Delayed fatherhood not a factor in schizophrenia, bipolar disorder risks in offspring
Advanced paternal age does not contribute to increased risks of schizophrenia and bipolar disorder in the offspring, a study reports.
The study included a cohort of 916,439 individuals, among whom 4,488 had schizophrenia and 883 had bipolar disorder. Researchers used logistic regression models to examine the relationship of paternal age with the risk of later hospitalizations for schizophrenia or bipolar disorder.
Results revealed a statistically significant increase in schizophrenia risk with advancing categories of paternal age. Individuals whose fathers were aged 45–60 years at birth had the highest risks of schizophrenia (adjusted odds ratio [aOR], 1.49; 95 percent CI, 1.27–1.75) and bipolar disorder (aOR, 1.68; 1.18–2.39).
Advanced paternal age was associated with an increased risk of schizophrenia, with the association remaining significant after further adjustments for maternal age at birth and year of birth among others. On the other hand, the association observed with the risk of bipolar disorder disappeared after further adjustments.
In an analysis including paternal age at birth of the first-born child as a covariate, advanced paternal age at birth of a subsequent child did not contribute to heightened risks of schizophrenia and bipolar disorder.
Conditional logistic regression analysis involving participants who had a sibling with schizophrenia in the family, in order to control for potential familial confounding, showed that advanced paternal age was associated with an increased risk of neither schizophrenia within the 3,876 families of discordant sibling pairs nor risk of bipolar disorder within the 2,287 discordant sibling pairs.
The present data do not support the hypothesis that de-novo mutations underlie the association between advanced paternal age and schizophrenia and bipolar disorder, researchers said. One potential explanation might be that psychosocial characteristics of fathers with delayed initial fatherhood may predispose their offspring to schizophrenia and bipolar disorder.