Virtual reality & body experience in eating disorders

Anorexia Nervosa (AN) is one of the most invasive psychosomatic disorders with
a relatively high mortality rate. In order to ensure successful treatment it is
crucial to understand the underlying mechanisms of AN. One of the central
symptoms of AN is a disturbed experience of the own body. To date, not all
aspects of this so-called body image disturbance have been investigated fully.
Though, research shows that body image disturbances appear to be the key to
full recovery of AN. Therefore in the current study we will focus on
multisensory input and body size experience.
In one of our previous studies we have found that AN patients overestimate the
size of their body compared to healthy controls. After providing participants
with multisensory input as part of the Rubber Hand Illusion, AN patients*
overestimation of body size decreased (i.e. was more accurate). It appears that
multisensory stimulation contributes to changed (more accurate) body size
experience in AN.
In our previous study we focused on size experience of the hand only. In the
current study we aim to investigate whether multisensory input also affects
body size estimation of a more clinically relevant body part. Therefore we will
focus here on size experience of the abdomen before and after multisensory
stimulation.

The main objective of the current study is investigating whether AN patients
and healthy controls differ in how they experience (estimate) the size of their
abdomen before and after multisensory input is provided (we will compare size
estimation errors before and after providing multisensory input between the
patient and healthy control group).

A first secondary objective of the current study is investigating whether they
way in which multisensory input is provided affects the change in body size
experience we expect to find in the AN group. Multisensory stimulation can take
place in a synchronous fashion (visual and tactile input are provided
simultaneously) or in a asynchronous fashion (visual and tactile input are not
aligned).
A second secondary objective of the curren study is investigating whether
changes in body size experience in the AN group are persistent over tie. Two
hours after multisensory stimulation took place, we will again ask participants
to estimate their body size.

Quasi-experimental

It is not expected, but theoretically possible that the participants experience
negative emotions during the study, for example due to tactile stimulation on
the abdomen (note that tactile input is provided with a soft brush). However,
the chance of experiencing negative emotions is thought to be minimal, since
before participation takes place the participants will be informed of the
procedures during the study and what will happen during the experiment. From
experience with previous (AN) studies we learned that participants understand
why certain methods are important for the study, and that explaining these
methods to the participants reduces concerns. In addition, the knowledge that
will be gained in the current study will not only increase our understanding of
body representation disturbances in AN, but will might have implication for
treatment of AN.