M110. Capturing Self Disturbances in Individuals With Schizophrenia; Introducing the BODI

Abstract

Background: Anomalous or weakened sense of self was central to early theories of schizophrenia. Recent empirical studies have also documented disturbances in body ownership and increased susceptibility for dissociative experiences, such as the out-of-body experience in patients with schizo-phrenia. We argue that predictive coding is not possible if egocentric and allocentric representations of the body do not coincide with the perceived self-location. To assess the extent of unusual bodily experiences and associ-ated distress in persons with schizophrenia, individuals at risk for psychosis and healthy controls, we developed a new picture-based measure, the BODI (Brugger et al. Out-of-body and Dissociative Experiences Inventory). Method(s): Patients with schizophrenia, prodromal individuals and demo-graphically matched healthy participants participated in this study. BODI consisted of line drawings that depict unusual bodily experiences (eg, autoscopy, feeling of presence, etc.) and common ones (eg, itching, tickling, etc). The drawings were adapted from those used to assess autoscopic or heautoscopic experiences in patients with brain lesions. After viewing each picture, participants were asked whether they have experienced it, and if so, provide frequency, similarity and distress ratings. BODI was tested in relation to established self-report questionnaires of psychosis-proneness (Perceptual Aberration Scale), dissociative experiences (DES-II) and loneliness (UCLA loneliness scale). Furthermore, we examined neuropsychologi-cal and proprioceptive correlates of the BODI. Result(s): The BODI accurately captured bodily self-aberrations in both patients with schizophrenia and healthy controls. Furthermore it distinguished prodromal individuals at risk for psychosis from healthy controls. BODI was associated with increased positive symptoms in patients, and elevated schizotypy in healthy participants. Overall, BODI score was correlated with behavioral signs of temporoparietal abnormalities and increased susceptibility to tactile-proprioceptive illusions. Lastly, social isolation appeared to exacerbate the BODI score across the schizophrenia-spectrum. Conclusion(s): These fndings provide evidence for the hypothesis that weakened sense of body and related self-aberrations may be central to the prodromal stage of schizophrenia, and dissociative experiences may be a latent risk factor for psychosis.