Two regions in the midline of the brain - the medial prefrontal cortex and posterior cingulate cortex - are known for their role in self-awareness, and are often very active when a person’s mind is wandering.
An Orygen study has found that the interaction between these two brain regions is also important when depressed young people think about themselves.
A team led by Associate Professor Christopher Davey found there is abnormal connectivity between these two regions when depressed young people think about themselves, with the medial prefrontal cortex having an unusually high level of influence over the posterior cingulate cortex. This causes the young person to have difficulty shifting their focus to events in the external environment.
“We found that young people with depression appraise themselves more negatively, and that this is related to the greater influence the medial prefrontal cortex has on the posterior cingulate cortex,” Associate Professor Davey said.
“Young people with depression can excessively ruminate about themselves, and this abnormal connectivity explains why they might find it so difficult to concentrate on things happening outside of them,” Associate Professor Davey said.
To measure the connectivity between the two brain regions, the researchers used functional magnetic resonance imaging to study the brains of 159 young people while they undertook tasks related to self-appraisal and external attention. Seventy-one of the young people had moderate-to-severe major depressive disorder while 88 were young people who were not experiencing depression. The abnormal connectivity was observed only in the young people who had major depressive disorder.
The research was published in the American Journal of Psychiatry.