Virtual Reality-Based Attention Bias Modification Training for Anorexia Nervosa

Anorexia Nervosa (AN) is considered as one of the most severe subtypes of eating disorders (ED), with important medical complications, high mortality rates, and high comorbidity with other disorders, such as anxiety disorders. Likewise, to what happens in anxiety disorders, several studies have suggested the presence of dysfunctional body-related Attentional Bias (AB) in patients with ED and, specifically, in AN patients. Patients with AN tend to focus their attention on their body, in a dysfunctional way, by showing body checking behaviors, and scrutinizing their general appearance and weight-related body parts. This body-related AB has been associated with higher levels of body dissatisfaction, one of the most important risk factors for the development and maintenance of ED. In addition, body-related AB may be responsible for decreasing the effectiveness of body exposure-based treatments used in patients with AN. For this reason, it is necessary to develop new treatment techniques by adding specific components that aim to reduce body-related AB. It has been proposed to include AB modification techniques within the body exposure therapy, as an effective treatment to reduce body-related AB, body dissatisfaction, and body anxiety. To date, our group has been the first, to use a combination of virtual reality (VR) and eye-tracking (ET) techniques to assess the presence of a body-related AB in non-clinical samples. In order to improve AN-based treatments, this project aims to develop a new AB modification procedure, using ET and VR technologies. In addition, this project aims to integrate this AB modification procedure as a part of a body exposure-based treatment that aims to reduce the fear of weight gain experienced by patients with AN. Finally, this project aims to assess whether adding two separate components of body exposure-based therapy and AB modification training would result in a more effective intervention. It is expected that adding a specific component of VR body exposure procedure in the usual treatment for AN, enhanced through the illusion of ownership toward the virtual body, will result in more effective treatment. In addition, it is expected that adding an AB modification training in the body-exposure-based procedure, will result in a further increase the effectiveness of the treatment.

In a phenomenon known as attentional bias (AB), described as the propensity to pay more attention to certain types of stimuli or information (e.g., disorder-relevant information) over other sorts of information (Williamson et al., 2004), adult and young patients with Anorexia Nervosa (AN) show a tendency to focus more on self-reported unattractive body parts than other body parts (Jansen, Nederkoorn, \& Mulkens, 2005; Tuschen-Caffier et al., 2015; Bauer et al., 2017). Dysfunctional body-related AB presumably maintains body image disturbances, usually reported by patients with AN, by processing only body information that is consistent with dysfunctional cognitive schema content (such as, I am getting a fatter belly), while schema-inconsistent information (e.g., I am getting thinner) is not equally noticed or processed, usually being visually neglected (Rodgers \& DuBois, 2016; Williamson et al., 2004).

Dysfunctional body-related AB may be responsible for decreasing the effectiveness of body exposure-based treatments used in patients with AN. For this reason, it is necessary to develop new treatment techniques by adding specific components that aim to reduce the body-related AB. In a previous project conducted by our group, preliminary evidence was found in favor of a body-related AB modification among patients with AN, after a Virtual Reality (VR)-based mirror-exposure intervention. A key aspect to understand these results might rely on the procedure conducted, in which, patients had to focus on different parts of the virtual body (from the head to the shoes) and were asked to orally express what they though and felt about those body areas.

The current project aims to go further, and includes AB modification techniques within the body exposure therapy, as an effective treatment to reduce body-related AB, body dissatisfaction and body anxiety among patients with AN. To the date, our group has been the first, to use a combination of virtual reality (VR) and eye-tracking (ET) techniques to assess the presence of a body-related AB in clinical and non-clinical samples. Specifically, this project aims to assess whether adding two separate components of body exposure-based therapy and AB modification training would result in a more effective intervention. It is expected that, adding an AB modification training in the body-exposure based procedure (experimental group), will further increase the effectiveness of the treatment compared with the treatment as usual (control group). Specifically, after comparing measures before and after the treatment, it is expected that patients at the experimental group would show a significant increase in BMI values, and a significant reduction of other AN symptomatology (e.g., fear of gaining weight, body image disturbances) and body-related AB, compared to the group control. Likewise, it is expected that these changes will be maintained at the follow-up after six-month.

The project will be conducted at the VR-PSY Lab, University of Barcelona, and the Eating Disorders Units of the Hospital Sant Joan de Déu of Barcelona and Hospital de Bellvitge.

Patients with AN will be exposed to immersive virtual using a VR head mounted display (HTC-PRO Eye) with a precise ET included. In addition to the two controllers that HTC-PRO usually provides, three additional body trackers will be used to achieve full body motion tracking. The virtual environment will consist in a room with a large mirror on the front wall. The mirror will be large enough to reflect every limb of the body and will be placed 1.5 m in front of the patients. A young female avatar wearing a basic white t-shirt with blue jeans and black trainers will be created.

Regarding the treatment, all sessions will last approximately one hour and will take place once a week. All sessions will start by inducing the FBI and assessing the VASs. Exposure treatment on the body will start with a virtual body with the same BMI as the patient. The AB modification training will be based on an adaptation of the AB induction procedure proposed by Smeets, Jansen and Roefs (2011). The training will be developed through the visual selection of geometric figures (e.g. square, rectangle, circle) that fit approximately with specific parts of the body. Each of these figures can have different colors. Specifically, the patient must detect and identify the figures that will appear in different parts of the avatar's body (figure 2). In half of the trials, the shape of the figure must be discriminated and in the remaining 50%, the discrimination will be based on color. Throughout training, the geometric figures will appear on weight-related body parts in 45% of the trials, and in another 45% of the trials it will appear on non-weight-related body parts. In the remaining trials (10%), the test will appear on one of three neutral stimuli located next to the avatar.

ET raw data will be transformed into suitable quantitative data using the Ogama (Open Gaze Mouse Analyzer) software. Previously weight-and non-weight related areas of interest (AOIs) will be defined. Weight-related AOIs will be defined based on the weight scale of body items from the PASTAS questionnaire (Reed, Thompson, Brannick, \& Sacoo, 1991) and drawn onto a picture of a female avatar in a frontal view. Body parts included in the W-AOIs will be the legs, thighs, buttocks, hips, stomach (abdomen) and waist. After the separation of the weight-related-AOIs, the remaining body parts (head, neck, chest, shoulders, arms, and feet) will be labeled as non-weight-related AOIs. Participants' selective visual attention will be measured using the complete fixation time and number of fixations on the areas of interest (AOIs).

Eligibility Criteria:
Inclusion Criteria:

* Patients with a primary diagnosis of anorexia nervosa (DSM-V)
* from the age of 14 years
* with BMI \<18.5
* subsyndromal patients will also be included, understood as those patients who fulfill all the criteria of anorexia nervosa with the exception of two at most

Exclusion Criteria:

* visual deficits
* epilepsy or neuroleptic medication
* psychotic disorder
* bipolar disorder
* medical complications
* pregnancy
* clinical cardiac arrhythmia