Background: Impaired social cognition (SC) occurs frequently in schizophrenia (SCZ), yet compared to autism spectrum disorder (ASD), the research on SC in SCZ is sparse and methodologically heterogeneous. To accurately assess between-group SC differences it is further necessary to establish the relationship between nonsocial cognition (NSC) and SC, particularly as this may not be identical across disorders.
Purpose: The present study aimed to map, index and assess the quality of research published between 2014-2021 investigating SC in SCZ, and to summarize existing limitations and recommendations for future research.
Method: Following the PRISMA guidelines for scoping reviews (PRISMA-ScR) fifteen (n = 15) case-control studies were identified and included across three electronic databases. Studies additionally utilizing ASD samples were included because of their clinical utility.
Results: Most studies reported significant SC impairments in SCZ relative to healthy controls (HC) with varying effect sizes. Significant differences between SCZ and ASD were not found in most studies including both samples. Weak-to-moderate correlations between SC and NSC were often found, although often only within patient samples. Across studies, SC tests were inconsistently described as measurements of "social cognition", "mentalization" and, most frequently and varyingly, "theory of mind". Most studies lacked methodological transparency. Limitations related to sample sizes and test reliability were most frequently mentioned.
Conclusions: The current research on SC in SCZ is limited by conceptual and methodological uncertainties. Future research should focus on ensuring clear and valid definitions of key terms, evaluating and clarifying SC outcome measures and further untangling the relationship between SC and NSC.
Keywords: Social cognition; autism spectrum disorder (ASD); mentalization; schizophrenia (SCZ); scoping review; theory of mind (ToM).