Introduction: Personality disorders (PD) and schizophrenia spectrum disorders (SSD) are distinct conditions displaying common symptoms, like impairments in social cognition, that make them hard to distinguish, especially in severe cases. To date, few studies have compared theory of mind skills in these two disorders, and none have compared social knowledge skills. This study aims to compare the social cognitive abilities of patients with these conditions.
Method: Non-parametric analyses of covariance were used to compare severe PD patients (n = 37), SSD patients (n = 44), and healthy controls (HC; n = 49) on the Social Knowledge Test and two measures of theory of mind: the Reading the Mind in the Eyes Test and the Combined Stories Test, which incorporates items from various widely used tests.
Results: While no significant group differences were found on the Social Knowledge Test, SSD patients performed lower than the HC group on both theory of mind tests. PD patients only had lower performance than the HC group on specific items from the Combined Stories Test.
Conclusions: PD and SSD patients demonstrated distinctive patterns of social cognitive impairments, with items of greater complexity or with an affective orientation being the most discriminant for PD.
Keywords: Social cognition; personality disorders; schizophrenia spectrum disorders; social knowledge; theory of mind.