A Virtual Reality Full Body Illusion Improves Body Image Disturbance in Anorexia Nervosa

TLDR

Anorexia nervosa patients experience persistent distortions in body size perception. The study examined whether a Full Body Illusion could alter body size estimates of emotionally salient body parts in AN. Participants underwent a virtual reality Full Body Illusion with synchronous visuo‑tactile stimulation and reported shoulder, abdomen, and hip size estimates before, immediately after, and at a 2‑hour‑45‑minute follow‑up. AN patients reduced overestimation of shoulders, abdomen, and hips immediately after the FBI, with effects lasting to follow‑up, while healthy controls showed different patterns; the results suggest body‑size distortions in AN are flexible and can be modified, providing a basis for new interventions.

Abstract

Patients with anorexia nervosa (AN) have a persistent distorted experience of the size of their body. Previously we found that the Rubber Hand Illusion improves hand size estimation in this group. Here we investigated whether a Full Body Illusion (FBI) affects body size estimation of body parts more emotionally salient than the hand. In the FBI, analogue to the RHI, participants experience ownership over an entire virtual body in VR after synchronous visuo-tactile stimulation of the actual and virtual body.We asked participants to estimate their body size (shoulders, abdomen, hips) before the FBI was induced, directly after induction and at ~2 hour 45 minutes follow-up. The results showed that AN patients (N = 30) decrease the overestimation of their shoulders, abdomen and hips directly after the FBI was induced. This effect was strongest for estimates of circumference, and also observed in the asynchronous control condition of the illusion. Moreover, at follow-up, the improvements in body size estimation could still be observed in the AN group. Notably, the HC group (N = 29) also showed changes in body size estimation after the FBI, but the effect showed a different pattern than that of the AN group.The results lead us to conclude that the disturbed experience of body size in AN is flexible and can be changed, even for highly emotional body parts. As such this study offers novel starting points from which new interventions for body image disturbance in AN can be developed.