Depressed individuals who experience intense distress show abnormalities in the neural processing of gastric interoception
Major depressive disorder is associated with altered interoception — or the ability to sense the internal state of your body. Now, new brain imaging research provides evidence that depressed individuals tend to exhibit “wrong” neural processing of gastric interoception, particularly among those with high levels of rumination. The findings were published in Journal of Psychiatric Research.
“Repetitive negative thinking (RNT), commonly referred to as ‘rumination’ in individuals suffering from depression, is a very significant clinical problem,” explained study author Salvador M. Guinjoan, principal investigator at Laureate Institute for Brain Research and Associate Professor at the University of Oklahoma Health Sciences Center in Tulsa.
“The reason is that when it is severe and persistent, RNT leads to a higher chance of depression relapse and is associated with residual symptoms after treatment, is more common in people who do not respond to treatment, and is even associated with suicide. This particular communication relates to one of a series of projects in our laboratory that attempt to understand rumination.”
“In a previous paper, we reported the fact that high rumination is associated with poor emotional learning abilities,” Guinjoan said. “One possible mechanism for this to happen is that interoceptive feedback (ie, information from the body that conveys emotion) was out of whack in people with depression.”
The study included 48 depressed individuals who scored high on the Ruminant Response Scale and 49 depressed individuals who scored low on the scale. People who score high on the scale report that they often engage in various types of rumination, such as thinking about their shortcomings, thinking about how lonely they feel, and thinking, “Why do I always react this way?” The researchers also recruited 27 healthy volunteers, who served as a control group.
To assess the neural correlates of interoceptive awareness, participants were instructed to selectively attend to sensations originating in their heart and stomach, while researchers used functional magnetic resonance imaging technology to monitor their brain activity.
Compared to controls, depressed individuals showed reduced central processing of gastric interoceptive information in several brain regions, including the left medial frontal region and insular cortex, perirhinal cortex, and caudate nucleus. This was true regardless of ruminant levels.
However, depressed individuals with high levels of rumination additionally showed reduced processing of stomach sensations in the hippocampus, amygdala, and entorhinal cortex. These brain regions play a key role in memory, emotional information processing and perception.
“We observed that people with depression have problems with the central processing of interoceptive information coming from the gut in particular, compared to a greater tendency to ruminate,” Guinjoan told PsyPost. “We hypothesize that in this setting, interoceptive information provides insufficient or erroneous feedback on emotion perception and learning, and this in turn may prevent a severely depressed person from ending their repetitive, negatively burdened thoughts.”
The researchers were surprised to find that abnormalities in the neural processing of interoception were limited to the stomach.
“We kind of expected that the interoceptive abnormalities would be more pronounced in the heart area,” Guinjoan explained. “But it turned out that the interception from the stomach is more endangered. In retrospect, this makes sense because so many people with depression actually have symptoms related to the abdomen, including patients who see a primary care physician or gastroenterologist for their abdominal complaints. On the other hand, people with anxiety seem to focus more on the cardiovascular system.”
The study, “Weakened interoceptive processing in persons with major depressive disorder and frequently repeated negative thinking“, by ny Heekyeong Park, Stella M. Sanchez, Rayus Kuplicki, Aki Tsuchiyagaito, Sahib S. Khalsa, Martin P. Paulus, and Salvador M. Guinjoan.