Different aspects of theory of mind in paranoid schizophrenia: evidence from a video-based assessment

In schizophrenia, impairments of theory of mind (ToM) may be due to excessive ('overmentalizing') or defective ('undermentalizing') attribution of mental states. However, most ToM tests differentiate neither between 'overmentalizing' and 'undermentalizing' nor between cognitive and affective ToM in schizophrenia. This study aimed at differentiating these aspects of ToM in 80 patients diagnosed with paranoid schizophrenia and 80 matched healthy controls using the 'Movie for the Assessment of Social Cognition' (MASC). Outcome parameters comprised 1) error counts representing 'undermentalizing' or 'overmentalizing', 2) decoding of cognitive or emotional mental states and 3) non-social inferencing. Multivariate analysis of covariance (MANCOVA) showed significantly abnormal scores for two dimensions of 'undermentalizing' as well as for cognitive and emotional ToM that were not explained by global cognitive deficits. Scores for 'overmentalizing' did not differ between groups, when age, gender, non-social reasoning and memory were controlled. In schizophrenic patients, negative symptoms were associated with a lack of a mental state concept, while positive symptoms like delusions were associated with 'overmentalizing', supporting respective etiological concepts of delusions.