Differences in maternal and paternal age between schizophrenia and other psychiatric disorders

Advanced parental age has been shown to increase offspring risk for a number of neuropsychiatric disorders including schizophrenia and Down's syndrome. Other psychiatric disorders have been less studied with respect to the effect of parental age on offspring risk. In this study we examine if advanced parental age increased risk for ICD-10 diagnoses. We hypothesized that advanced parental age would increase risk for offspring psychotic disorders and mental retardation but not other ICD-10 diagnoses. We examined follow-up data for 30,965 subjects treated in outpatient psychiatric facilities between 1980 and 2007. Subjects were younger than 18 years of age at their first outpatient visit. A comparison group was obtained from data on registered births in Spain from 1975. We compared parental age (maternal, paternal, combined) across diagnostic categories using ANOVA and logistic regression was used to estimate the risk of psychopathology in the offspring with advanced parental age (maternal, paternal, combined). Maternal and paternal ages were higher for subjects diagnosed with mental retardation. Risk for psychotic disorders showed a significant linear increase only with advancing maternal age, and not paternal age as is more often reported.