About 20% of children with an older sibling who has autism also will be diagnosed with the disorder, according to a new study.
The findings are consistent with a 2011 study conducted by many of the same researchers. They emphasized the need to closely monitor siblings, especially those with certain characteristics.
Researchers analyzed data on 1,605 infants whose older sibling has autism and who were followed to age 3 years. Both the current and the 2011 studies looked at children in the Baby Siblings Research Consortium and used the same procedures so the estimates could be compared reliably.
The team found 20.2% of the younger siblings developed autism, statistically about the same as the finding of 18.7% in 2011, according to “Familial Recurrence of Autism: Updates From the Baby Siblings Research Consortium” (Ozonoff S, et al. Pediatrics. July 16, 2024).
About 1 in 36 children has autism, and rates have been increasing. Researchers said their study indicates the rate increase and other changes since 2011 like greater identification of females and cognitively able children have not impacted rates of family recurrence.
The biggest risk factors for family recurrence they found were the younger sibling being male or having multiple older siblings with autism. In addition, younger siblings of females with autism were more likely to be diagnosed with the disorder than younger siblings of males with autism.
The rate of sibling recurrence was about 17.8% of white families compared to 25% of families of other races. Higher levels of maternal education were associated with lower levels of recurrence. Maternal or paternal age did not seem to play a role.
“Collectively, these findings indicate the need for further research examining social, economic, and environmental contributions to health care disparities generally and increased recurrence in more vulnerable families specifically,” authors wrote.
They also said the findings “emphasize the need for close developmental surveillance of infant siblings during well-child visits to ensure timely referral for diagnostic evaluations or early intervention services.”
The AAP recommends developmental screenings at 9, 18 and 30 months and screening for autism at ages 18 and 24 months.
Resources
- AAP clinical report Identification, Evaluation, and Management of Children with Autism Spectrum Disorder
- AAP autism resources
- AAP toolkit on caring for children with autism
- Information for parents from healthychildren.org on early signs of autism
- CDC program: Learn the Signs. Act Early.
