Discrepancy of social cognition between bipolar disorders and major depressive disorders

Background: The research landscape examining social cognition (SC) impairment in patients with major depressive disorders (MDD) and bipolar disorders (BD) is notably scarce. Presently, assessments predominantly rely on static stimuli and self-reported measures, which may not capture the dynamic dimensions of social cognition. Objectives: This study aimed to validate the Chinese version of Movie Assessment of Social Cognition (MASC-CH) and to investigate whether MDD and BD exhibit distinct patterns of SC impairments, shedding light on potential differences between these two mood disorders. Methods: The study encompassed 197 participants, aged 18–65, distributed as follows: 21 BD, 20 MDD, and 156 healthy controls (HC). We focused on examining “cognitive” and “emotional” SC scores and “undermentalizing” and “overmentalizing” error patterns, with nonsocial inference as a control. Additional assessments included the Reading Mind in the Eyes Test (RMET) and the Mayer–Salovey–Caruso Emotional Intelligence Test (MSCEIT). We also explored the association between depression severity (measured by the Hamilton Depressive Rating Scale, HDRS) and distinct SC dimensions between MDD and BD. Results: The MASC-CH exhibited strong validity and reliability for SC assessment. In group comparisons, BD participants scored significantly lower on MASC-CH, while the MDD group scores were not significantly different from HC. Specifically, BD individuals had notably lower cognitive SC scores and made more undermentalizing and absence of mentalizing errors than MDD and HC. Additionally, a negative correlation between HDRS score and overmentalizing was observed in BD, not in the MDD. Conclusions: The findings indicate that depression severity scores in BD were inversely related to MASC-CH scores. In contrast, this relationship was not observed in the MDD group. These results underscore the importance of SC impairments as distinguishing characteristics of both BD and MDD. It provides valuable insights into the distinct social-cognitive profiles of both mood disorders.