Guilt and depression: two different factors in individuals with negative symptoms of schizophrenia

Depression is common among schizophrenia patients and constitutes a major risk factor for suicide. Calgary Depression Scale (CDSS) is the most widely used instrument for measuring depression in schizophrenia. CDSS has never been examined in patients with predominant negative symptoms, thus possibly hindering both accurate assessment and understanding of the underlying mechanisms. The current study is the first to examine CDSS' structure in this population.

We conducted Principal Component Analysis (n=184) for the CDSS items. Thereafter, we correlated emerging factors with psychopathological, demographic and side effect variables. We assessed internal consistency and reliability of the emerging factors, as well as demographic correlations.

The analysis yielded two factors: depression-hopelessness and guilt. Factors distinctly correlated with separate variables. Removal of item #7 (early waking) improved internal consistency. The depression-hopelessness factor had an inverse correlation with negative symptoms, and positive correlation with neuroleptic side effects.

CDSS structure indicated of two separate factors, i.e., depression-hopelessness and guilt, suggesting separate underlying processes. The validity of the scale might benefit from a two-fold structure and the removal/replacement of item #7 (early waking). A noteworthy inverse correlation was found between the depression factor and negative symptoms, as well as a positive correlation between depression factor and neuroleptic side effects.