Children with autism spectrum disorder (ASD) show significant linguistic and motor impairments compared to children with typical development (TD). Findings from studies of siblings of children with ASD show similarities to conclusions from studies of children with ASD. The current meta-analysis reviewed studies reporting linguistic and/or motor skills in siblings of children with ASD compared to siblings of children with TD. Thirty-four studies published between 1994 and 2016 met all inclusion criteria. We compared three different age groups (12 months or younger, 13 to 24 months, and 25 to 36 months). At 12 months, compared to siblings of children with TD, siblings of children with ASD had worse receptive language (d = -.43, 95% CI [-.53, -.33]) and expressive language skills (d = -.40, 95% CI [-.57, -.23]), and these effects were sustained at 24 and 36 months. Similar, albeit smaller differences in fine motor skills were detected at 12 months (d = -.22, 95% CI [-.39, -.04]), and these differences were larger at 36 months (d = -.36, 95% CI [-.54, -.17]). There were differences in gross motor skills at 12 months (d = -.22, 95% CI [-.40, -.04]), but only a few studies were available at later ages. Compared to siblings of children with TD, infants who have siblings with ASD have worse linguistic and motor skills. These differences are detectable as early as when infants are 12 months old and seem to be sustained until they are 3 years old. Differences in language skills are larger than those in motor skills, especially during the first year. Autism Res 2017, 10: 1737-1750. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.
Lay summary: We reviewed studies reporting linguistic and/or motor skills in siblings of children with autism spectrum disorder (ASD) compared to those in siblings of children with typical development. The results showed that as a group, those infants who have siblings with ASD have less advanced linguistic and motor skills. These differences are detectable when infants are 12 months old and seem to be sustained until they are 3 years old. Differences in language skills are larger than those in motor skills.
Keywords: autism; high risk; language; meta-analysis; motor; siblings.
© 2017 International Society for Autism Research, Wiley Periodicals, Inc.