THE CONCEPT OF ATYPICAL PSYCHOSES - SPECIAL REFERENCE TO ITS DEVELOPMENT IN JAPAN

Reviewing the development of concepts of 'atypical' psychoses in Europ ean countries and in the United States shows that there are various te rminologies which are given to a group of psychoses unclassifiable wit hin Kraepelinian dichotomy. Bouffee delirante (French school), cycloid psychoses (Leonhard, Perris), reactive psychoses (Scandinavian school ) and acute schizoaffective psychoses (Kasanin) are the most common te rms. These are consistent in terms of acute onset, polymorphic symptom atology and good prognosis, and are considered to be distinct from maj or psychoses, especially from typical schizophrenia. The concept atypi cal psychoses in Japan was developed under the influence of Mitsuda's clinico-genetic studies. According to Mitsuda, atypical psychoses are not mere phenotypical variants of typical schizophrenia and manic-depr essive psychosis (MDP) but belong to a genetically different category and are probably heterogeneous. The characteristic features in the Jap anese concept of atypical psychoses emphasizes the alteration of consc iousness in symptomatology and pays attention to the nosological relat ionship with epilepsy, as well as with schizophrenia and MDP. Thus, in Japan it is generally considered that atypical psychoses are independ ent of 'typical' major psychoses and are located nosologically in the border area between typical schizophrenia, MDP and epilepsy.