Stress in early childhood is associated with subtle differences in brain structure that can have significant negative effects on behavior, health, and other aspects of later life, according to a new study led by University of Wisconsin-Madison researchers.
The differences in the size of the hippocampus and amygdala were so small that the researchers had to hand-trace around the structures in images of children’s brains in order to measure them. Automated software measurements did not detect the differences.
The study involved 128 children around age 12 who had undergone physical abuse or neglect early in life or who came from households with low socioeconomic status. Researchers extensively interviewed the children and their caregivers, looking particularly for behavioral problems and cumulative life stress. They also did brain scans, focusing on the hippocampus and amygdala, which are involved in emotion and stress processing. The scans were compared to those of children from middle-class households who had not been mistreated.
Seth D. Pollak, PhD, a professor of psychology at Wisconsin and director of the university’s Child Emotion Lab, is co–senior author of an article about the research published online recently in Biological Psychiatry. In a university news release, he explained the impetus behind the research:
We haven’t really understood why things that happen when you’re 2, 3, 4 years old stay with you and have a lasting impact.
Large amounts of stress early in life have been associated with depression, anxiety, heart disease, cancer, and a lack of success in education and employment, he said. “Given how costly these early stressful experiences are for society, … unless we understand what part of the brain is affected, we won’t be able to tailor something to do about it.”
The researchers’ hand-taken measurements found that children who had experienced physical abuse, neglect, or poverty had slightly smaller amygdalas than those who had not. Children who had experienced physical abuse or poverty also had slightly smaller hippocamus volumes. Children who had current behavioral problems and increased cumulative life stress also had smaller volumes of both brain regions.
“For me, it’s an important reminder that as a society we need to attend to the types of experiences children are having,” Dr. Pollak said. “We are shaping the people these individuals will become.”
However, Jamie L. Hanson, PhD, lead author of the article and a Wisconsin doctoral graduate who is now a postdoctoral researcher at Duke University’s Laboratory for NeuroGenetics, urged caution about making too much of the findings. “Just because it’s in the brain,” he said, “doesn’t mean it’s destiny.”
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