Depression very early in life can affect the way a child’s brain develops.
A new study by researchers at Washington University is the first to link early childhood depression to physical changes in the developing brain.
As part of the research, Washington University child psychiatrist Dr. Joan Luby and her colleagues followed the development of approximately 200 St. Louis-area children for up to 11 years, giving them behavioral assessments and a series of three brain scans. About half of the children had episodes of depression, most starting when they were only 3 to 6 years old.
"What we found is that those children who had high levels of depressive symptoms in early childhood had a very different pattern of gray matter brain development through middle childhood and early adolescence," Luby said.
In psychologically healthy children, the outer layer of the brain, known as the cortical gray matter, increases in thickness and volume up through early puberty. At that point, a process known as "pruning" begins, involving the selective elimination of neurons. "So normal gray matter development is characterized by what we call an inverted U-shape curve: it grows to a peak, and then it starts to thin and decrease in volume," Luby said.
The study, published in the journal JAMA Psychiatry, focused on the downward slope of that U-shaped progression. "And what we saw is that kids who had early childhood depression actually had a steeper drop-off in volume and increased thinning [of gray matter] compared to kids who did not have depression," Luby said.
The research team is continuing to study the children as they get older to try to understand the functional effects of those brain differences, but research in adults suggests that gray matter plays a role in regulating emotional responses. "Generally speaking, people who have thicker and bigger volume of gray matter are thought to have better emotion-regulatory capacities," Luby said. "It can also be associated with other things like IQ and cognitive functioning."
Luby said the current study underscores the need to pay attention to depressive episodes in young children. "People walk around thinking that the brain is genetically predetermined to develop in a certain way," Luby said. "But actually your life experiences impact how your brain develops, and that’s important, because that’s something we can control."
There is also evidence that the brain can recover from setbacks, particularly early in life. Luby and her colleagues are now conducting a treatment study for preschool-age children with depression, with the goal of enhancing their mental health and emotional development.
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