INTEROCEPTION: the process by which the nervous system senses, interprets, and integrates cascades of these signals from within the body in order to maintain homeostasis.1
INTEROCEPTION AWARENESS: the act of consciously sensing, interpreting, and integrating information about the state of inner body systems.
More than two-thirds of patients with eating disorders also have comorbid mood and anxiety disorders.2 This suggests that the current system of symptom-based diagnosis incompletely identifies the underlying pathophysiological mechanisms driving these illnesses. This article considers how a transdiagnostic process called interoception may help to advance our understanding and treatment of eating disorders.
Overview of interoception
Consider for a moment the fact that every day our brains interpret sensory signals from the body in order to keep us out of harm’s way. The most common form of these signals relates to our ability to see predators looming in the distance, to hear them creeping up in the shadows, or to perhaps simply smell and avoid a poisonous piece of food. While the visual, auditory, and olfactory systems are clearly critical for survival, our brains are also constantly tracking a completely different world of sensory signals—ones originating from within our bodies.
Interoceptive sensory signals arising from the gastrointestinal, cardiovascular, respiratory, urogenital, hormonal, osmotic, glycemic, and acidotic systems are each in their own way critical to survival. What would happen if you were unable to sense when your blood sugar was low—how would you know whether you were hungry? Would you rely on others to notice a change in your behavior, such as irritability? If you were alone, would you suffer in silence? How would you survive? What if you could not detect the feeling of thirst? Sensing whether it is time to eat, drink, sleep, or excrete waste are daily rhythms that we engage in almost unconsciously. But not so for patients with eating disorders. Disrupted interoceptive awareness may negatively impact the mental health of individuals affected by eating disorders.
Interoception in anorexia nervosa
Individuals with anorexia nervosa (AN) display a remarkable ability to ignore hunger cues and to maintain the body in a state of self-starvation, despite clamorous signaling from peripheral orexigenic hormones such as ghrelin.3 Contrary to usual settings, the corrective action of eating is experienced aversively by these patients, as evidenced by the fact that they report heightened fears at the prospect of eating a meal and assiduously avoid situations involving food.4 Individuals with AN show a dysfunctional processing of interoceptive signals during premeal periods, as evidenced by a heightened experience of sympathetically mediated symptoms such as palpitations and dyspnea.5 They also show abnormal brain activity in areas important for interoceptive processing.
Acutely underweight patients show reduced functional connectivity in a brain network centered around the insular cortex, a region that is the primary cortical recipient of interoceptive signals relayed through the brainstem and thalamus.6 Weight restored patients exhibit greater insula activation in association with stomach sensations, but the opposite relationship happens in the amygdala, highlighting the potential role of negative affect in the body sensing process.7
Dr Khalsa is Director of Clinical Studies, Laureate Institute for Brain Research, University of Tulsa, Tulsa, OK. Dr Khalsa reports no conflicts of interest concerning the subject matter of this article.
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