A CONTROLLED FAMILY STUDY OF LATE-ONSET NONAFFECTIVE PSYCHOSIS (LATE PARAPHRENIA)

Background The relationship between those schizophrenia-like condition s that have their onset in late life and early-onset schizophrenia is unclear. Very few family history studies of patients with late-onset p sychosis have been reported, and it is rot known whether their relativ es have an increased risk of psychosis. Method Information was collect ed on the psychiatric morbidity of 269 first-degree relatives of patie nts with schizophrenia-or delusional disorder with an onset after the age oi 60 (late paraphrenia), and 272 first-degree relatives of health y elderly control subjects, using a research diagnostic instrument. Re sults With a narrow age range (15-50 years) at risk, the estimated lif etime risk of schizophrenia was 1.3% in the relatives of both cases an d controls. With a wider age range (15-90 years) at risk, estimated li fetime risk of schizophrenia was 2.3% for the relatives of cases, and 2.2% for the relatives of controls. However, depression was significan tly more common among the relatives of cases than controls. Conclusion Those schizophrenia-like psychoses with onset in late life are not ge netically associated with schizophrenia.