Historical and conceptual features of acute polymorphic psychosis: a myth of European psychiatry from to ICD-11 acute and transient psychotic disorder.

This paper deals with the history and epistemology of acute polymorphic psychosis. We undertook a comparative study of short-lived psychotic disorders used in different European countries since the late nineteenth century. The theory of degeneration offered a speculative basis to conceptualization of conditions such as , cycloid psychosis and reactive psychosis, but it seems likely that different factors contributed to the profusion of clinical concepts with adverse effects on both nomenclature and classification. The resulting picture suggests that earlier nosological concepts tend to converge on common descriptive features and challenge the diagnostic categories for short-lived psychotic disorders listed in modern symptom-based psychiatric classifications.