Paternal and maternal age as risk factors for psychosis: findings from Denmark, Sweden and Australia

Background: While the association between increased maternal age and congenital disorders has long been recognized, the offspring of older fathers are also at increased risk of congenital disorders related to DNA errors during spermatogenesis. Recent studies have drawn attention to an association between increased paternal age and increased risk of schizophrenia. The aim of the current study was to examine both paternal and maternal age as risk factors for the broader category of psychosis. Method: We used data from three sources examining psychosis: a population-based cohort study (Denmark), and two case-control studies (Sweden and Australia). Results: When controlling for the effect of maternal age, increased paternal age was significantly associated with increased risk of psychosis in the Danish and Swedish studies. The Australian study found no association between adjusted paternal age and risk of psychosis. When controlling for the effect of paternal age, younger maternal a-e was associated with an increased risk of psychoses in the Danish study alone. Conclusions: The offspring of older fathers are at increased risk of developing psychosis. The role of paternally derived mutations and/or psychosocial factors associated with older paternal age warrants further research. (C) 2003 Elsevier B.V. All rights reserved.