How depression disrupts processing emotions

Regions of the brain that normally work together to process emotion become decoupled in people who experience multiple episodes of depression, a study has found. The findings would help identify which patient would benefit from long term anti-depressant treatment to prevent the recurrence of depressive episodes.

"Half of the people who have a first depressive episode will go on to have another within two years," said study co-author, Scott Langenecker. Disruptions in the network of areas of the brain that are simultaneously active during problem-solving and emotional processing have been implicated in several mental illnesses, including depression.

In addition, "hyperconnectivity" or too much connection within the "resting network" or areas active during rest and self-reflection has also been linked to depression. The study, led by researchers at the University of Illinois at Chicago in the US, was published in the journal Psychological Medicine.

"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," Langenecker explained.

In this study, researchers wanted to see if different patterns of network-disruption would show up in young adults who had experienced only one episode of depression versus several episodes. The researchers used functional magnetic resonance imaging, fMRI scans in a resting state -- to show which areas of the brain are most synchronously active as one relaxes and lets their mind wander.

None were taking psychiatric medication at the time they were scanned. The researchers found that the amygdala, a region involved in detecting emotion, is decoupled from the emotional network in people who have had multiple episodes of depression. This may cause emotional-information processing to be less accurate, Langenecker said.

The researchers also saw that participants who had had at least one prior depressive episode -- whether or not they were depressed at the time of the scan -- exhibited increased connectivity between the resting and cognitive networks.