This study examines receptive-expressive language, gross-fine motor skills, and IQ abilities in 78 children, 43 children with an older sibling with autism spectrum disorder (Sibs-ASD) and 35 children with an older sibling with typical development, ranging from 4 to 11 years of age. Depending on age, both groups were divided in preschool and school groups. The results show that more than 76% of Sibs-ASD performed at least one language and/or motor skill under 25th percentile. Significant differences were described at preschool stage in three aspects: grammatical comprehension, ball skills, and global motor skills. At school age, significant differences were found in two aspects: expressive language, and ball skills. Some differences seem to decrease over time; meanwhile others seem to increase; and others remain stable. Thus, it seems that vulnerability continues in unaffected Sibs-ASD and suggest that this population may benefit from continued screening and monitoring into the preschool and school-age stages.
Keywords: autism spectrum disorder; language skills; motor skills; siblings.