Symptoms of anorexia are affected by differences in the mid-insula.
Many people with mental health disorders experience physical symptoms differently, whether this is feeling uncomfortably full in AN or having a strong sense of lack of oxygen during a panic attack. These symptoms are associated with differences in function within the dorsal mid-insula of the brain, according to a research team at the University of Cambridge, England (Am J Psychiatry. 2021.178:761). Identifying these differences in the brain may be important for future treatment designs for persons with eating disorders.
Introception and internal conditions
Exteroception, or the senses of sight, smell, hearing, taste and touch, is readily apparent. In contrast, introception, sometimes called “the hidden sense,” is the body’s ability to sense internal conditions, and is not outwardly apparent. For example, in interoception, the brain models events occurring inside the body, such as a gurgling stomach, tightness in the chest, and even the beating of the heart. It also models other sensations from movements that we cannot feel.
A team led by Dr. Camilla L. Nord has found differences in activity in the dorsal mid-insula of the brain in a range of disorders, including depression, schizophrenia, eating disorders, and anxiety disorders.
Dr. Nord and her colleagues recently reported that individuals with disorders such as depression and eating disorders showed different brain activity from healthy individuals during interoception. Her group conducted a meta-analysis of neuroimaging studies comparing patients with psychiatric disorders with healthy control subjects, in an attempt to identify which brain regions showed convergent disrupted activation during interception. Data from 33 studies were extracted for analysis for this analysis; the study included 610 controls and 626 patients with schizophrenia, bipolar or unipolar depression, substance use disorders, anxiety, eating disorders, and other conditions. Alterations in left dorsal mid-insular activation were seen. Interestingly, the authors note that the dorsal mid-insula does not overlap with other regions of the brain that are altered by antidepressants or brain regions change by psychological therapy.
Thus, this area might be a new target for future therapy. The researchers are planning studies to determine whether the disrupted activation in this area could be altered by new treatments, such as brain stimulation.
These are relevant findings for the ED field. People with AN often seem to have vastly different internal experiences; these results seem to identify a neural underpinning for this phenomenon.