Autism Researchers Say Nearly Half of Baby Siblings Show Delays at 12 Months

Date: 
March 10, 2014
Investigators urge close monitoring and early intervention for developmental issues among infant siblings of children with autism


Researchers in Autism Speaks Baby Siblings Research Consortium report that they can detect developmental problems at 12 months in nearly half of children who have an older brother or sister with autism spectrum disorder (ASD).

"This research should give parents and clinicians hope that clinical symptoms of atypical development can be picked up and addressed earlier,” says lead author Sally Ozonoff. Dr. Ozonoff is a professor of psychiatry and behavioral sciences at the MIND Institute of the University of California, Davis. Her team’s study appears online in the Journal of the American Academy of Child and Adolescent Psychiatry.

Earlier research by the consortium showed that around 1 in 5, or 20 percent, of children who have an older sibling with autism will themselves develop the disorder. That autism tends to run in families is due, at least in part, to inherited gene changes that predispose to the disorder.

Less clear has been what early developmental issues affect children who have an older sibling with autism but who do not go on to develop the disorder. The new study was designed to address this question.

The researchers enrolled 294 infant siblings of children with autism. For comparison, they enrolled 116 infant siblings of children with typical development. They began tracking the children’s development at 6 to 12 months. They assessed the children again at 18, 24 and 36 months using standard tests for developmental delays and autism.

Nearly Half Diagnosed with ASD or Show Related Issues
By 36 months, 17 percent of the baby siblings of children with autism had been diagnosed with ASD. Another 28 percent had related developmental issues that fell short of an ASD diagnosis. Most commonly, these included problems with communication and social behaviors such as extreme shyness and relatively little eye contact or use of pointing to convey interest.

Also noteworthy: The baby siblings who showed early delays didn’t “catch up” over time. This counters the traditional wait-and-see approach still common among many healthcare providers.

“In families that already have a child with autism, there is clearly a continuum that involves not just ASD but other developmental concerns,” comments Alycia Halladay, Autism Speaks senior director for environmental and clinical sciences. “These siblings, while not having an autism diagnosis, still may need clinical services and intervention.” 

Dr. Halladay joins the UC-Davis investigators in urging parents, pediatricians and other caregivers to be vigilant for early delays and to take advantage of targeted early intervention therapies that can improve crucial early skills as well as long-term outcomes.

Also see: Learn the Signs and Screen Your Child.

Autism Speaks Baby Siblings Research Consortium brings together research groups with the mission of discovering the earliest predictors of autism. Their collaboration is advancing understanding of how autism develops and how it can be diagnosed and treated earlier. Read more about this important research and its findings here.