Measuring negative symptoms in patients with schizophrenia: reliability and validity of the Korean version of the Motivation and Pleasure Scale-Self-Report

The Clinical Assessment Interview for Negative Symptoms (CAINS) is one of the validated interview measures of negative symptoms in psychotic disorders. The Motivation and Pleasure Scale-Self-Report (MPSR) is a self-report measure that assesses the motivation and pleasure domains of negative symptoms based on the CAINS. This study evaluated the reliability and validity of a Korean version of the MPSR. A total of 139 patients with schizophrenia completed the MPSR, CAINS, Scale for the Assessment of Negative Symptoms (SANS), Brief Psychiatric Rating Scales, Calgary Depression Scale for Schizophrenia, and other measures of trait and cognitive function. The 15-item MPSR showed good internal consistency. In addition, it also had a good convergent validity with the Motivation and Pleasure subscale of the CAINS and the anhedonia/avolition subscale of the SANS. The scale was not associated with psychotic symptoms, agitation/mania, and depression/anxiety, and it showed good discriminant validity. MPSR scores were significantly correlated with Behavioral Activation System total score for trait measure. The Korean version of the MPSR is a notable self-report method for examining the severity of negative symptoms in schizophrenia.