Ageing and psychosis
The classiﬁcation of psychotic disorders in later life remains an area which lacks clarity. The terms late-onset (or very-late-onset) schizophrenia and paraphrenia are both sometimes used for people who develop a new psychotic illness in later life. The International LateOnset Schizophrenia Group in 1998 (Howard et al. 2000) produced a consensus statement which recognised late-onset schizophrenia (with onset after the age of 40 years) and very-late-onset schizophrenia-like psychosis (with onset after the age of 60 years). The Group regarded typical-onset schizophrenia as having an age of onset between 15 and 40 years. The group of disorders described by the term very-late-onset schizophrenialike psychosis is sometimes still called paraphrenia by practising old age psychiatrists. The International Classiﬁcation of Diseases (ICD)-10 classiﬁes the paraphrenias as
persistent delusional disorders (F22.0) (World Health Organization 2007). ICD-10 requires delusions to be the only, or the most prominent, feature of the clinical presentation and to have been present for at least three months. It describes the disorders as ‘persistent and sometimes lifelong’ and notes that persistent auditory hallucinations or evidence of organic brain disease are incompatible with the diagnosis. In practice old age psychiatrists often use late-onset schizophrenia to describe ill-
nesses which start in later life (aged over 60 or 65) but would fulﬁl diagnostic criteria for schizophrenia, and paraphrenia to describe psychosis with onset in later life with prominent delusions which would not fulﬁl strict diagnostic criteria for schizophrenia. In this chapter, for simplicity, this is the terminology which will be used.