Neural mechanisms of perceptual abnormalities and their malleability in bodydysmorphic disorder

Centre For Addiction And Mental Health, Toronto ON

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Abstract

Abstract Individuals with body dysmorphic disorder (BDD) misperceive specific aspects of their appearance to be conspicuously flawed or defective, despite these being unnoticeable or appearing miniscule to others. With convictions of disfigurement and ugliness, they typically have poor insight or delusional beliefs, obsessive thoughts and compulsive behaviors, anxiety, and depression. These result in significant difficulties in functioning, depression, suicide attempts (25%), and psychiatric hospitalization (50%). Despite this, relatively few studies of the neurobiology, and few treatment studies, have been conducted. This underscores a critical need for research to identify novel targets for intervention based on a comprehensive understanding of the pathophysiological mechanisms. While preoccupation with misperceived appearance features of the face and head are common in BDD, additional concerns about the body (from the neck down) are also highly prevalent. Yet, misperceptions of the body are often of a different nature than face concerns; these typically pertain to the size and shape of body parts rather than specific details. Common examples are that one’s thighs are too large or small, or that one’s chest is too large or small. Face concerns, on the other hand, typically involve misperception of small details, e.g. skin blemishes. Size/shape misperceptions may have different causes related to brain functioning and behaviors than those involving details. Further, distortions of one’s internal self- body image (one’s imagined body in the absence of a stimuli such as a mirror) may contribute to appearance preoccupations. We plan to uncover mechanisms of body misperception in the context of self-body representations by determining own-body size estimation accuracy while also measuring brain function and eye behaviors. The additional experimental procedures will use a digital avatar tool, Somatomap 3D, to quantify body size estimation, while simultaneously obtaining fMRI and eye-tracking data. With data collected in the overall study, the results promise to provide valuable information to help develop new targeted behavioral, perceptual, and/or brain stimulation treatments to address body image distortion that involve appearance aspects of the body or face.