Late-onset schizophrenia and very-late-onset schizophrenia-like psychosis: an international consensus. The International Late-Onset Schizophrenia Group.

OBJECTIVE: Although schizophrenia is generally regarded as an illness with onset in late adolescence or early adult life, a sizeable minority of patients first become ill in middle or old age. Inconsistencies in diagnostic systems and nomenclature, coupled with a tendency among most schizophrenia researchers to ascribe late-onset psychoses to organic factors, have led to such cases occupying an ambiguous position in relation to schizophrenia. Through systematic review of the literature and publication of a consensus statement from an international group of experts in the field, this article aims to clarify the positions of late-onset schizophrenia and very-late-onset schizophrenia-like psychosis. METHOD: The authors conducted a MEDLINE literature review and developed a consensus statement summarizing the findings from 2 days of debate and discussion by members of the International Late-Onset Schizophrenia Group. RESULTS: The group achieved consensus on diagnosis, nomenclature, treatment guidelines, and future research directions. CONCLUSIONS: In terms of epidemiology, symptom profile, and identified pathophysiologies, the diagnoses of late-onset schizophrenia (illness onset after 40 years of age) and very-late-onset schizophrenia-like psychosis (onset after 60 years) have face validity and clinical utility. General adoption of these categories will foster systematic investigation of such patients.