Emotion-processing areas in the brain disrupted during depression

According to neuroscientists, parts of the brain that usually coordinate to process emotion become decoupled in people who experience multiple episodes of depression.

The findings from this study may help identify patients who can benefit from long-term administration of anti-depressants in order to prevent more occurrences of depressive episodes.The study was conducted by a team of researchers in the University of Illinois in Chicago, and is currentlypublished in the journal Psychological Medicine.

Scott Langenecker, associate professor of psychiatry and psychology at UIC and the corresponding authorof the study, says that half of the people who experience a depressive episode for the first time will have another within a span of two years.

Disruptions in regions of the brain that are active at the same time when processing information oremotions have been implicated in a number of mental illnesses, one of which is depression. On the other hand, hyperconnectivity, or too much connection in the resting network, which are the areas that should normally be active during rest and self-reflection, could also cause the same.

If we can identify different network connectivity patterns that are associated with depression, then we may be able to determine which are risk factors for poorer outcomes down the line, such as having multiple episodes, and we can keep those patients on preventive or maintenance medication. We can also start to see what medications work best for people with different connectivity patterns, to develop more personalized treatment plans, says Langenecker.

In a previous research, Langenecker was able to find out that the emotional and cognitive brain networks were hyperconnected in young adults suffering from depression. In the new study, he and his coworkers wanted to check if different patterns of network-disruption would be seen in adolescents who experienced only one episode of depression as compared to those who experienced several.

Decoupling in Depression

The team used functional magnetic resonance imaging (MRI) to scan the brains of participants. A total of 77 young adults with an average age of 21 were involved in the study. Seventeen of the participants were currently experiencing major depression during the time of the study, while 34 were in good condition. Out of these 51 patients, 36 had experienced a minimum of one episode previously, and these patients were compared to 26 other participants who have never experienced depression. None of the participants were taking any form of medication during the course of the study.

The amygdala, a region whose role is to detect emotion, is decoupled from the emotional network in people who have experienced more than one episode of depression. Because of this, emotional information processing would become less accurate and could explain negative processing-bias in which those suffering from depression see neutral information as negative.

This may be an adaptation the brain makes to help regulate emotional biases or rumination. Since this study provides just a snapshot of the brain at one point in time, longer-term studies are needed to determine whether the patterns we saw may be predictive of a future of multiple episodes for some patients and might help us identify who should have maintenance treatments and targets for new preventive treatments, Langernecker says.