Schizophrenia and other psychotic disorders in diagnostic and statistical manual of mental disorders (DSM)-5: Clinical implications of revisions from DSM-IV

Byline: Rajiv. Tandon Our current systems of classifying psychiatric disorders (Diagnostic and Statistical Manual of Mental Disorders [DSM] and International Classification of Diseases [ICD]) have evolved over the past 60 years from the first edition of the DSM (DSM-1) [sup][1] to the current DSM-5 [sup][2] and from the sixth revision of the ICD (ICD-6) [sup][3] to the current ICD-10. [sup][4] Each revision has sought to incorporate new knowledge about various psychiatric disorders, improve reliability and validity, provide diagnostic clarity and enhance clinical utility. In addition, DSM-5 sought to address limitations in the DSM-IV definitions of various disorders; with regard to psychotic disorders, these included: [sup][5] (i) Unclear boundary between schizoaffective disorder and schizophrenia; (ii) variable definitions and discrepant treatment of catatonia across DSM-IV manual; (iii) poor description of clinical heterogeneity of schizophrenia and other psychotic disorders; (iv) spurious comorbidity of delusional disorder and obsessive-compulsive disorder; (v) poor reliability and low diagnostic stability of the diagnosis of schizoaffective disorder; and (vi) inappropriate special treatment of Schneiderian first-rank symptoms ("bizarre" delusions or "special" hallucinations) in the definition of schizophrenia. Revisions in DSM-5 sought to address these limitations, while incorporating new information about various psychotic disorders generated since the publication of DSM-IV in 1994. In addition, revisions were intended to enhance clinical utility by reducing unnecessary complexity and improving coherence across this group of disorders. The major revisions in the definition of schizophrenia and other psychotic disorders from DSM-IV to DSM-5 are summarized along with the implications of these changes for clinical practice. Schizophrenia In view of its fair validity and clinical utility, changes in the diagnostic criteria of schizophrenia are relatively modest, and broad continuity with DSM-IV is maintained. The significant heterogeneity of the schizophrenias is, however, poorly explained by DSM-IV and consequently, major changes in this regard were made in DSM-5. The special treatment of bizarre delusions and other Schneiderian first-rank symptoms in criterion A (active phase symptoms) is eliminated because these symptoms have not been found to be specific for schizophrenia and the distinction between bizarre versus nonbizarre delusions has been found to have poor reliability. [sup][6] These symptoms lack any special significance in the context of schizophrenia. In DSM-5, "Schneiderian first-rank symptoms" are treated like any other positive symptom with regard to their diagnostic implication : t0 wo criterion A symptoms will be required even if one of them is a bizarre delusion. The impact of this change on clinical practice will be limited because A second change is the addition of a requirement that at least one of the two required symptoms to meet criterion A be delusions, hallucinations, or disorganized thinking. These are core "positive symptoms" and should be necessary for a reliable diagnosis of schizophrenia. [sup][8] Again, this change will have negligible impact on clinical practice as One major change in DSM-5 will be the elimination of the classic subtypes of schizophrenia. These subtypes have limited diagnostic stability, low reliability, poor validity, and little clinical utility. …