Anorexia Nervosa (AN) is considered one of the most severe subtypes of eating disorders (EDs), characterized by significant medical complications, high mortality rates, and high comorbidity with other disorders, such as anxiety disorders. Similarly to what occurs in anxiety disorders, several studies have suggested the presence of dysfunctional body-related attentional bias (AB) in patients with EDs, and specifically in patients with AN. Individuals with AN tend to focus their attention on their body in a dysfunctional manner, engaging in body-checking behaviors and excessively scrutinizing their general appearance and weight-related body parts. This body-related AB has been associated with higher levels of body dissatisfaction, which represents one of the most important risk factors for the development and maintenance of EDs.

Moreover, body-related AB may contribute to reducing the effectiveness of body exposure-based treatments used in patients with AN. For this reason, it is necessary to develop new treatment techniques by incorporating specific components aimed at reducing body-related AB. It has been proposed that attentional bias modification techniques could be integrated into body exposure therapy as an effective approach to reduce body-related AB, body dissatisfaction, and body anxiety.

To date, our research group has been the first to use a combination of virtual reality (VR) and eye-tracking (ET) technologies to assess the presence of body-related AB in non-clinical samples. In order to improve treatments for AN, the present project aims to develop a novel attentional bias modification procedure using ET and VR technologies. In addition, this project seeks to integrate this AB modification procedure into a body exposure-based treatment designed to reduce the fear of weight gain experienced by patients with AN.

Finally, the project aims to evaluate whether combining two distinct components-body exposure-based therapy and attentional bias modification training-results in a more effective intervention. It is expected that the inclusion of a VR-based body exposure procedure in standard AN treatment, enhanced through the illusion of ownership over a virtual body, will lead to improved treatment outcomes. Furthermore, it is anticipated that the addition of attentional bias modification training to the body exposure-based procedure will further enhance treatment effectiveness.

Attentional bias (AB) refers to the tendency to allocate greater attention to certain types of stimuli or information (e.g., disorder-relevant information) over other types of information. Adolescent patients with Anorexia Nervosa (AN) have been shown to focus more on self-perceived unattractive body parts than on other body parts. Dysfunctional body-related AB is thought to maintain body image disturbances commonly reported by adolescents with AN by selectively processing body-related information that is consistent with dysfunctional cognitive schemas (e.g., "I am getting a fatter belly"), while schema-inconsistent information (e.g., "I am getting thinner") receives less attention and is often visually neglected.

Dysfunctional body-related AB may also contribute to the reduced effectiveness of body exposure-based treatments for adolescents with AN. Therefore, there is a need to develop novel treatment approaches by incorporating specific components aimed at reducing body-related AB in this population. In a previous project conducted by our group, preliminary evidence supported the effectiveness of body-related AB modification in adolescent patients with AN following a virtual reality (VR)-based mirror exposure intervention. A key factor underlying these results may lie in the structure of the procedure, in which patients were required to sequentially focus on different parts of a virtual body (from head to feet) and verbally express their thoughts and emotions related to each body area.

Building on these findings, the present project aims to further advance this line of research by integrating attentional bias modification techniques into body exposure therapy as an effective approach to reducing body-related AB, body dissatisfaction, and body anxiety in adolescents with AN. To date, our research group has been among the first to combine virtual reality (VR) and eye-tracking (ET) technologies to assess body-related AB in both clinical and non-clinical samples. Specifically, this project seeks to determine whether the addition of attentional bias modification training to body exposure-based therapy results in a more effective intervention for adolescents diagnosed with AN.

It is hypothesized that incorporating AB modification training into the body exposure-based procedure (experimental group) will lead to greater treatment efficacy compared with treatment as usual (control group). Specifically, adolescents in the experimental group are expected to show a significant increase in body mass index (BMI) and a significant reduction in core AN symptomatology (e.g., fear of weight gain, body image disturbances), as well as a reduction in body-related AB, from pre- to post-treatment, compared with the control group. These improvements are also expected to be maintained at the six-month follow-up.

The project will be conducted at the Eating Disorders Units of Hospital Sant Joan de Déu (Barcelona, Spain), which specializes in the treatment of adolescents with eating disorders.

Adolescent patients with AN will be exposed to an immersive virtual environment using a VR head-mounted display (HTC Pro Eye) equipped with integrated eye-tracking. In addition to the two controllers typically provided with the HTC Pro Eye system, three additional body trackers will be used to enable full-body motion tracking. The virtual environment will consist of a room featuring a large mirror positioned on the front wall, approximately 1.5 m in front of the participant, and large enough to reflect the entire body. A young female avatar wearing a basic white T-shirt, blue jeans, and black trainers will be created for the intervention.

Regarding the treatment protocol, all sessions will last approximately one hour and will be conducted once per week. Each session will begin with the induction of the full-body illusion (FBI) and the assessment of visual analogue scales (VASs). Body exposure will initially involve a virtual body with the same BMI as the adolescent patient. The attentional bias modification training will be based on an adaptation of the AB induction procedure proposed by Smeets, Jansen, and Roefs (2011). The training will involve the visual selection of geometric figures (e.g., squares, rectangles, circles) that approximately correspond to specific body parts, with each figure presented in different colors. Participants will be required to detect and identify figures appearing on different parts of the avatar's body. In 50% of the trials, discrimination will be based on shape, while in the remaining 50% it will be based on color. Throughout the training, figures will appear on weight-related body parts in 45% of the trials and on non-weight-related body parts in another 45% of the trials. In the remaining 10% of trials, figures will appear on one of three neutral stimuli positioned next to the avatar.

Raw eye-tracking data will be processed using Ogama (Open Gaze and Mouse Analyzer) software to obtain quantitative measures of visual attention. Weight-related and non-weight-related areas of interest (AOIs) will be defined a priori. Weight-related AOIs will be determined based on the weight-related body items of the PASTAS questionnaire and mapped onto a frontal-view image of a female avatar. These weight-related AOIs will include the legs, thighs, buttocks, hips, abdomen, and waist. All remaining body parts (head, neck, chest, shoulders, arms, and feet) will be classified as non-weight-related AOIs. Selective visual attention will be assessed using total fixation duration and the number of fixations within each AOI.

Inclusion Criteria:

• Female adolescents aged 12-17 years.
• Primary diagnosis of anorexia nervosa according to DSM-5 criteria.
• Body weight below the expected range for height, age, and sex.
• Ability to understand and communicate in Spanish.

Exclusion Criteria:

• Presence of severe mental disorders other than anorexia nervosa.
• Significant cognitive impairment that would interfere with participation.
• Visual or auditory deficits that could interfere with VR-based body exposure therapy.
• Epilepsy.
• Pregnancy.
• Cardiac arrhythmia.

The data presented in this study will be available on request from the corresponding author. The data are not publicly available due to patients' privacy restrictions.