Older parents and parents with an age gap of 10 years or more have a higher risk of having children with autism spectrum disorders, according to a study. The research was reported by Medical News Today.
Though there have already been previous studies on the link between paternal age and autism, this is the first to have shown results using a large sample size of over 5.7 million children (more than 30,000 of which had ASD) and a scope which spanned five countries (Australia, Denmark, Israel, Norway and Sweden).
“By linking national health registries across five countries, we created the world’s largest dataset for research into autism’s risk factors,” said co-author Michael Rosanoff, director of public health research for Autism Speaks.
“We can now say confidently that advanced paternal and maternal age is a risk factor for autism,” Rosanoff told Yahoo Parenting.
Results showed that autism prevalence was 66% higher in children born to fathers aged 50 and over, and 28% higher in children born to fathers in their 40s compared to those born to fathers who were in their 20s.
Autism prevalence was 15% higher for children born to mothers in their 40s compared to those who gave birth in their 20s. However, they also found that if the mother was in her teens, ASD rates were higher by 18%.
In addition, higher rates were also found for fathers who had the combination of being 35- to 44-years old and being 10 or more years older than the mother.
“After finding that paternal age, maternal age and parental age gaps all influence autism risk independently, we calculated which aspect was more important,” said co-author Dr. Sven Sandin. “It turned out to be parental age, though age gaps also contribute significantly.”
“In this study, we show for the first time that autism risk is associated with disparately aged parents,” said co-author Abraham Reichenberg, a neuropsychologist and epidemiologist with the Icahn School of Medicine.
Nonetheless, he added, “It is important to remember that, overall, the majority of children born to older or younger parents will develop normally.”
Researchers speculate that the reason for the higher rates for older fathers could be caused by aging sperms. For age gaps and older mothers, however, explanations are yet to be found.
The study was published in the journal Molecular Psychiatry.
Sources: June 9, 2015. "Autism risk may be influenced by age gap between parents". medicalnewstoday.com June 11, 2015. "The Type of Parents Most Likely to Have a Child with Autism". yahoo.com June 12, 2015. "Risk of autism higher for children of teenage mothers and older parents". independent.co.uk