[Schizoaffective disorder: An arguable diagnostic entity].
Seventy-five years ago, J. Kasanin introduced the term "schizoaffective disorder" to refer to a disorder with symptoms of both schizophrenia and affective disorders. Since then, schizoaffective disorder has raised a considerable amount of discussion about its definition and position as a variant of  schizophrenia, a variant of mood disorder or as an entity in between. This ambiguity is reflected on  the definition of diagnostic criteria of the disorder in the taxonomic systems, which are practically  too complex. Furthermore, there are essential differences between DSM-IV and ICD-10 regarding  schizoaffective definition. Finally, the disorder has a very low inter-rater reliability and a very low  longitudinal diagnostic stability. All the above have even led to proposals of elimination of schizoaffective disorder as a separate diagnostic entity. The prevalence of the disorder varies between 0.3%  and  0.8%.  Schizoaf fective  disorder  is  more  common  in  women  than  in  men,  a  dif ference  that  is  mostly attributed to increased incidence among women of the depressive type. The bipolar type  of the disorder is more often found in young adults, whereas the depressive type is commoner in  older adults. With regards to other variables such as educational level, marital status, prognosis, occupational level and social adjustment, schizoaffective disorder has more favourable characteristics  than schizophrenia and less favourable than mood disorders. Age at onset is earlier than mood disorders and later than schizophrenia. The above epidemiologic and clinical data, as well as data from  family, twin, genetic and neuroimaging studies, indicate that schizoaffective disorder can be best  viewed as a mid-point on a continuum between schizophrenia and mood disorders and represents  the most prominent paradigm challenging the so-called "Kraepelinian dichotomy" of major psychiatric disorders. Though schizoaffective disorder is a nosological nuisance, it is also a clinical reality  and it is not advisable to abandon it as a separate diagnosis.
2nd University Department of Psychiatry, Aristotle University of Thessaloniki, Thessaloniki, Greece.
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Garyfallos