A Two-Factor Model Better Explains Heterogeneity in Negative Symptoms: Evidence from the Positive and Negative Syndrome Scale.

Acknowledging separable factors underlying negative symptoms may lead to better understanding and treatment of negative symptoms in individuals with schizophrenia. The current study aimed to test whether the negative symptoms factor (NSF) of the Positive and Negative Syndrome Scale (PANSS) would be better represented by expressive and experiential deficit factors, rather than by a single factor model, using confirmatory factor analysis (CFA). Two hundred and twenty individuals with schizophrenia spectrum disorders completed the PANSS; subsamples additionally completed the Brief Negative Symptom Scale (BNSS) and the Motivation and Pleasure Scale-Self-Report (MAP-SR). CFA results indicated that the two-factor model fit the data better than the one-factor model; however, latent variables were closely correlated. The two-factor model's fit was significantly improved by accounting for correlated residuals between N2 (emotional withdrawal) and N6 (lack of spontaneity and flow of conversation), and between N4 (passive social withdrawal) and G16 (active social avoidance), possibly reflecting common method variance. The two NSF factors exhibited differential patterns of correlation with subdomains of the BNSS and MAP-SR. These results suggest that the PANSS NSF would be better represented by a two-factor model than by a single-factor one, and support the two-factor model's adequate criterion-related validity. Common method variance among several items may be a potential source of measurement error under a two-factor model of the PANSS NSF.

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.