Psychosis is the phenotypic expression of advanced parental age (APA) in the schizophrenia-bipolar disorder, according to a study of 12,975 subjects with a schizophrenia-bipolar disorder diagnosis or unaffected controls. The study estimated the relative risk ratios for schizophrenia, schizoaffective depressed and bipolar types, and bipolar disorder with and without history of psychotic features relative to the control group, comparing each paternal age group to the reference group of aged 20 to 24 years. Researchers found:
• Subjects with fathers aged 45 and older had significantly higher risk for all diagnoses expect for bipolar disorder without psychotic features.
• APA had no significant relation to family psychiatric history.
• Underlying mechanisms of the paternal age effect may involve a complex interaction of heritable and non-heritable factors.
Citation: Lehrer DS, Pato MT, Nahhas RW, et al. Paternal age effect: Replication in schizophrenia with intriguing dissociation between bipolar with and without psychosis. Am J Med Genet B Neuropsychiatr Genet. [Published online ahead of print, July 16, 2015]. doi: 10.1002/ajmg.b.32334.