Researchers from the Washington University School of Medicine found brains of clinically depressed preschoolers develop abnormally. The findings were compared to the brains of young children unaffected by clinical depression.
Among preschoolers diagnosed with clinical depression, the brain's gray matter has lower volume and thinner cortex. Gray matter refers to the tissue that links brain cells and carries signals across. Gray matter is involved in memory, hearing, seeing, emotion and decision-making processes. Cortex is a vital brain part that processes emotions.
"What is noteworthy about these findings is that we are able to see how a life experience - such as an episode of depression - can change the brain's anatomy," said the study's first author Dr. Joan L. Luby, whose work showed clinical depression can be established in young children at the age of three.
The research team analyzed 193 children wherein 90 have been diagnosed with clinical depression during preschool years. As the children aged, the team conducted clinical tests and MRI scans.
The initial MRI scan was conducted when the kids were between the ages of six and eight, while the final scans were taken between ages 12 and 15. About 116 children enrolled underwent three brain scans in the course of the study.
"If we had only scanned them at one age or stage, we wouldn't know whether these effects simply were present from birth or reflected an actual change in brain development," said study co-investigator Dr. Deanna M. Barch, head of the Department of Psychological and Brain Sciences in Arts & Sciences at Washington University.
The MRI scans done in multiple stages enabled the team to monitor the brain's maturing process and the changes clinical depression imprinted. Gray matter's amount increases in a normal brain growth. Gray matter begins to decline starting puberty when neuron's communication become more efficient.
In the study, the brains of clinically depressed kids revealed a higher decrease in gray matter. The severity of the child's clinical depression was also associated with the severity of brain tissue's volume and thickness loss.
In the MRI scans of children whose parents suffered depression, gray matter showed normal development except when the child itself is clinically depressed. The study can help analyze why clinically depressed children have troubles in handling their emotions and moods.
The findings were published in the journal JAMA Psychiatry on Dec. 16.
