Influenza epidemics and incidence of schizophrenia, affective disorders and mental retardation in Western Australia: No evidence of a major effect

Abstract

In-utero exposure to influenza has been implicated as a risk factor for developmental CNS damage. This study tests the hypothesis that in-utero exposure to influenza: (1) in the second gestational trimester is associated with an increased risk of schizophrenia and affective psychoses; and (2) in the first gestational trimester is associated with an increased risk of mental retardation. Analysis was confined to 1852 eases on the Western Australian psychiatric case register with ICD-9 diagnoses of schizophrenia, affective psychoses, or neurotic depression (comparison group), and 804 cases on the Intellectual Handicap Register with mental retardation that were related to 82 963 'exposed' and 32..