The influence of social cognition on ego disturbances in patients with schizophrenia.

BACKGROUND Subjects experiencing ego disturbances can be classified as a distinct subgroup of schizophrenia patients. These symptoms imply a disturbance in the ego-world boundary, which in turn implies aberrations in the perception, processing and understanding of social information. This paper provides a comparison of a group of schizophrenia patients and a group of healthy controls on a range of social-cognitive tasks. Furthermore, it analyzes the relationship between ego disturbances and social-cognitive as well as clinical variables in the schizophrenia subsample. METHODS Two groups - 40 schizophrenia patients and 39 healthy subjects - were compared. In the source monitoring task, subjects performed simple computer mouse movements and evaluated the partially manipulated visual feedback as either self- or other-generated. In a second step, participants indicated the confidence of their decision on a 4-point rating scale. In an emotion-recognition task, subjects had to identify 6 basic emotions in the prosody of spoken sentences. In the 'reading-the-mind-in-the-eyes' test, subjects had to infer mental states from pictures that depicted others' eyes. In an attribution task, subjects were presented with descriptions of social events and asked to attribute the cause of the event either to a person, an object or a situation. Additionally, all subjects were tested for cognitive functioning levels. RESULTS The schizophrenia patient group performed significantly worse on all social-cognitive tasks than the healthy control group. Correlation analysis showed that ego disturbances were related to deficits in person attribution and lower levels of confidence in the source monitoring task. Also, ego disturbances were related to higher PANSS positive scores and a higher number of hospitalizations. Stepwise regression analysis revealed that social-cognitive variables explained 48.0% of the variance in the ego-disturbance score and represented the best predictors for ego disturbances. One particular clinical variable, namely the number of hospitalizations, additionally explained 13.8% of the variance. CONCLUSION Our findings suggest that ego disturbances are related to deficits in the social-cognitive domain, and, to a lesser extent, to clinical variables such as the number of hospitalizations.