A child born to a father 45 or older is three and a half times more likely to be diagnosed with autism, more than 13 times more likely to have attention deficit and hyperactivity disorder (ADHD), and almost 25 times more likely to suffer from bipolar disorder than a child born to a man in his early twenties, says a study out this week.
Suicide attempts and substance use problems were also found to be more than twice as common in children born to older fathers than those with younger dads, and rates of academic failure -- staying back a grade -- and low educational attainment were higher in those with older fathers than in those with younger ones.
The new research, published online first in JAMA Psychiatry, used a Swedish database that tracked more than 2.6 million children born between 1973 and 2001 to flesh out the effects of advanced paternal age on the mental health and academic success of those men's children.
As the age of childbearing couples increases throughout the developed world, the study's findings reinforce concern that men, too, have biological clocks: The sperm of older men show greater rates of spontaneous genetic mutation. And as the father's age increases, the DNA of a newborn child is more likely to show such spontaneous mutations (a factor, for instance, in many cases of autism). Past studies have found higher-than-expected rates of autism, bipolar disorder, schizophrenia and intellectual and academic problems among children born to older fathers.
The authors of the study -- from Indiana University and the Karolinska Institute in Sweden -- refined their findings by recasting their data seven different ways. They compared siblings born years apart, laid cousins side-by-side to take account of family mental health histories, and adjusted for a mother's advanced age as well. The results show disparities in the mental health and academic achievement of children born to younger and older fathers that are as large or larger than those found in past studies.
Although the authors of the study acknowledge their findings do not establish a causal link between a father's age and a child's emotional and academic vulnerability, they conclude that their findings are consistent with the hypothesis that more frequent mutations in the sperm of older men is "causally related" to their childrens' higher risk of poor outcomes.