Study shows differences in the brain in interpreting physical signals in mental disorders
Researchers have shown why people with mental disorders, including anorexia and panic disorder, perceive physical signals differently.
The University of Cambridge researchers found that the part of the brain that interprets physical signals from the body behaves differently in people with a range of mental disorders, suggesting that it could be a target for future treatments.
The researchers examined “interoception” – the ability to sense internal states in the body – and whether there were common differences in the brain in people with mental disorders during this process. They found that a region of the brain called the dorsal central island showed varying levels of activity during interoception in a number of disorders, including depression, schizophrenia, eating disorders, and anxiety disorders.
Many people with mental disorders experience physical symptoms differently, be it an uncomfortable feeling of fullness with anorexia or the feeling of not having enough air with a panic disorder.
The results, reported in The American Journal of Psychiatry, show that activity in the dorsal center island could fuel these diverse interpretations of body sensations in mental health. Being more aware of the differences in the way people experience physical symptoms could also be helpful for those treating mental disorders.
We all use exteroception – seeing, smelling, hearing, tasting and feeling – to control our daily life. But interoception – the ability to interpret signals from our body – is essential for survival, even if this often happens unconsciously.
“Interoception is something we all do all the time, although we may not be aware of it,” said lead author Dr. Camilla Nord from the MRC Department of Cognitive and Brain Sciences. “For example, most of us are able to interpret the signals of low blood sugar like tiredness or irritability and know what to eat. However, there are differences in how our brain interprets these signals. ”
Differences in interoceptive processes have already been noted in people with eating disorders, anxiety and depression, panic disorders, addictions and other mental disorders. Theoretical models have shown that impaired cortical processing drives these changes in interoceptive processing and imparts susceptibility to a range of mental health symptoms.
Nord and her colleagues combined brain imaging data from previous studies and compared the differences in brain activity during interoception between 626 patients with mental disorders and 610 healthy controls. “We wanted to find out whether something similar was happening in the brain in people with different mental disorders, regardless of their diagnosis,” she says.
Their analysis showed that in patients with bipolar disorder, anxiety, major depression, anorexia, and schizophrenia, a part of the cerebral cortex called the dorsal central island showed a different brain activation in processing pain, hunger and other interoceptive signals compared to the control group.
The researchers then performed a follow-up analysis and found that the dorsal center island did not overlap with regions of the brain that were altered by antidepressants or psychological therapy, suggesting that it could be studied as a new target for future therapeutics in differences treat interoception.
“It is surprising that, despite the variety of psychological symptoms, there seems to be a common factor in how physical signals in mental disorders are processed differently by the brain,” said Nord. “It shows how closely physical and mental health are intertwined, but also the limits of our diagnostic system – some important factors of mental health could be ‘transdiagnostic’, that is, occur in many diagnoses.”
For the future, Dr. Nord studies to test whether this impaired activation could be changed by new treatments for mental disorders, such as brain stimulation.
The research was supported by the NIHR Cambridge Biomedical Research Center.
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