In what is the largest-ever international study of the link between autism and parental age, a paper, published on June 9 in the journal Molecular Psychiatry, says there is a link between parental age and potential risk factors for Autism Spectrum Disorders (ASD).
The study, which was conducted on a sample of 5,766,794 children born between 1985 and 2004 in five countries — Denmark, Israel, Norway, Sweden, and Western Australia — was funded by the advocacy group Autism Speaks. The over 5.7 million children studied were followed up with between 2004 and 2009, and of that number, 30,902 children were diagnosed with ASD, and another 10,128 were diagnosed with autism.
“There’s no other data set like this out there,” co-author Michael Rosanoff, Autism Speaks’ director of public health research, told CBS News. “We’ve seen in previous literature that older parents are at a higher risk of having a child with autism, but what we’re unsure of is if it’s the father’s age that increases the risk, if it’s the mother’s age, or if it’s both. This study was able to look at the effects of maternal age and paternal age both independently and jointly.”
Led by Dr. Sven Sandin of the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden, the study found that autism rates were 66 percent higher in children born to fathers over 50 years of age, compared to fathers who were in their 20s. ASD rates of children born to mothers in their 40s were 15 percent higher and were 18 percent higher in children born to teenage mothers, as opposed to children born of mothers in their 20s.
“These results suggest that multiple mechanisms are contributing to the association between parental age and ASD risk,” the study says.
The researchers also found that ASD rates spiked when the parental age was higher for both mother and father, as well as when there was an age gap of at least 10 years between the parents. Rates were highest, the study explains, when fathers were between the age of 35 and 44 with their partners being at least 10 years younger, and when the mothers were in their 30s, with the fathers being at least 10 years younger.
The paper also pointed out that parental age is just one potential risk factor that may contribute to the development of autism in children, and not the cause of autism itself.
“By being able to understand some of the risk factors for autism, we can better understand what may have been some of the causal factors in an individual’s autism diagnosis,” Rosanoff said, “But this study tells us about risk and not necessarily cause.”
“Although parental age is a risk factor for autism,” Dr. Sandin added, “it is important to remember that, overall, the majority of children born to older or younger parents will develop normally.”
This is not the first study to link autism and parental age, but it is certainly the largest ever conducted and may help researchers and scientists begin to pinpoint the causal factors that lead to the development of autism and all spectrum disorders, and not just the risk factors.
[Image Credit: Canadian Nanny]