Following recovery these individuals exhibit hyperactivation in the insular cortex during the anticipation and resolution of restricted breathing loads (dyspnea) but, surprisingly, not during the loads themselves.8 Patients also abnormally classify taste stimuli—AN and bulimia nervosa patients have reduced insula responses to ingested glucose.9
Taken together, these findings support the general hypothesis that patients with AN make erroneous inferences about internal body sensations in context-specific (eg, food-related) settings. These somatic errors may be key drivers of anxiety expression in the disorder. As clinicians, we can learn much about how these individuals perceive the world by studying the way their brains actively infer meaning about missing or ambiguously perceived interoceptive signals.10
Interoception in bulimia nervosa and binge eating disorder
Interoceptive dysfunction plays an important role in the periods of uncontrolled and disproportionate food ingestion that characterize binge eating, as well as the periods of expulsion that characterize purging. Gastric capacity appears to be increased in bulimia nervosa, and patients with binge eating disorder demonstrate larger meal intake and lower plasma ghrelin than non-binge eaters.11 These findings suggest physical alterations of the gastrointestinal system in both disorders.
Abnormalities of interoceptive processing have been suggested at the neural level in bulimia nervosa, but methodological differences in the available studies limit firm conclusions.12 Even less is known about the effects of purging behaviors on interoception. Further tests that modulate gastrointestinal physiology and measure perceptual responses are needed to improve our understanding of the role of interoception in these disorders.
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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