Classifying psychosis--challenges and opportunities.

Within the efforts to revise ICD-10 and DSM-IV-TR, work groups on the classification of psychotic disorders appointed by the World Health Organization (WHO) and the American Psychiatric Association (APA) have proposed several changes to the corresponding classification criteria of schizophrenia and other psychotic disorders in order to increase the clinical utility, reliability and validity of these diagnoses. These proposed revisions are subject to field trials with the objective of studying whether they will lead to an improvement of the classification systems in comparison to their previous versions. Both a challenge and an opportunity, the APA and WHO have also considered harmonizing between the two classifications. The current status of both suggests that this goal can only be met in part. The main proposed revisions include changes to the number and types of symptoms of schizophrenia, the replacement of existing schizophrenia subtypes with dimensional assessments or symptom specifiers, different modifications of the criteria for schizoaffective disorder, a reorganization of the delusional disorders and the acute and transient psychotic disorders in ICD-11, as well as the revision of course and psychomotor symptoms/catatonia specifiers in both classification systems.