People with major depressive disorder may have faulty neural processing of “gut feelings”, such as hunger or fullness, called gastric interoception. Previous studies have shown that interoception (how we sense feelings within our body) is reduced in people with depression, but new brain scans are highlighting how the circuitry involved in these gut feelings may be altered in people with repetitive negative thoughts.
“Repetitive negative thinking (RNT), usually referred to as ‘rumination’ in persons who suffer from depression, is a very significant clinical problem,” said author Salvador M. Guinjoan in a statement to PsyPost.
“The reason is that when it is severe and persistent, RNT conditions higher chances of depression relapse and is associated with residual symptoms after treatment, is more common in persons who do not respond to treatment, and is even related to suicide. This particular communication refers to one among a series of projects in our lab attempting to understand rumination.”
Interoception can be considered a sixth sense, in a way – your body is constantly monitoring your internals for whether you are hungry, thirsty, need the toilet, and more. It’s a vital part of keeping your body happy, and disruptions can be debilitating.
Previous studies have found that faulty interoception could be involved with how people with depression generally get lower learning outcomes, but it was unclear whether this was the case or how it could be happening.
The focus is particularly on RNT – people with high rumination often dwell on their shortcomings, may have low self-esteem due to negative thoughts about themselves, and generally recall negative aspects of their life.
In this study, the researchers took a cohort of 48 people with depression who had high RNT scores and 49 people with depression who scored low, as well as a healthy cohort of 27 people for a control group.
Participants were asked to feel sensations coming from their heart and stomach while scientists looked at their brains through functional magnetic resonance imaging scans. This way, they could track how healthy people and how people with high RNT differ in the way they use their brains while being interoceptive.
All depressed people had reduced processing of signals coming from their stomach, and this happened across multiple regions of the brain. What was highly interesting, however, was how people with high rumination had an even greater reduction in processing from the stomach, which was particularly focused around emotion and memory processing regions of the brain.
These findings could help explain why highly ruminative people often report abdominal problems, as signals from the stomach are not processed in the typical way. The researchers hope more investigation into this area can be conducted so that it could help improve treatment outcomes in patients with high RNT scores.
The study was published in the Journal of Psychiatric Research.