Validation of the Spanish version of the Clinical Assessment for Negative Symptoms (CAINS)
Negative symptoms are a core feature of schizophrenia and their reliable and valid assessment is a prerequisite for developing effective therapeutic interventions. This study examined the psychometric properties and validity of the Spanish version of a new rating instrument, the Clinical Assessment Interview for Negative Symptoms (CAINS). Outpatients and inpatients (N=100) with DSM-IV schizophrenia were administered the translated CAINS, the Positive and Negative Syndrome Scale (PANSS), the Scale for the Assessment of Negative Symptoms (SANS), and the Calgary Depression Scale for Schizophrenia (CDSS). A subsample (N=46) was rated for Parkinsonism using the Extrapyramidal Symptoms Rating Scale (ESRS). The scale showed good inter-rater and intra-rater reliability. Both the CAINS overall and the subscales for motivation/pleasure (CAINS-Map) and expression (CAINS-Exp) scores correlated significantly with the SANS and PANSS negative symptom scale. Significant correlations with positive symptoms and general psychopathology were also found, but these reduced and mostly became insignificant when overall severity of illness was controlled for. Significant correlations with depression also disappeared when severity was controlled for. There was a trend-level correlation between the CAINS total score and Parkinsonism, which reflected an association with the CAINS-Exp subscale only. Factor analysis revealed a two-dimensional structure that explained the 67.44% of the variance. Overall, the Spanish version of the CAINS appears to be a valid tool for measuring negative symptoms in schizophrenia.