The Brief Negative Symptom Scale: Validation in a multicenter Brazilian study

BACKGROUND: Negative symptoms are a core feature of schizophrenia. The Brief Negative Symptom Scale (BNSS) is a scale developed to measure negative symptoms in schizophrenia. METHODS: The present study aimed to examine the construct validity of BNSS, by using convergent and divergent validities as well as factor analysis, in a Brazilian sample of 111 outpatients diagnosed with schizophrenia by DSM-5. Patients were evaluated by the Brazilian version of the BNSS and positive and negative subscales of the Positive and Negative Syndrome Scale (PANSS). RESULTS: Assessment of patients by both instruments revealed an excellent internal consistency (Cronbach's alpha = 0.938) or inter-rater reliability (ICC = 0.92), as well as a strong correlation between BNSS and Marder negative PANSS (r = 0.866) and a weak correlation of the instrument with the positive PANSS (r = 0.292), thus characterizing convergent and discriminant validities, respectively. The exploratory factor analysis identified two distinct factors, namely, motivation/pleasure and emotional expressivity, accounting for 68.63% of the total variance. CONCLUSION: The study shows that the Brazilian version of the BNSS has adequate psychometric properties and is a reliable instrument for the assessment of negative symptoms in schizophrenia, either for clinical practice or research.