Skip navigation

Calls to Action

Development in Younger Siblings: Beyond Autism

May 16, 2012

Last year, researchers with the Autism Speaks Baby Siblings Research Consortium reported that the younger siblings of children with autism have a nearly 1 in 5 chance of likewise developing an autism spectrum disorder (ASD). While this is an important finding, it does not address the outcomes of the majority of younger siblings – those who don’t develop autism.

Today, these same researchers report their follow-up findings on 508 younger siblings who did not develop ASD. Just over a third (35 percent) fell into groups with some autism behaviors or some slowing in reaching their developmental milestones at age three. By comparison, such behaviors and delays affected fewer than 18 percent of 324 3-year-olds from families unaffected by autism.

The study found that younger siblings of children with ASD had lower levels of verbal and nonverbal functioning. They also had higher levels of autism-related symptoms. These problems, though not as severe as children with an ASD, included less back-and-forth play with others and lower levels of pointing to express interest in what is going on around them.

The report was presented today at the 2012 International Meeting for Autism Research (IMFAR), in Toronto. A grant from Autism Speaks allowed the researchers to analyze information from twelve research groups in the Baby Siblings Research Consortium.

“For good reason, parents who have a child with autism are concerned about the development of younger siblings,” says Alycia Halladay, Ph.D., Autism Speaks director for environmental research. Halladay helped organize and continues to work closely with the Baby Siblings Research Consortium. “Knowing that a younger sibling is at risk for autism or other developmental issues will encourage parents and healthcare providers to more closely monitor developmental milestones to promote earlier detection and intervention,” she explains. (See Learn the Signs.)

Importantly, 65 percent of the younger siblings showed typical or above average development and few or no autism symptoms. By comparison, this was true for more than 80 percent of the group from families unaffected by autism.

The lead author of the report was Daniel Messinger, Ph.D., of the University of Miami. Supported by Autism Speaks, the Baby Siblings Research Consortium is an international network that coordinates studies and pools information from 21 autism research programs in the U.S., Canada, Israel and the U.K.

Autism Speaks is currently funding a number of Baby Siblings Research Consortium studies. You can explore these and other Autism Speaks-funded research using our Grant Search. This research would not be possible without the support of our community of families, donors and volunteers.

For more news and commentary, please see our 2012 IMFAR page