(MCT) -- MILWAUKEE - A team of University of Wisconsin-Madison researchers has shown that chronic stress of poverty, neglect and physical abuse in early life may shrink the parts of a child's developing brain responsible for memory, learning and processing emotion.
While early-life stress already has been linked to depression, anxiety, heart disease, cancer and a lack of educational and employment success, researchers have long been seeking to understand what part of the brain is affected by stress to help guide interventions.
The UW research recently published in the journal Biological Psychiatry adds to a growing body of research linking chronic stress early in life to brain development. The research focused on two brain regions - the hippocampus and amygdala - that are involved in memory, learning and processing emotion.
Findings from other researchers have been mixed, which the UW researchers believe may be attributed to automated software being used for brain measurements. The automated software may be prone to error because the brain regions are so small, according to the UW researchers.
Seth Pollak, co-leader of the study and a UW professor of psychology, identifies families from all over Wisconsin who are interested in participating in studies at the UW's Waisman Center. Pollack is the center's director.
For the UW study, Pollack's team recruited 128 children around age 12 and divided them into four groups after extensive interviews with the children and their caregivers, documenting behavioral problems and their cumulative life stress.
One group had experienced physical abuse, another group was neglected before being adopted from a foreign country, and a third group came from low socioeconomic status households. The fourth group of children came from middle-class households and had not experienced any of the three types of chronic, early stress.
Researchers did MRI scans of the children's brains, focusing on the hippocampus and amygdala. Then they painstakingly traced those regions of the brain by hand on paper.
The tracing of brain regions alone took about two years, according to the study's lead author and recent UW PhD graduate Jamie Hanson.
"The regions are very small," he said. "If you include even a little of one region that shouldn't be there, it skews the results."
The hand measurements showed that children who had experienced poverty, neglect or physical abuse had a smaller amygdala and hippocampus than the children from middle-class households with no chronic stress, Hanson said.
"I think we added something substantive to the literature," he said. "This is a good snapshot into the brain."
Why early-life stress may shrink brain structures is unknown, according to Hanson, now a postdoctoral researcher at Duke University's Laboratory for NeuroGenetics.
That question will require researchers to delve deeper into the circuitry of the brain and how regions of the brain interact at the moment a child is exposed to stress. An abused child seeing an image of an angry adult face, for example, Hanson said.
The research may inform social policy and interventions to help vulnerable children, Hanson said.
"The brain isn't destiny and a lot can be changed," he said. "We want to give every child the best start."
In fact, the brain is changeable and treatable through exercise, medication and cognitive therapy, Hanson said.
Not everyone who experiences chronic early stress has negative outcomes, Hanson noted.
"We can think about lots of people who overcome adversity," he said. "I look at our research as showing a probability. You may have a greater risk, but it's not 100 percent."
Insurance companies figured out long before scientists that the brain is still changing and developing in early adulthood, Hanson said.
"That's why they require you to be 25 years old to rent a car," he said.