A validation for the Subjective Cognitive Impairment Scale (SCIS) in patients with first-episode Schizophrenia Spectrum Disorder

Abstract

OBJECTIVES:. Cognitive deficit is a core feature of schizophrenia. Recently, subjective cognitive impairment has received increasing attention. Such impairment reflects the self-perceived cognitive difficulties of patients in their daily activities and was found to predate onset and relapse of schizophrenia. However, this construct is under-studied. This study aimed to validate the Subjective Cognitive Impairment Scale (SCIS), which was designed specifically for schizophrenia patients. The scale was developed using a bottom-up approach; 30 first-episode schizophrenic patients were asked to describe their daily cognitive difficulties. Items underwent systematic review and refinement. METHODS: The 31-item scale was administered to 101 patients with first-episode schizophrenia spectrum disorder. Construct validity of SCIS were examined by principal component factor analysis, while the reliability of SCIS was evaluated using its internal consistency. The relationships of SCIS with sociodemographics and clinical characteristics were investigated using Spearman rank correlation. RESULTS: Factor analysis revealed 9 factors with an eigenvalue larger than 1. Based on further analysis, only factor 1 was retained. Factor 1 accounted for 32.26% of the variance. Cronbach’s alpha coefficient for the 30-item scale was 0.92 after removing item 1. There were significant correlations between each item and the total score (p < 0.01). Greater SCIS score was associated with higher score on Positive and Negative Syndrome Scale (PANSS) cognitive factor (Spearman rho = 0.29, p < 0.01) and depression and anxiety factor (Spearman rho = 0.41, p < 0.001), and prolonged duration of untreated psychosis (Spearman rho = 0.24, p < 0.05). CONCLUSIONS: The current study provided preliminary support for the reliability and validity of SCIS. Future studies could employ SCIS in examining the relationship between subjective and objective cognitive impairments.