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.

Key words: Schizoaffective disorder, diagnosis, epidemiology, “Kraepelinian dichotomy”

G.D. Garyfallos (page 205) - Full article (Greek)