. It begins to be “pruned” after puberty, while the amount of white matter grows into adulthood, he says.
“For both gray and white matter, we actually see smaller volumes associated with high stress,” Hanson said, noting this is something that needs to be studied over a long period of time. “Understanding how these areas change can give you a better picture of whether this is just a delay in development or more lasting.”
More study could also show the researchers how to help children who have experienced an inordinate amount of stress.
“There are groups around the country doing working memory interventions to try to train or retrain people on this particular cognitive ability and improve performance,” Hanson said. “Understanding if and how stress affects these processes could help us know whether there may be similar interventions that could aid children living in stressful conditions, and how this may affect the brain.”
Source: University of Wisconsin-Madison