About 20 percent of children who have older siblings with autism also develop the disorder. Of those children, 57 percent show symptoms as early as 18 months.
The findings stress the need for early and repeated screening in the first three years of life so that, if necessary, intervention can begin as soon as possible.
A large-scale study has identified specific social-communicative behaviors that distinguish infants with autism spectrum disorder (ASD) from their typically and atypically developing high-risk peers as early as 18 months of age.
“While the majority of siblings of children with ASD will not develop the condition themselves, for those who do, one of the key priorities is finding more effective ways of identifying and treating them as early as possible,” says Katarzyna Chawarska, associate professor in the Child Study Center and the Department of Pediatrics at Yale University School of Medicine.
“Our study reinforces the need for repeated diagnostic screening in the first three years of life to identify individual cases of ASD as soon as behavioral symptoms are apparent.”
Patterns of behavior
For the study, published in the Journal of the American Academy of Child & Adolescent Psychiatry, researchers pooled data from eight sites participating in the Autism Speaks Baby Siblings Research Consortium. The team closely examined social, communicative, and repetitive behaviors in 719 infants when they were 18 months old.
The team looked for patterns that might predict a later diagnosis of ASD. They then followed up when the participants were age 3.
“Our research suggests that approximately half of the siblings who are later diagnosed with ASD display signs suggestive of ASD at 18 months, and in those who appeared asymptomatic at 18 months, symptoms appeared between 18 and 36 months,” Chawarska says.
What was most interesting to the research team was that different patterns of behaviors at 18 months may be predictive of ASD later on. In about 50 percent of siblings, a combination of poor eye contact and lack of communicative gestures or imaginative play is most strongly associated with later ASD diagnosis.
In a small percentage of those later diagnosed with ASD, eye contact may be relatively normal, but they begin to display early signs of repetitive behaviors and have limited non-verbal communication skills.
“So not only do the behavioral symptoms appear at different ages, but different combinations of early symptoms may predict the diagnostic outcome,” Chawarska says.
“Linking these developmental dynamics with underlying neurobiology may advance our understanding of causes of ASD and further efforts to personalize treatment for ASD by tailoring it to specific clinical profiles and their developmental dynamics.”
Source: Yale University
