For almost 10 years, studies have shown that advanced paternal age may be a risk factor for schizophrenia in offspring. However, the risk of schizophrenia may also be higher in male offspring of fathers who are younger than 25 years, according to the results of a study presented at the 2009 American Psychiatric Association annual meeting.
“An increased risk associated with younger fathers raises the possibility of different causal mechanisms for schizophrenia between this group and for offspring of older fathers,” said Brian Miller,1 lead study author and a fellow in the department of psychiatry at the Medical College of Georgia in Augusta.
Miller and colleagues from universities in Finland and London conducted a meta-analysis of both published and unpublished data on paternal age and schizophrenia in offspring. “We performed a meta-analysis in order to better estimate the effect size of this association, considering the effects of gender and study design,” said Miller.
Incidence of schizophrenia was lowest in offspring of fathers aged 25 to 30 years. Compared with this group, the population attributable risk was found to be 10% higher for paternal age of 30 years or older and 4% higher for paternal age younger than 25 years.
Results confirmed that there is a significantly higher increase in risk of schizophrenia in the offspring of fathers older than 30 years, and there was no evidence of sexual dimorphism. According to Miller, the risk of schizophrenia in the offspring of fathers older than 30 is a significant public health concern, because average paternal ages are increasing.