According to the study, the researchers examined 5.7 million children and analysed that large parental age gap between the parents increases risk of developing autism spectrum disorder (ASD).
"In this study, we show for the first time that autism risk is associated with disparately-aged parents. Future research should look into this to understand the mechanisms," said study co-author Abraham Reichenberg, neuropsychologist and epidemiologist with the Icahn School of Medicine at Mount Sinai, in New York City.
The researchers examined the children for autism diagnosis who were born between 1985 and 2004 and also followed up on their development until 2009. They analysed that autism rates were 66 percent higher among children born to fathers over 50 years of age than among those born to fathers in their 20s. Autism rates were 28 percent higher when fathers were in their 40s versus 20s.
When compared to the children who born to mothers in their 20s, the autism rates were 15 percent higher in children born to mothers in their 40s. Autism rates were 18 percent higher among children born to teenage mothers than among those born to mothers in their 20s.
The autism rates rose still higher when both parents were older, in line with what one would expect if each parent's age contributed to risk.
With the widening gap between the parents, the autism rates were also increased. "These results suggest that multiple mechanisms are contributing to the association between parental age and ASD risk," the authors concluded. The study was published in the journal Molecular Psychiatry.