A new UK study suggests depression weakens neural connections in specific brain networks.
Investigators used functional magnetic resonance imaging (brain scans) to scan the brain activity in 39 depressed people (23 female 16 male) and 37 control subjects who were not depressed (14 female 23 male).
The researchers found the fMRI scans revealed significant differences in the brain circuitry of the two groups.
Among depressed patients, the greatest difference was the reduced connection of the so-called “hate circuit” involving brain regions of the superior frontal gyrus, insula and putamen.
According to lead researcher Jianfeng Feng, Ph.D., the hate circuit was first clearly identified in 2008 by Semir Zeki, Ph.D., who found that a circuit which seemed to connect three regions in the brain (the superior frontal gyrus, insula and putamen) when test subjects were shown pictures of people they hated.
Researchers also discovered the brains of depressed people had altered activity in response to risks and actions, reward and emotion, attention and memory processing.
Among the depressed group:
•The hate circuits were 92 percent likely to be weakened;
•The risk/action circuit was 92 percent likely to be weakened;
•The emotion/reward circuit was 82 percent likely to be weakened.
“The results are clear but at first sight are puzzling as we know that depression is often characterized by intense self loathing and there is no obvious indication that depressives are less prone to hate others,” Feng said.
“One possibility is that the uncoupling of this hate circuit could be associated with impaired ability to control and learn from social or other situations which provoke feelings of hate towards self or others. This in turn could lead to an inability to deal appropriately with feelings of hate and an increased likelihood of both uncontrolled self-loathing and withdrawal from social interactions.
“It may be that this is a neurological indication that it is more normal to have occasion to hate others rather than hate ourselves.”
As in many aspects of medical research, additional studies are required to improve analysis and interpretation.
The study is published in the journal Molecular Psychiatry.
Source: University of Warwick