Dr Sigmund Freud, known as the father of psychoanalysis, was the first to claim that crushing guilt is a common symptom of depression. Now, the new research found a communication breakdown between two guilt-associated brain regions in people who have had depression.
This so-called "decoupling" of the regions may be why depressed people take small faux pas as evidence that they are complete failures, the researchers said.
"If brain areas don't communicate well, that would explain why you have the tendency to blame yourself for everything and not be able to tie that into specifics," study researcher Roland Zahn, a neruoscientist at the University of Manchester in the UK, told LiveScience.
For their research, Zahn and his colleagues focused their research on the subgenual cingulated cortex and its adjacent septal region, a region deep in the brain that has been linked to feelings of guilt. Past studies have found abnormalities in this region, dubbed the SCSR, in people with depression.
The SCSR is known to communicate with another brain region, the anterior temporal lobe, which is situated under the side of the skull. The anterior temporal lobe is active during thoughts about morals, including guilt and indignation.
In the study, the researchers used functional magnetic resonance imaging (fMRI) to scan the brains of a group of people after remission from major depression for more than a year, and a control group who have never had depression.
Both groups were asked to imagine acting badly, for example being 'stingy' or 'bossy' towards their best friends. They then reported their feelings to the research team.
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The resulting scans showed that while the SCSR and the anterior temporal lobe activate together in both guilt and indignation in healthy brains, the brains of once-depressed individuals functioned quite differently.
During feelings of indignation, the SCSR-anterior temporal lobe linkage worked fine. But during feelings of guilt, the regions failed to sync up so neatly, the researchers found.
The subjects who were most prone to self-blame showed the greatest communication gaps between these regions, the team reported in journal Archives of General Psychiatry. (More)