Nearly one-third of adults with stable schizophrenia also met independent clinical criteria for depression, findings from an analysis of 90 patients have shown.
Overall, 28 of the 90 patients (31%) had scores of 5 or more on the Calgary Depression Scale for Schizophrenia (CDSS), which is highly correlated with other measures of depression, said Dr. Susana Majadas of the Universidad de Salamanca (Spain) and her colleagues.
Data from previous studies have shown depressive symptoms in many patients with schizophrenia, but some clinicians maintain that these symptoms are secondary to schizophrenia or a side effect of treatment, the researchers noted.
In this study, the researchers analyzed 90 stable schizophrenia outpatients aged 18-50 years across five centers in Spain; 75 had a diagnosis of schizophrenia and 15 had a schizoaffective disorder. The mean age of the patients was 35 years, and 59% were men (Comp. Psychiatry 2012;53:145-51).
The prevalence of depression was 33% in patients with schizophrenia and 20% in those with a schizoaffective disorder. The prevalence of depression was not significantly different in men vs. women (34% vs. 27%).
The patients’ treatments included risperidone (32 patients), quetiapine (21 patients), olanzapine (9 patients), fluphenazine (6 patients), amisulpride (6 patients), and other antipsychotics (14 patients).
When the presence of depression was analyzed according to antipsychotic treatment, the criteria for depression (a CDSS score below 5) were not met in 90% of patients on quetiapine, 67% of patients on fluphenazine, 56% of those on risperidone, and 44% of those on olanzapine, the researchers noted.
"Depression appears to be associated with a greater severity of disease, and in part, overlaps with negative symptoms," the researchers said.
The study is the first to use the CDSS to assess depression in schizophrenia patients, and the prevalence rates are similar to those found in other studies, they noted. Although the study was limited by its cross-sectional design, which did not permit the evaluation of symptoms over time, the findings suggest that clinical depression is often present in stable schizophrenia patients. The findings also suggest that depressive symptoms are not secondary to schizophrenia symptoms or the effects of medication, Dr. Majadas and her colleagues added.
The researchers said they had no relevant financial disclosures.