Are older dads more likely to have troubled children? A wide-ranging new study suggests yes, linking older fathers to an increased risk of a wide range of mental disorders as well as lower grades in school and a higher risk of drug problems. Children born to 45-year-old fathers were more than three times as likely to be diagnosed with autism compared to children born to 24-year-olds, 13 times as likely to be diagnosed with ADHD, and 25 times more likely to be diagnosed with bipolar disorder, reports the BBC. The increased risk remained even when researchers working with the medical and public records of millions of Swedish people controlled for every other factor they could think of. "We spent months trying to make the findings go away, looking at the mother’s age, at psychiatric history, doing sub-analyses," the lead researcher says. "They wouldn’t go away."
The researchers believe the problems are linked to mutated sperm, though experts not involved with the study stress that the overall occurrence of the disorders remains low and caution strongly against would-be dads deciding against fatherhood based on one—or even multiple—studies. "This is the best paper I’ve seen on this topic, and it suggests several lines of inquiry into mental illness," a professor of genetics at the University of North Carolina tells the New York Times. "But the last thing people should do is read this and say, 'Oh no, I had a kid at 43, the kid's doomed.' The vast majority of kids born to older dads will be just fine." An expert on psychosis at Britain's Institute of Psychiatry says that while the study is "a concern" as growing numbers of people delay having children, older parents tend to have more stable relationships and higher incomes, benefits which "probably outweigh" any risks.