Delusional disorder has been traditionally thought to be a disorder that does not evolve to defective states. However, little empirical evidence has been obtained so far comparing these patients with other psychotic conditions. Our aim is to characterize delusional disorder patients as compared to other psychotic patients regarding to their psychopathology, neuropsychological performance and general functioning.

A total of 131 psychotic patients were included in this study. 22 patients with delusional disorder, 109 other psychosis. Psychopathology was assessed via PANSS. DKEFS Colour-Word Stroop test was used to assess neuropsychological performance. Functioning was assessed using GAF. Between groups comparisons were performed via ANOVA and post hoc tests using Bonferroni method were subsequently used. Using the inclusive criterion, PANSS's positive and negative subtypes distribution was investigated in the groups using χ2 tests.

Statistically significant differences between patients with schizophrenia and patients with delusional disorder were found for PANSS's negative scale, the scoring was significantly lower for emotional withdrawal, blunted affect, difficulty in abstract thinking and stereotype thinking. There were no statistically significant difference between the groups regarding the rest of scales of PANSS (positive and general psychopathology), neuropsychological performance and functioning.

Even though delusional disorder is considered as a clinical entity more benign than other psychoses, our data show that these patients are only less seriously affected regarding negative symptomatology. In line with the recent nosological progress, these results would support a dimensional conceptualization of psychosis.