Background. - The cross-sectional clinical differentiation of schizophrenia or schizoaffective disorder from mood-incongruent psychotic mania or mixed mania is difficult, since pathognomonic symptoms are lacking in these conditions.

Aims of the study. - To compare a series of clinical variables related to mood and cognition in patient groups with DSM-III-R diagnosis of schizophrenia, schizoaffective disorder, mood-incongruent psychotic mania and mood-incongruent psychotic mixed mania.

Methods. - One hundred and fifty-one consecutive patients were evaluated in the week prior to discharge by using the structured clinical interview for DSM-III-R-patient edition (SCID-P). Severity of psychopathology was assessed by the 18-item version of the brief psychiatric rating scale (BPRS) and negative symptoms by the scale for assessment of negative symptoms (SANS). Level of insight was assessed with the scale to assess unawareness of mental disorders (SUMD).

Results. - There were no differences in rates of specific types of delusions and hallucinations between subjects with schizophrenia, schizoaffective disorder, psychotic mania and psychotic mixed mania. SANS factors scores were significantly higher in patients with schizophrenia than in the bipolar groups. Patients with mixed state scored significantly higher on depression and excitement compared to schizophrenia group and, to a lesser extent, to schizoaffective group. Subjects with schizophrenia showed highest scores on the SUMD indicating that they were much more compromised on the insight dimension than subjects with psychotic mania or mixed mania.

Conclusion. - Negative rather than affective symptomatology may be a useful construct to differentiate between schizophrenia or schizoaffective disorders from mood-incongruent psychotic mania or mixed mania.