Approximately 20 percent of younger siblings of children with Autism Spectrum Disorder (ASD) will develop the disorder by age three. Of these, 57 percent may show symptoms at 18 months, according to a new study by the Yale School of Medicine.
“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,” said lead author Katarzyna Chawarska, Ph.D., associate professor in the Yale Child Study Center and the Department of Pediatrics at Yale 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.”
The study is the first large, multi-site study designed to identify specific social-communicative behaviors that distinguish infants with ASD from their typically and atypically developing high-risk peers as early as 18 months of age. The findings are published in the Journal of the American Academy of Child & Adolescent Psychiatry.
For the study, researchers gathered data from eight sites participating in the Autism Speaks Baby Siblings Research Consortium. The team analyzed the social, communicative, and repetitive behaviors in 719 infants at 18 months old.
The researchers looked for patterns that might predict a later diagnosis of ASD. They then followed up the children at age three.
“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,” said Chawarska.
In about 50 percent of the siblings, a combination of poor eye contact and lack of communicative gestures or imaginative play was most strongly tied to a later diagnosis of ASD.
In a small percentage of children later diagnosed with ASD, eye contact was relatively normal, but they began to show early signs of repetitive behaviors with 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 said.
“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