Background: A consistent amount of empirical research suggests that depression, besides interfering with quality of life and social functioning, may influence other symptom dimensions in schizophrenia, thus constituting an important domain for treatment strategies, outcome, and prognosis.
Aim: This study investigated the factorial structure of the Calgary depression scale for schizophrenia (CDSS) in a sample of schizophrenic patients and explored the relationships between such factors, major symptom dimensions and subjective experiences.
Methods: One hundred and sixty-one subjects were examined to assess the severity of schizophrenic symptoms (scored according to the five-dimensional model of Toomey et al. [28]), the distress due to the subjective experience of negative symptoms, and the degree of subjectively-felt cognitive-affective vulnerability (i.e. basic symptoms).
Results: Principal component analysis revealed CDSS to include three main factors, namely: "depression-hopelessness" (factor I), "guilty idea of reference-pathological guilt" (factor II) and "early wakening" (factor III). Whereas the last factor did not correlate with any of the other psychopathological domains, the first two factors revealed multiple correlations with both diagnostic symptoms and subjective experiences.
Conclusions: The results confirm the threefold factorial structure of the CDSS previously reported by the authors of the scale and could shed further light on the psychopathological nature of the components of depression in schizophrenia. The specific correlation patterns with diagnostic and subjective psychopatholgy substantiate the clinical distinction between a general depression factor ("depression-hopelessness") and a cognitive-guilt factor ("guilty idea of reference-pathological guilt").