Depression in schizophrenia: a comparison of three measures

Depression, as a feature of schizophrenia, is well established. However, clarifying the exact nature of this relationship has been problematic. The clinical measures routinely utilized to evaluate depression have not been specifically designed for use in schizophrenia, and it is well recognized that a variety of depressive symptoms overlap with other features common to this illness, e.g. negative symptoms, neuroleptic induced side effects. The present study compared three commonly used measures of depression (Hamilton Depression Rating Scale (Ham-D), Calgary Depression Scale (CDS) and the depression subscale of the Positive and Negative Syndrome scale (PANSS-D) in a group of outpatients with schizophrenia, evaluating the degree of association between the scales. Additionally, the relationship between each of the depression measures, negative symptoms and extrapyramidal symptoms (EPS) was calculated. Results revealed that all three measures of depression were significantly correlated, although the CDS was unique in its ability to distinguish between depression, negative symptoms and EPS. It is concluded that the CDS, when compared with the HAM-D and the PANSS-D, is the most suitable measure of depression in schizophrenia.