Tuesday, April 22, 2014

Autism is Tied to Parental Age, Especially Maternal Age


Older parents are more likely to have a child who develops an autism spectrum disorder (ASD) than are younger parents. A recent study from researchers from the Drexel University School of Public Health in Philadelphia and Karolinska Institute in Sweden provides more insight into how the risk associated with parental age varies between mothers' and fathers' ages, and found that the risk of having a child with both ASD and intellectual disability is larger for older parents.

In the study, published in the February 2014 issue of the International Journal of Epidemiology, researchers report that fathers' and mothers advancing ages have different impacts on their child's risk. The rise in ASD risk with parental age was greater for older mothers as compared to older fathers.

"The open question at hand really is, what biological mechanisms underlie these age effects?" said Brian K. Lee, PhD, an assistant professor in the Drexel University School of Public Health and research fellow of the A.J. Drexel Autism Institute, and senior author of the study. The observed differences in risk based on mothers' and fathers' ages point to a need to continue investigating underlying mechanisms of ASD that may be influenced by a mother's age, Lee said, even though much recent discussion has focused on fathers' and even grandfathers' ages.

The risk of having a child with ASD had a more complicated relationship to age in women than in men – whose risk of fathering a child with ASD increased linearly with age across their lifespan. Among women giving birth before the age of 30, the risk of ASD in the child showed no association with age -- it was simply very low. But for babies born to mothers aged 30 and older, the chance of developing ASD rose rapidly with the mother's age.

Lee noted that the non-linear maternal age effect that is relatively stronger than the paternal age effect on ASD risk has been observed in previous studies, but has not received much attention.

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