Differential Diagnosis
The differential diagnosis of schizoaffective disorder is not easy as it combines symptoms of several disorders. In psychotic depressive, manic or mixed episodes, hallucina- tions that might exist are congruent to the modified mood of the patients (synthymic). Yet, after especially DSM-IV had accepted even mood-incongruent symptoms in psychotic de- pression, mania or mixed states, differential diagnosis has become even more difficult. It has to be made according to the criteria described at the beginning of this paper. Psy- chotic depression, mania or mixed states with mood-incon- gruent psychotic symptoms, however, should better be allo- cated to schizoaffective disorders.51)
Depressive symptoms are not rare in schizophrenia. The depressive symptomatology, however, does not meet the cri- teria of major depression. So-called “postschizophrenic de- pression” or “postremissive fatigue syndrome” can be dif- ferentiated from schizoaffective episodes by their occurrence after the schizophrenic episodes have remitted and by the fact that they do not meet the criteria of major de- pression. Maniform symptomatology in schizophrenia can be characterized by hyperactivity or euphoria but does not meet the criteria of a manic episode. “Cycloid psychosis”, or “acute and transient psychotic disorder” defined by ICD-10 in its category F 23, has nothing in common with schizoaffective disorder. Nevertheless, some may mix them up. This is an acute, short-term psychosis with a favourable outcome and does not combine schizophrenic and mood episodes (for a more detailed description see).5)