No abstract

Introduction: Psychotic depression (PD) is classified as a sybtype of severe depression in the current diagnostic manuals. Accordingly, it is a common conception that psychotic features in depression arise as a consequence of depressive severity. Objectives: To determine whether the severity of depression and psychosis correlate in accordance with the "severity-psychosis" hypothesis and to detect potential differences in clinical features of psychotic and non-psychotic depression (non-PD). Aims: We aimed to answer the following questions: • Does the clinical profile differ between patients with PD and non-PD? • Is the severity of depression and psychosis correlated in patients with depression? Methods: Quantitative analysis of Health of the Nation Outcome Scales (HoNOS) scores from all patients admitted to a Danish general psychiatric hospital between 2000 and 2010 due to a severe depressive episode. Results: A total of 357 patients with severe depression, of which 125 (35%) were of the psychotic subtype, formed the study sample. Mean HoNOS scores at admission differed significantly between patients with non-PD and PD on the items hallucinations and delusions (non-PD=0.33 vs. PD=1.37, p< 0.001), aggression (non-PD=0.20 vs. PD=0.36, p=0.044) and on the total score (non-PD=10.55 vs. PD=11.87, p=0.024). The HoNOS scores on the two items "depression" and " hallucinations and delusions" were very weakly correlated (Spearman coefficient=0.12). Conclusions: The results suggest that the severity of depression is unlikely to be the key determinant for the development of psychosis and supports the hypothesis that the psychotic-and non-psychotic subtypes of depression are in fact distinct clinical syndromes.