(RxWiki News) You may have heard that an older mom's age may influence her child's risk for autism, but babies born to teen moms and older dads may also be at risk.
A new study found that autism rates increased among children born to teen moms, children born to older parents and among children whose parents had large gaps between their ages.
"Though we've seen research on autism and parental age before, this study is like no other," said co-author and Director of Public Health Research for Autism Speaks, Michael Rosanoff, MPH, in a press release. "By linking national health registries across five countries, we created the world's largest data set for research into autism's risk factors."
Still, Bradley R. Berg, MD, PhD, division director of pediatrics at Baylor Scott and White in Austin and Round Rock, advised caution.
"... I think it would be a mistake for providers to start counseling parents that there is a 'correct or optimal' time to have children," Dr. Berg told dailyRx News. "This is a relative risk study and basically says that advanced parental ages have about 5X the risk of having an autistic child compared to the general population, which is around 1 percent. Thus, older couples have a 5 percent chance of having a ASD child, which is still low. Counseling parents not to have children because they are older and MIGHT have a child with ASD would be premature at this point."
Autism, formally known as autism spectrum disorder (ASD), is a group of developmental disorders that includes Asperger's syndrome and several other disorders. These disorders can cause significant social, communication and behavioral challenges. The mental abilities of patients with ASD can range from gifted to severely challenged. Some patients with ASD need a lot of help in their daily lives, while others need less.
Males are four times more likely to have ASD than females, according to the National Institute of Neurological Disorders and Stroke (NINDS). The Centers for Disease Control and Prevention (CDC) reports that about 1 out of every 88 children in the US has some form of ASD.
ASD is thought to result from a combination of genetics and environment. Although treatments are available, there is no cure for ASD.
Rosanoff and colleagues looked at data on more than 5.7 million children in five countries (Denmark, Israel, Norway, Sweden and Australia) — and more than 30,000 children with autism born between 1985 and 2009 in these countries.
Past studies found links between parental age and the risk of autism in children. However, this study was the first to break down how parental age in both men and women may increase autism risk.
"After finding that paternal age, maternal age and parental-age gaps all influence autism risk independently, we calculated which aspect was most important," said study co-author and medical epidemiologist Sven Sandin, PhD, of the Karolinska Institutet, in the release. "It turned out to be parental age, though age gaps also contribute significantly."
Dr. Sandin and colleagues found that the autism rate was 66 percent higher in children fathered by men in their 50s or beyond — compared to children fathered by men in their 20s.
The autism rate was also 15 percent higher in children born to mothers in their 40s and beyond and children born to mothers in their teens — compared to those born to mothers in their 20s.
When both parents were older, autism rates also increased.
These researchers found that — while age affects autism risk — the age gap between the parents may also play a part. When the gap between parents’ ages was 10 years or more, autism rates went up.
Dr. Sandin and colleagues found that children born to fathers between the ages 35 to 44 whose partners were 10 or more years younger had the highest rates of autism.
According to these researchers, these higher rates in older men may be due to genetic mutations in sperm — which increase with age.
"Although parental age is a risk factor for autism, it is important to remember that, overall, the majority of children born to older or younger parents will [not develop autism]," Dr. Sandin said.
This study was published in the June issue of the journal Molecular Psychiatry.
Autism Speaks, a nonprofit autism advocacy organization, funded this research.
No conflicts of interest were disclosed.