Study of the concurrent validity of the Calgary Depression Scale for Schizophrenics (CDSS)

The aim of this study was to investigate the concurrent validity of the French language version of the Calgary Depression Scale for Schizophrenics (CDSS). Ninety-five schizophrenic patients meeting the DSM-III-R criteria were enrolled in the study. The depressive symptoms were evaluated using the Calgary Depression Scale for Schizophrenics (CDSS), Hamilton Depression Rating Scale (HDRS), Montgomery and Asberg Rating Scale (MADRS), and Widlocher Psychomotor Retardation Scale (ERD). The psychotic symptoms were evaluated with the Positive and Negative Syndrome Scale (PANSS) and the extrapyramidal symptoms with the Extrapyramidal Syndrome Rating Scale (ESRS). The CDDS was significantly correlated with all the conventional depression-rating scales. We only found significant positive correlations between the CDSS and the PANSS-positive sub-scale. The CDSS total score was significantly correlated with some PANSS-positive items (delusions and hallucinatory behaviour). No significant correlation between the depression-rating scales and the PANSS-negative sub-scale was observed. For all the depression-rating scales, no correlation with the extrapyramidal symptom was evidenced. The results confirmed the validity of the CDSS in the evaluation of depression in schizophrenia. The relationship between depression and the positive symptoms of schizophrenia is discussed.