Attenuation of self-produced touch in the posterior insula reflects body image disturbances in anorexia nervosa

Body image disturbance (BID) is a core feature of anorexia nervosa (AN), encompassing multimodal distortions in bodily self-perception. Affective touch, a gentle, emotionally salient tactile stimulus, is implicated in body ownership but has not been extensively studied in AN. Affective touch is processed in the insula, an area involved in interoception and bodily self-awareness which has been shown to be altered both structurally and functionally in AN.

This study explored the neural mechanisms underlying BID by examining how individuals with AN process self-produced affective touch. Women with AN (n = 44) and age-matched healthy controls (HC, n = 40), participated in a self-other-object touch task during functional brain imaging and filled out questionnaires related to body image and eating disorder symptomatology. During self-touch, individuals with AN exhibited increased activation in the right posterior insula compared to object-touch, whereas HC did not.

This insular activation correlated positively with body attitude (BAT) and body size estimation (FRS) scores in AN, but negatively in healthy controls, suggesting divergent processing of self-related tactile input. These findings suggest that posterior insular responses to self-produced touch may reflect disturbed sensory self-processing in AN, and that touch-based mechanisms contributing to body ownership in healthy individuals may operate differently in the context of AN. Broadening BID research beyond the visual modality opens new avenues for translational research and treatment.

This research was funded by grants from the Swedish Medical Research Council (2015-02684) to HO, from ALF, Region Östergötland (RÖ-702221; RÖ-837632; RÖ-893981; RÖ-940701) to MZ, from the Swedish Society of Medicine (SLS-784151; SLS-960468; SLS-878101) to MZ and RB, and from Lions Forskningsfond (liu-2019-01191) to RB. We thank Lisa Engberg and Anna Elander for help with patient recruitment, and Adam Enmalm for help with data collection. Department of Biomedical and Clinical Sciences, Center for Social and Affective Neuroscience, Linköping University, S-581 83, Linköping, Sweden Morgan Frost-Karlsson, Maria Zetterqvist, Håkan Olausson & Rebecca Boehme Clinical Department of Child and Adolescent Psychiatry in Linköping, Region Östergötland, Linköping, Sweden Department of Clinical Neurophysiology, Linköping University Hospital, 58185, Linköping, Sweden Center for Medical Imaging and Visualization, Linköping University, 58185, Linköping, Sweden Correspondence to Morgan Frost-Karlsson.

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