Autism Speaks, an organization advocating for autism, had funded the largest ever international study that reveals how parents' age affects their children's autism risk.
The study, published in the journal "Molecular Psychiatry", has a wide sample. Researchers examined national health records of over 5.7 million children from Denmark, Israel, Norway, Sweden and Western Australia.
Michael Rosanoff, Autism Speaks director of public health research and co-author of the study, told CBS NEWS, "There's no other data set like this out there."
Rosanoff admitted that old literature already gave them an idea how the advanced age of parents influence the autism risk of their children. However, they cannot tell whether it was the mother's age, father's age or both parent's age which increased the child's risk to autism. The recent study addressed this concern, showing the effects of maternal and paternal age to autism risk, independently and jointly.
Dr. Holly Philipps told CBS NEWS that children among fathers in their 50s and 40s have 66 percent and 28 percent autism risk, respectively, compared to fathers in their 20s. Children from teen mothers have 18 percent risk to autism, while those from mothers in their 40s have 15 percent risk versus mothers in their 20s.
The study also revealed that age gap among couples is another factor. The research shows that when the difference of ages reaches at least 10 years, the child's risk for autism increases. The risk showed persists among fathers between the ages 35 and 44 years old, with a partner 10 years younger than them. This also applies to mothers between 30 and 39 years old, with partners at least 10 years their junior.
Past research revealed that autism risk is higher among children with older fathers. The study suggested that genetic mutation from the father's aging sperm could be associated to autism development. However, the findings only led to more questions, said Sven Sandin, author of the study, U.S. News reported.
"But it does suggest that degrading sperm is not likely to be the only mechanism that explains the relation between age of parents and autism. Other mechanisms are likely to be involved," he added.
Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Cohen's Children Medical Center of New York in New Hyde Park, corresponds that the genetic mutation from aging fathers could be the cause of a child's increasing risk of autism.
However, Adesman added, "It is unclear why there is an increased risk of autism spectrum disorders in young moms or in couples with a big age difference."
