Background: Current research suggests that negative symptoms may not be a unitary construct. Factor analytic studies typically found evidence for a two-factor solution of the negative symptom domain: the expressive and the volitional deficit. This study aimed to investigate whether the two-factor solution of negative symptoms is supported across different evaluation instruments: PANSS and NSA-16 in outpatients with schizophrenia and to explore the relationship between these domains and sociodemographic, clinical, and metabolic outcomes routinely assessed in daily practice. Another aim was to determine clinical predictors of negative symptoms domains among these variables.
Materials and methods: 107 patients with schizophrenia were included in this cross-sectional study. The Principal Component Analysis was used to identify negative symptom domains, and Spearman's rank correlation coefficient and multiple regression analyses were used to assess the relationship between the negative symptoms domains and clinical variables.
Results: PCA indicated a two-component solution explaining 85.2% of the variance for the NSA-16 subscales, reflecting an expressive deficit and an experiential deficit component. The age of onset of the disease and the cognitive deficit were significant predictors of the expressive deficit, body mass index, and the number of admissions in the hospital for the experiential deficit.
Conclusions: The current findings indicate that the expressive deficit and the experiential deficit should be considered distinct domains of psychopathology and should be rated separately.
Key words: expressive deficit, experiential deficit, negative symptoms, predictive factors, schizophrenia
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