[Sense of body in schizophrenia]

First-rank symptoms of schizophrenia have been related to an impaired sense of agency (the sense of causing and controlling an action). The sense of agency is considered as one of the two components of self-recognition, the other component being the sense of body (awareness of one's body). The present study aimed at evaluating whether first-rank symptoms can be considered as a general impairment in self-recognition that will also concern the sense of body. A group of schizophrenic patients with first-rank symptoms, a group of schizophrenic patients without first-rank symptoms and a group of normal subjects were compared in a self-recognition task where they first had to execute hand movements simultaneously with the experimenter and subsequently to indicate the position either of their own or the experimenter's hand. The visualized locations of the hands could rotate by 0 degrees , 90 degrees , -90 degrees or 180 degrees from their real locations. This rotation allowed us to induce a distorted sense of body since there was a visual discontinuity between the patient's hand and the rest of his/her body. If patients present a perturbed sense of body we would expect a greater impairment in discriminating between their own hand and the experimenter's hand as the rotation values increased. This preliminary study shows that patients with first-rank symptoms are more impaired than normal subjects in distinguishing between their own hands and the experimenter's hands when the visualization of the locations of their hands were rotated respective to their real locations. However, both group of patients performed equally, thus showing that sense of body impairment is not specific to first-rank symptoms. These symptoms, compared to other symptoms of schizophrenia do not reflect general self-recognition impairment but rather a specific impairment of the sense of agency.