Conceptual Issues in Acute and Transient Psychotic Disorders.

Short-lived psychotic disorders as currently listed under "acute and transient psychotic disorder," ICD-11 Classification of Mental, Behavioural, and Neurodevelopmental Disorders, and "brief psychotic disorder," Diagnostic and Statistical Manual of Mental Disorders (DSM-5), constitute a point of divergence in the classification of psychotic disorders between the 2 diagnostic systems, which reveals the lack of knowledge about these conditions. Whether this is due to conceptual shortcomings inherent to the categories themselves and which spill over onto research or reflects a mismatch between the diagnostic criteria used and research techniques needs clarification. This study aimed to examine conceptual issues involved in the development of the above categories and shows that little continuity exists between earlier nosological concepts such as bouffee delirante, cycloid psychosis, and reactive psychosis and modern descriptive categories used to classify short-lived psychotic disorders. It seems likely that shortcomings in terms of symptom completeness, specificity, and heterogeneity, in addition to changes in definition and diagnostic criteria in successive DSM and ICD versions, have hampered empirical research, making it difficult to enhance the understanding of these conditions and achieve a closer concordance between the 2 classificatory systems.