Researchers say that an increasing number of genetic mutations in men's sperm as they age could be contributing to a greater risk of autism and other disorders in children born to older fathers. (Shutterstock)

Researchers say that an increasing number of genetic mutations in men’s sperm as they age could be contributing to a greater risk of autism and other disorders in children born to older fathers. (Shutterstock)

A large new study is adding to mounting evidence tying older fathers to an increased risk of having children with autism and other disorders.

Children born to 45-year-old fathers are three-and-a-half times more likely to have autism than those born to 24-year-old dads, according to the findings published Wednesday in the journal JAMA Psychiatry.

For the study, researchers examined records for everyone born in Sweden between 1973 and 2001, totaling more than 2.6 million people.

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In addition to an increased risk for autism, they found that the likelihood of a child developing attention deficit hyperactivity disorder is 13 times greater while the odds of bipolar disorder is 25 times higher for those born to 45-year-old dads compared to fathers at age 24. The older dads were also associated with an increased risk of having children with psychotic disorder, suicidal behavior and substance abuse problems, among other issues.

In most cases, the risk for disorders in children rose steadily as fathers aged, the researchers found.

“We were shocked by the findings,” said the study’s lead author Brian D’Onofrio of Indiana University. “The specific associations with paternal age were much, much larger than in previous studies.”

The findings held even when the researchers controlled for factors like parental education and income levels, the study said. What’s more, researchers said they were able to compare the experiences of siblings and first-cousins to determine whether other factors — outside of paternal age — could be influencing their results.

While there have long been concerns about the impact of older mothers on the health outcomes of their children, research is increasingly pointing to the role that a father’s age plays in a child’s risk for various disorders.

D’Onofrio and his colleagues say that the link between paternal age and the risk for psychiatric disorders may have to do with an increasing number of genetic mutations in men’s sperm as they age.

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