Clinical features of delusional beliefs in schizophrenic and unipolar mood disorders: a comparative study

We assessed comparatively 13 clinical features of delusions in a sample of 132 deluded inpatients of both sexes with schizophrenic (n = 89) or unipolar mood disorders (n = 43). Patients with schizophrenic disorders exhibited higher levels of severity than those with unipolar depression with respect to the features of vagueness-illogicality, bizarreness, systematization, conviction, duration and affective incongruence, whereas the reverse held true with respect to the feature of emotional impact. Furthermore, the two diagnostic groups were compared to each other with respect to patients' scores on five dimensions of their delusions obtained through factor analysis, namely emotional and behavioral impact, cognitive disintegration, delusional certainty, volitional dyscontrol and affective inappropriateness. Schizophrenic patients exhibited higher levels of severity than depressives on the second and fifth dimensions, whereas the reverse held true with respect to the fourth one. Our results suggest that particular features of delusions as well as broader dimensions thereof, may assist in the differential diagnosis of unipolar depression with psychotic features from schizophrenic disorders.