New research highlights sibling connection for children with ASD

Children who have an older sibling with autism spectrum disorder (ASD) are at greater risk of developmental vulnerabilities if they also have other relatives with neurodevelopmental or psychiatric conditions, according to a new study from the Yale Child Study Center.

The siblings of children with ASD, researchers found, had an increase in the severity of social and communication difficulties — which are common in ASD — if they had relatives with conditions such as schizophrenia or anxiety. 

ASD is a neurodevelopmental condition characterized by social and communication impairments as well as sensory sensitivities, repetitive behaviors, and stereotyped interests. Past research has shown that younger siblings of children with ASD exhibit a wide range of developmental concerns across social, cognitive, language, and adaptive functioning.

Symptoms in some siblings are severe, span across multiple domains, and result in a diagnosis of ASD, while they may be milder or present only in some developmental areas for others. Many siblings progress to develop typically.

Family histories of anxiety and intellectual disability were also associated with lower verbal and nonverbal skills and with less-developed adaptive skills in siblings participating in the study, according to the research published in the journal Autism Research.

These findings can be useful in supporting those who work with children in a professional context to support children living with ASD and their families.

“We are always on the lookout for information to help us monitor and support development of infants with known risk factors for developmental disorders,” senior author Professor Katarzyna Chawarska said. 

“Considering family history of these disorders may improve efforts to predict long-term outcomes in younger siblings of children with autism and inform about factors contributing to variable phenotypic outcomes in this cohort.”

To reach their findings the research team collected family history information from parents of 229 younger siblings of children with autism between March 2006 and May 2022, and had the  siblings participate in a comprehensive evaluation of social, cognitive, language, and adaptive skills.

The researchers investigated whether family history of neurodevelopmental and psychiatric conditions related to developmental outcomes of younger siblings of children with ASD, controlling for variables such as the child’s birth year, age, sex assigned at birth, and family demographics.

“It is not clear what drives such heterogeneity of outcomes in younger siblings of children with autism,” Professor Chawarska said. “Identifying factors linked with variable outcomes is essential for improving understanding of their underlying biology and for early identification of the most vulnerable siblings.”

As in prior studies, the researchers found an elevated prevalence of neurodevelopmental and psychiatric disorders in the first-, second-, and third-degree relatives of children with ASD.

According to the Professor, the conditions most commonly present in relatives included anxiety disorders, schizophrenia, bipolar disorder, depression, attention-deficit/hyperactivity disorder, speech delays, and intellectual disability.

“Future studies will be necessary to disambiguate the mechanistic underpinnings of the observed associations between family history and developmental outcomes,” she noted.

Access the findings in full here.