The infant sibling study: Finding the earliest possible clues to autism

Sally Ozonoff with study participant and mother © UC Regents
Sally Ozonoff with baby Jack Hill and mom Monique Hill

Posted Jan. 20, 2010

A cutting-edge UC Davis MIND Institute research project, the Infant Sibling Study, is leading the way in identifying early behavioral manifestations of autism by studying the younger siblings of children already diagnosed with the disorder. For reasons that are not entirely clear, these children are among the most likely to be subsequently diagnosed with the condition. While the chance that a first child will have autism is about 1 in 100, the chance that a sibling of a child with autism will also have autism is as high as 1 in 5.

The study has as its premise that as important as determining whether a child has autism is when the diagnosis is received. A child who is diagnosed early has the best possible chance of receiving intensive early intervention, such as applied behavioral analysis and speech therapy, and achieving his or her full potential.

The study is led by MIND Institute faculty member Sally Ozonoff, a professor and vice chair for research in psychiatry and behavioral sciences and a leading researcher in the field of early identification of autism signs and symptoms.

This ongoing study began in 2003. During the first five years, the study compared approximately 180 siblings of children diagnosed with autism to typically developing children on a wide array of behavioral tasks. Children were tested at two study sites, the MIND Institute and UCLA. Researchers studied early emotional development, imitation, parent-child interactions, communication, social interest, and face- and object-processing, among other behaviors.

As a result of this early research, Ozonoff and her colleagues determined that there is a much higher rate of “adverse developmental outcomes” in siblings of children diagnosed with autism spectrum disorders (ASD) than had previously been suggested. While earlier estimates placed the risk of having a second child with ASD at 3 to 5 percent, Ozonoff’s work projected that the rate is closer to 15 to 20 percent or four times greater than previously believed.

Discovering autism’s earliest signs

Ozonoff’s team has been pivotal to identifying some of the earliest behavioral signs of autism in very young children.

“Many people think that you’re born with autism,” Ozonoff said during a recent interview, “but we’ve found that the behavioral signs are actually not evident in very early infancy.

Sally Ozonoff © UC Regents"The first phase of our study found that the earliest indicators of autism are seen around 12 months. Some of these signs include failing to respond to your name when called or the unusual use of objects or toys."
— Sally Ozonoff

“The first phase of our study found that the earliest indicators of autism are seen around 12 months. Some of these signs include failing to respond to your name when called or the unusual use of objects or toys. Unfortunately, there are few markers at 6 months of age or earlier that would help us identify which babies are at the highest risk.”

In a report published in 2007 in the Archives of Pediatric & Adolescent Medicine, Ozonoff and her colleagues, including former post-doctoral fellow Aparna Nadig, reported that the failure of a 12-month-old child to orient to someone calling his or her name is highly suggestive of a developmental abnormality. While this failure to respond was observed in 15-20 percent of young siblings of children diagnosed with autism, 100 percent of infants in the comparison group, who had older siblings with typical development, responded when their names were called.

Another study, published in Autism: The International Journal of Research and Practice in 2008, reported that repetitive or stereotyped behaviors, one of the triad of symptoms diagnostic of autism, often are present by 12 months of age in toddlers who are developing autism — much earlier than initially thought.

Seeking the earliest possible clues

The second five-year phase of the study is focused on examining even earlier potential indicators of autism for clues to vulnerability to the disorder.

“So far, we haven’t been able to find behavioral signs of autism at 6-to-9 months of age,” Ozonoff said, “but that doesn’t mean that they don’t exist. We may not have been looking at the right things in our first study.”

“We are now turning our focus to very basic, low-level processes that might help us identify the highest risk infants,” Ozonoff said.

“For example, we think that there may be subtle differences in some very basic processes of vision, attention and speech perception that might help us figure out whether a child is particularly vulnerable and may soon begin to show symptoms of autism, even at this very young age.”

For the first phase of the study, the National Institute of Mental Health (NIMH) provided $1.5 million in funding. The NIMH has increased the study’s fund-ing to $2.25 million for the second five years. During this phase, MIND Institute and UCLA researchers are recruiting a new sample of infant siblings of children with autism, as well as following the original group of participants, who are beginning to enter school.

"In addition to more standard testing for signs of autism, we’ll look at behaviors that aren’t usually associated with autism at this early age," Ozonoff said of the second-phase of the study. "These will include movement and visual processing, how infants track objects with their eyes, and integrate auditory and visual information."

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MIND Institute © UC Regents

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The Infant Sibling Study is part of the Baby Siblings Research Consortium, a voluntary network of more than 15 universities in the United States, Canada and Israel studying infant siblings of children with autism, and working together to examine questions that require large sample sizes. Ozonoff is currently the chair of this large, multi-site group and as such is directing many of the projects undertaken by the consortium. One particularly important undertaking of the consortium is understanding the recurrence risk of autism, that is, how likely a family with one child with autism is to have another child with the condition.

Additional participants needed

The Infant Sibling Study is actively recruiting participants. Anyone with an older child with autism who is either expecting a baby or who already has an infant no older than 9 months can volunteer. To contact study coordinators, please call (916) 703-0297.

The rewards of participation include not only receiving repeated expert diagnostic evaluations and referrals for any developmental concerns that may arise, but also helping to shape new tools to detect autism in infants, tools that can be used in the very near future.

“At least five of the 12 symptoms of autism used in our standard diagnostic manual aren’t applicable to children under 2 years,” Ozonoff said. “We need — and are now developing — new diagnostic tools for young children under 2.”

The ultimate goal is to get children into intervention as early as possible.

“Usually there’s a vague answer when a parent asks how research will help their child,” Ozonoff said, “but this study has immediate applicability and already has begun to help in the diagnosis of infants everywhere.”