Theory of mind in Koreans with schizophrenia: A meta-analysis

Previous meta-analytic studies conducted in Western countries have consistently revealed impairments in theory of mind (ToM) in schizophrenia. However, there is no systematic meta-analytic review of ToM deficits in individuals with schizophrenia in non-Western countries. In addition, ToM impairments in individuals with schizophrenia have not been investigated in the distinctive domains (i.e., verbal vs. visual, or affective vs. cognitive). The current meta-analytic study systematically synthesized 13 studies comparing ToM performance of adults with schizophrenia (n=377) and that of healthy controls (n=386) in Korea. The results indicate that Koreans with schizophrenia showed overall large ToM impairments (d=-1.273) but intact performance in control tasks that require a similar amount of cognitive demand as ToM tasks do. Large impairments in affective and cognitive ToM (d=-1.445 and -1.202, respectively) and verbal and visual ToM (d=-1.239 and -1.221, respectively) were found in Koreans with schizophrenia. There were no differences in magnitude between affective and cognitive ToM or between verbal and visual ToM. These results suggest that Koreans with schizophrenia experience substantial impairments in various ToM domains. Comprehensive multi-modality-based assessment targeting various ToM domains should be considered for treatment planning of individuals with schizophrenia.