Exogenous Modulation of Visual Perception And Connectivity in Body Dysmorphic Disorder (EMPAC-BDD) - PROJECT SUMMARY Individuals with body dysmorphic disorder (BDD) misperceive 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. Previous research has uncovered mechanisms that may contribute to perceptual distortions, including prominent abnormalities in visual processing systems. These have contributed to a model of diminished global/holistic processing and enhanced local/detailed processing, attributed to “bottom-up” and “top-down” disturbances in perception. Previous experiments using psychophysical tests, novel behavioral visual modulation techniques, and functional magnetic resonance imaging (fMRI) have probed the brain’s visual systems responsible for global and local processing and found early evidence that they may be modifiable in BDD. This study will test if further modification could be achieved using noninvasive neuromodulation with repetitive transcranial magnetic stimulation (TMS). Such modulation may be necessary to enhance the effects of behavioral modulation and induce the magnitude of functional changes necessary to achieve clinically meaningful improvements in perceptual experiences in those with BDD. The proposed experiment will determine whether excitatory and inhibitory TMS enhances and inhibits, respectively, the effects of a behavioral visual modulation strategy on brain connectivity and on global visual processing on a psychophysical task. This will be tested in individuals with clinical BDD and in individuals with subclinical BDD. Results will contribute to a comprehensive mechanistic model of abnormal visual information processing underlying the core symptom domain of misperceptions of appearance. Further, results will be critical for the development and optimization of future combinations of neuromodulation and novel perceptual retraining treatments.
