Siblings of Autistic Children May Also Display Language Difficulties


Autism Spectrum Disorder is a condition that affects the brain’s normal development of social and communication skills. As many as one in 110 children have been diagnosed with some form of the disease. Although one of the causes is thought to be genetic, many autistic children have normally developing siblings, but a new study has found that those children may also display subtler problems with language and speech.

Brothers and Sisters of Autistic Children More Likely to Be Affected Themselves

Study author Dr. John Constantino, professor of psychiatry and pediatrics at the Washington University School of Medicine, and colleagues used data from the Interactive Autism Network, a database of more than 35,000 participants. The group narrowed the focus of the study to a group of 1,235 families, including about 3,000 children, who completed a Social Responsiveness Scale questionnaire on each of the children living in their home between the ages of 4 and 18 years old.

The researchers found that almost 11 percent of families had more than one child with an autism diagnosis and an additional 20 percent who had children unaffected by the disorder, but who did have language delays. Among those with language difficulties, about half “exhibited autistic qualities of speech.” Girls were more likely to have these subtle traits of potential autism than boys.

Read: Toddlers with Autism Pronounce Words Differently


Because parents completed the questionnaires subjectively, this study wasn't able to determine if the siblings were experiencing a mild form of autism, or if these were isolated language delays.

"Smaller studies have reported that in families with children with autism, many children who don't have an autism diagnosis have had a language delay," said Dr. Constantino. "When we looked at this huge sample, we saw the same thing -- about 20 percent of children presumed to be non-autistic had language delays and autistic qualities in their speech. In the general population, the prevalence of these traits is only about 7 percent," he said.

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Because children who have a brother or sister diagnosed with autism are about 22 times more likely to be affected themselves, Dr. Constantino suggests that families with one autistic child have their other children screened, particularly if they show evidence of language delays.

Results of the study were published in the November issue of the American Journal of Psychiatry.