Factor structure of the Brief Psychiatric Rating Scale in unipolar depression

Abstract

Background: In clinical practice patients with unipolar depression present with a variety of symptom clusters that may combine together in many different ways. However, only few factor analytic studies used general psychopathology scales to investigate the symptom structure of unipolar depression. Methods: The study included 163 consecutive inpatients with an ICD-10 diagnosis of depressive disorder (ICD-10 codes F32 to F33). All patients were assessed with the 18-item version of the Brief Psychiatric Rating Scale (BPRS) within 3 days from admission. Exploratory factor analysis with Varimax rotation was performed on BPRS items. Results: Four factors were extracted, explaining 52% of total variance. They were interpreted as Apathy, Dysphoria, Depression and Psychoticism. The distribution of factor scores was approximately normal for Apathy, while it displayed a slight negative skewness for Depression, a slight positive skewness for Dysphoria, and a marked positive skewness for Psychoticism. Patient sex, family history of depression, lifetime history of suicide attempt, and recent serious family conflict were not associated with any factor. Occupational status, age, and age at onset displayed a positive correlation with Apathy. Duration of illness and number of previous admissions were positively correlated with Dysphoria. Limitations: Patients were not administered a structured diagnostic interview, and no detailed assessment of personality disorders was performed; also, patients were recruited only at a single site, which reduces the generalizability of the results. Conclusions: Our findings suggest that in depressive disorders there are psychopathological dimensions other than depressed mood that are worthy of greater clinical attention and research. Dimensions such as apathy and dysphoria may play an important part in the clinical phenomenology of unipolar depression and deserve systematic and careful assessment in order to provide patients with the best possible treatment and improve clinical outcomes.