Paternal and maternal ages have contrasting associations with self-reported schizophrenia liability

Background: Older paternal age predicts schizophrenia diagnosis in offspring. If this relationship reflects a pathogenic process, paternal age should predict the expression of subclinical schizophrenia liability (schizotypy). We hypothesized that paternal and maternal ages predict positive, negative, and disorganized features of schizotypy, that family history of psychosis moderates the relationship of paternal age with schizotypy, and that stress sensitivity mediates the relationship of maternal age with schizotypy. Method: Two studies are reported, each of undergraduates (n = 500 and n = 211) who completed the Schizotypal Personality Questionnaire. The second was designed to replicate and extend the first and included assessment of stress sensitivity. Results: In Study 1, older paternal age and younger maternal age predicted greater positive schizotypy (beta = .13 and beta = -.19, respectively). Parental ages did not predict negative or disorganized features and family history did not moderate the paternal age association. In Study 2, the same pattern of associations between parental ages and schizotypy components was observed. Additionally, stress sensitivity partially mediated the association of maternal age with positive schizotypy whereas it did not contribute to the paternal age association. Conclusion: The association between older paternal age and schizophrenia extends to self-reported positive features of schizophrenia liability, consistent with the notion that this relationship arises from a pathogenic process, such as de novo mutations. Importantly, younger maternal age was an equally potent predictor of positive schizotypy, with its association partially mediated by stress sensitivity.