Beyond the toddler years: A meta-analysis of communicative abilities in siblings of children with autism spectrum disorder.

Communication is a core challenge for individuals on the autism spectrum, and many autistic individuals experience challenges with language. Prospective studies of younger siblings of children with autism show that siblings not only have an increased likelihood of developing autism themselves, but that even siblings without an autism spectrum diagnosis are more likely to have a language delay as toddlers than their peers without familial history of autism (Marrus et al., 2018). While there is substantial variability in the communicative abilities of siblings of children with autism in toddlerhood, it is not clear how these differences translate beyond the first 3 years of life. The present study used meta-analysis to evaluate a wide range of literature and determine whether siblings of children with autism (Sibs-A) over 48 months of age differ from comparison groups in their language and communication abilities. A total of 26 studies describing 22 cohorts were included. Over 2,000 Sibs-A were compared with neurotypical individuals without familial history of autism or siblings of individuals with another neurodevelopmental disability. Meta-analysis revealed a small but significant effect such that Sibs-A performed lower than comparison peers in overall language and communication. Effects were strongest for expressive language and linguistic processing speed, and there were substantially larger differences for experimenter-administered measures than for parent-report, though findings must be considered in the context of other study characteristics. Suggestions based on this meta-analytic review are provided to guide future research in understanding individual differences in the communicative development and outcomes of Sibs-A. (PsycInfo Database Record (c) 2021 APA, all rights reserved).