Prevalence of depression and its relationship with other clinical characteristics in a sample of patients with stable schizophrenia

Aim: To evaluate the prevalence of depression using the Calgary Depression Scale for Schizophrenia (CDSS) in a sample of Spanish patients with stable schizophrenia and without a diagnosis of depression.

Methods: We included stable outpatients of 18 to 50 years of age, with a diagnosis of schizophrenia, schizoaffective disorder, or schizophreniform disorder who had not been diagnosed with depression. In this cross-sectional study, we administered the CDSS, the Positive and Negative Syndrome Scale (PANSS), the Scale for the Assessment of Negative Symptoms (SANS), the Scale to Assess Unawareness of Mental Disorder (SUMD), the Simpson Angus Scale (SAS), and the Barnes Akathisia Rating Scale (BARS).

Results: A total of 95 patients were recruited, 90 of them were included in the statistical analysis. Twenty-eight patients had a total score of 5 or more points on the CDSS, making the prevalence of depression 31% (95% confidence interval, 22-41). The CDSS had a high correlation with the depressive factor of the PANSS and a moderate correlation with the general psychopathology subscale of the PANSS. The correlation of the CDSS total score with negative symptoms was moderate using the SANS and low with the PANSS-negative. There was no correlation between depressive symptoms and positive symptoms, insight, and extrapyramidal symptoms; and the correlation with akathisia was low.

Conclusion: Our results suggest that patients with stable schizophrenia who have not been diagnosed with depression frequently have clinically relevant symptoms of depression, and that these symptoms, with the possible exception of a contribution from negative symptoms, are not secondary to other symptoms of their disorder or to extrapyramidal adverse effects of medications.