Body representations in schizophrenia: an alteration of body structural description is common to people with schizophrenia while alterations of body image worsen with passivity symptoms.

Introduction: Individuals with schizophrenia, particularly those with passivity symptoms, often feel that their actions and thoughts are controlled by an external agent. Recent evidence has elucidated the role of body representations in the aetiology of passivity symptoms, yet one representation – body structural description – has not yet been examined. Additionally, body image has rarely been examined outside of bodily illusions (e.g., rubber hand experiments) and external validation is required.

Methods: Body structural description was assessed with an in-between task and a matching body parts by location task, and body image with a questionnaire examining body distortion experiences (containing subscales assessing boundary loss, depersonalisation and body size distortions). Individuals with schizophrenia (20 with current, 12 with past and 21 with no history of passivity symptoms) and 48 healthy controls participated in the study.

Results: People with schizophrenia (as a group) made more errors on the in-between task, but not on the matching body parts by location task. Individuals with current passivity symptoms reported greater distortions on all subscales relative to the other clinical samples, except for experiences of boundary loss which were common to both passivity symptom groups.

Conclusions: The results indicate that body structural description may be altered in schizophrenia generally and body image alterations are worsened in passivity symptoms, and these alterations likely contribute to the emergence of passivity symptoms