Treating the Fear of Gaining Weight in Anorexia Nervosa

Treating the Fear of Gaining Weight. A Randomized Controlled Clinical Trial for Patients With Anorexia Nervosa

The study was terminated with a total of 35 patients finally enrolled, due to the Sars-Cov-2 (COVID-19) global pandemic breakout and the confinement measures considered.

Hospital Sant Joan de Deu, Hospital Clinic of Barcelona, Hospital San Carlos, Madrid, Hospital Universitari de Bellvitge, Istituto Auxologico Italiano

The main aim of this study is to develop a virtual reality (VR) embodiment-based exposure technique to improve the treatment of anorexia nervosa (AN). A systematic and hierarchical body exposure intervention in which the patient owns a virtual avatar is proposed. At first, the virtual body matches with the real measurements of the patient, then the experimenter will progressively increase Body Mass Index (BMI) values of the virtual body during the exposure sessions until a healthy BMI value is reached (e.g. BMI score of 20). In this study a VR embodiment-based technique that combines visuo-motor and a visuo-tactile stimulation procedures is proposed in order to increase illusory feelings of ownership over the virtual body. It is hypothesised that adding a VR-based body exposure intervention to the classical cognitive behavioral therapy (CBT) will significantly reduce symptomatology in AN patients.

In order to evaluate the efficacy of the addition of a VR body exposure component to the usual treatment, a randomized controlled clinical trial will be conducted. 54 patients with a primary diagnosis of anorexia nervosa and a BMI > 18.5 will be randomly assigned to the experimental group receiving VR body exposure in addition to cognitive behavioral therapy or control group, which receives cognitive behavioral therapy only. Data regarding eating disorder symptomatology and body related attention will be collected before and at the end of the intervention, as well as after six months of follow-up. In the systematic and hierarchical VR body exposure intervention, which consists of 5 weekly exposure sessions, patients will gradually be exposed to increases in the BMI of their virtual avatar. Each session starts by inducing illusory feelings of ownership over the virtual body by the means of visuo-tactile and visuo-motor stimulation. Then patients are exposed to their virtual bodies in order to achieve the habituation or extinction of the anxiety response to their body image and, consequently, reduce the fear of gaining weight. During exposure, patients will be asked to focus on different parts of the virtual body, by asking what they think and feel about them. Body ownership illusion, body-related anxiety and fear of gaining weight will be assessed within each session by means of visual analogue scales.

Patients assigned to this group will receive the usual CBT from the clinical unit or the hospital where they are, and additionally, six sessions of VR-based body exposure intervention. In these weekly sessions patients will go through a body exposure intervention in which the they will own a virtual avatar with their real measurements, that will progressively increase its BMI values throughout the following exposure sessions, until a healthy BMI value is reached.

Patients assigned to this group will receive the usual treatment from the centre in which they are recruited for the study (CBT), and will have to complete the evaluations following the same schedule as the experimental group.

Combine usual cognitive-behavioral treatment (CBT) sessions with additional five VR-based body-exposure therapy sessions.

Evaluation of the change in drive for thinness, with maximum possible score of 28, where higher scores indicate higher drive for thinness

Evaluation of the change in body dissatisfaction, with maximum possible score of 40, where higher scores indicate higher body dissatisfaction

Evaluation of the change in body distortion in adolescents using the TSA body distortion scores, which can range from -3 to 3, with higher values indicating higher body distortion

Evaluation of the change in body dissatisfaction in adolescents using the TSA body dissatisfaction scores, which can range from -3 to 3, with lower scores indicating higher body dissatisfaction

Evaluation of the change in body distortion in adults using the BIAS-BD body distortion scores, ranging from -80 to 80, with higher scores indicating higher body distortion

Evaluation of the change in body dissatisfaction in adults using the BIAS-BD body dissatisfaction scores, ranging from -80 to 80, with higher scores indicating higher body dissatisfaction

Evaluation of body-related anxiety using the PASTAS, with a maximum score of 32, with higher scores indicating higher body-related anxiety

Evaluation of the change in body appreciation using the BAS, with a scale of possible scores ranging from 13-65, where higher scores indicate higher body appreciation

Evaluation of the attentional bias towards the body using complete fixation time (evaluated in milliseconds) of the gaze towards weight-related body parts, with higher values indicating a greater attentional bias

Evaluation of the attentional bias towards the body using the number of fixations of the gaze towards weight-related body parts, with higher values indicating a greater attentional bias

Up to 40 minutes. Baseline (prior to beginning the body exposure session), every two minutes during the exposure, and at the end of the body exposure session

Up to 40 minutes. Baseline (prior to beginning the body exposure session) and at the end of the body exposure session

Inclusion Criteria: patients with primary diagnosis of anorexia nervosa (DSM-V) from the age of 14 years with BMI <18.5 Exclusion Criteria: visual deficits epilepsy or neuroleptic medication psychotic disorder bipolar disorder medical complications pregnancy clinical cardiac arrhythmia