Early childhood depression alters brain development

http://www.eurekalert.org/pub_releases/2015-12/wuso-ecd121515.php

Public Release: 16-Dec-2015
Early childhood depression alters brain development
Washington University School of Medicine

The brains of children who suffer clinical depression as preschoolers develop abnormally, compared with the brains of preschoolers unaffected by the disorder, according to new research at Washington University School of Medicine in St. Louis.

Their gray matter -- tissue that connects brain cells and carries signals between those cells and is involved in seeing, hearing, memory, decision-making and emotion -- is lower in volume and thinner in the cortex, a part of the brain important in the processing of emotions.

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"Traditionally, we have thought about the brain as an organ that develops in a predetermined way, but our research is showing that actual experience -- including negative moods, exposure to poverty, and a lack of parental support and nurturing -- have a material impact on brain growth and development."

The findings may help explain why children and others who are depressed have difficulty regulating their moods and emotions. The research builds on earlier work by Luby's group that detailed other differences in the brains of depressed children.

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The gray matter is made up mainly of neurons, along with axons that extend from brain cells to carry signals. The gray matter processes information, and as children get older, they develop more of it. Beginning around puberty, the amount of gray matter begins to decline as communication between neurons gets more efficient and redundant processes are eliminated.

"Gray matter development follows an inverted U-shaped curve," Luby said. "As children develop normally, they get more and more gray matter until puberty, but then a process called pruning begins, and unnecessary cells die off. But our study showed a much steeper drop-off, possibly due to pruning, in the kids who had been depressed than in healthy children."

Further, the steepness of the drop-off in the volume and thickness of the brain tissue correlated with the severity of depression: The more depressed a child was, the more severe the loss in volume and thickness.

The researchers determined that having depression was a key factor in gray matter development. In scans of children whose parents had suffered from depression -- meaning the kids would be at higher risk -- gray matter appeared normal unless the kids had suffered from depression, too.

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