Advanced paternal age increases the risk of schizophrenia and obsessive–compulsive disorder in a Chinese Han population

Using the Structured Clinical Interview for DSM-IV, patient and non-patient version (SCID-P/NP), this study investigated 351 patients with schizophrenia, 122 with obsessive–compulsive disorder (OCD), and 238 unrelated healthy volunteers in a Chinese Han population. The relative risks posed by advanced paternal age for schizophrenia and OCD in offspring were computed under logistic regression analyses and adjusted for the participant's sex, age and co-parent age at birth. Compared to the offspring with paternal age of 25–29 years old, the relative risks rose from 2.660 to 10.183 in the paternal age range of 30–34 and ≥ 35. The relative risks for OCD increased from 2.225 to 5.413 in 30–34 and ≥ 35. For offspring with paternal age of < 25, the odds ratios of developing schizophrenia and OCD were 0.628 and 0.289 respectively, whereas an association between increased maternal age and risk for schizophrenia/OCD was not seen. Interaction analysis showed an interaction effect between paternal age and maternal age at birth. Such a tendency of risk affected by parental age for schizophrenia and OCD existed after splitting out the data of early onset patients. Sex-specific analyses found that the relative risks for schizophrenia with paternal age of 30–34 and ≥ 35 in male offspring were 2.407 and 10.893, and in female offspring were 3.080 and 9.659. The relative risks for OCD with paternal age of 30–34 and ≥ 35 in male offspring were 3.493 and 7.373, and in female offspring 2.005 and 4.404. The mean paternal age of schizophrenia/OCD patients born before the early 1980s was much greater than that of patients who were born after then. The findings illustrated that advanced paternal age is associated with increased risk for both schizophrenia and OCD in a Chinese Han population, prominently when paternal age is over 35. Biological and non-biological mechanisms may both be involved in the effects of advanced paternal age on schizophrenia and OCD.