For some time, trauma or maltreatment during childhood has been known to increase one’s risk of developing mental health conditions such as depression later in life. Now, for the first time, researchers have found that these experiences can change specific subregions in the amygdala and the hippocampus.
For the study, the researchers recruited 35 participants with clinically diagnosed major depressive disorder. All were aged between 18 and 49. The researchers also recruited 35 healthy controls, each matched for age, sex and education.
Each participant was then assessed for childhood trauma by answering the Childhood Trauma Questionnaire. They also underwent an MRI scan to measure the volumes of various parts of their hippocampus and amygdala- two parts of the brain that are both heavily involved in the stress response and continue to develop long after birth.
In the end, the researchers found that participants with major depressive disorder and a history of childhood abuse displayed significantly smaller volumes in areas of the hippocampus and their right amygdala. The researchers also noted that major depressive disorder and antidepressant treatments did not affect the volume of different parts of the amygdala.
The findings demonstrate a biological basis for childhood stress affecting brain development. These early effects then may make it harder for people to deal with adult stresses later on, making them more vulnerable to developing depression or other psychiatric disorders.
The researchers also say that their findings may shed some light on how treatments such as psychedelics work to treat various mental health conditions- especially given increasing evidence that they encourage nerve growth in these areas of the brain.
“Understanding the specific structural and neurochemical brain changes that underlie mental health disorders is a crucial step toward developing potential new treatments for these conditions, which have only increased since the onset of the COVID-19 pandemic,” says Peter Silverstone, one of the study’s authors.