Scale for the Assessment of Negative Symptoms structure in first episode psychosis.

Previous studies in schizophrenia samples suggest negative symptoms can be categorized as expressivity or experiential. This study examines the structure of the Scale for the Assessment of Negative Symptoms (SANS) at two separate interviews in a first episode psychosis (FEP) sample. SANS structure was determined with principal components analysis in a schizophrenia spectrum (SSD, N=191) and non-schizophrenia spectrum (NSSD, N=246) sample at first presentation. Confirmatory factor analysis (CFA) was conducted in the entire FEP sample (N=197) at a follow-up assessment. A three factor model solution was extracted in both SSD and NSSD at first presentation. The three components, consisting of expressivity, experiential and alogia/inattention components, explained 26.1%, 16.6% and 13.6% of the variance respectively in SSD. In NSSD the same three components explained 24.2%, 17.9% and 13.1% of the variance respectively. CFA at follow-up showed similar model fit for both the original SANS five factor and for a three factor model solution. The results indicate that either a three or five factor SANS model solution may be appropriate in a psychosis sample inclusive of both SSD and NSSD. The findings also provide initial support for expressivity and experiential domain research in NSSD.