Subjective Scale to Investigate Cognition in Schizophrenia (SSTICS): a validation study in Italian population

Background. Although cognitive deficit in persons with schizophrenia is well documented, the assessment of the patient's perception of its own cognitive functioning is a relevant issue not adequately studied. Several evaluation tools have been elaborated, however none has been validated in Italian. The aim of the study is the validation of the Subjective Scale to Investigate Cognition in Schizophrenia (SSTICS), a rating scale designed to measure subjective cognitive deficits complaints in persons with schizophrenia. Method. 146 persons meeting the DSM-5 diagnostic criteria for schizophrenia have been recruited. The SSTICS was translated in Italian in accordance with international standard methods. Subjects were also evaluated using the Positive and Negative Syndrome Scale (PANSS) and the Subjective Well-being under Neuroleptic scale (SWN). Cronbach's alpha coefficient was used to assess internal consistency. Constructs were examined using exploratory factor analysis (principal component with varimax rotation). The factorial model was then tested via confirmatory factor analysis. Results. The factorial analysis revealed a 4-factor structure, which is more parsimonious than those obtained in previous studies. Correlations between STICSS and the other rating scales were significant for several domains. Conclusions. The Italian version of the SSTICS showed good psychometric properties and is suitable to measure the patients' subjective perception of cognitive impairment. Subjective evaluation can integrate objective measures of cognitive performances, supporting a multidimensional model of functional impairment in schizophrenia.