February 26, 2014

Science Daily/Indiana University

Advancing paternal age can lead to higher rates of psychiatric and academic problems in offspring than previously estimated. Compared to a children born to a 24-year-old father, children born to a 45-year-old father are 3.5 times more likely to have autism, 13 times more likely to have ADHD, twice as likely to have psychotic disorders and 25 times more likely to have bipolar disorder.

Examining an immense data set -- everyone born in Sweden from 1973 until 2001 -- the researchers documented a compelling association between advancing paternal age at childbearing and numerous psychiatric disorders and educational problems in their children, including autism, ADHD, bipolar disorder, schizophrenia, suicide attempts and substance abuse problems. Academic problems included failing grades, low educational attainment and low IQ scores.

Among the findings: When compared to a child born to a 24-year-old father, a child born to a 45-year-old father is 3.5 times more likely to have autism, 13 times more likely to have ADHD, two times more likely to have a psychotic disorder, 25 times more likely to have bipolar disorder and 2.5 times more likely to have suicidal behavior or a substance abuse problem. For most of these problems, the likelihood of the disorder increased steadily with advancing paternal age, suggesting there is no particular paternal age at childbearing that suddenly becomes problematic.

"We were shocked by the findings," said Brian D'Onofrio, lead author and associate professor in the Department of Psychological and Brain Sciences in the College of Arts and Sciences at IU Bloomington. "The specific associations with paternal age were much, much larger than in previous studies.

In fact, we found that advancing paternal age was associated with greater risk for several problems, such as ADHD, suicide attempts and substance use problems, whereas traditional research designs suggested advancing paternal age may have diminished the rate at which these problems occur."

This study and others like it, however, perhaps signal some of the unforeseen, negative consequences of a relatively new trend in human history. As such, D'Onofrio said, it may have important social and public policy implications. Given the increased risk associated with advancing paternal age at childbearing, policy-makers may want to make it possible for men and women to accommodate children earlier in their lives without having to set aside other goals.

"While the findings do not indicate that every child born to an older father will have these problems," D'Onofrio said, "they add to a growing body of research indicating that advancing paternal age is associated with increased risk for serious problems. As such, the entire body of research can help to inform individuals in their personal and medical decision-making."