Predicting language and social outcomes at age 5 of younger siblings of children with autism spectrum disorders
This paper examines the relation between early joint attention and later language and social outcomes observed in younger siblings of children with autism spectrum disorder (Sibs-ASD) as compared with younger siblings of typically developing children (Sibs-TD). Initiating joint attention (IJA) and responding to joint attention (RJA) were assessed over 4 measurement periods, each 4 to 6 months apart, between the ages of 12 and 34 months. Follow-up evaluations of language and social competence were conducted at 5 years of age. Both initial levels of joint attention and growth of joint attention were used as potential predictors of outcome. Results revealed a relation between initial (i.e., at a mean age of 15 months) IJA and RJA and age 5 language and social outcomes, as well as a relation between growth in RJA and later social outcomes. Contrary to hypotheses, no group differences in these predictive patterns were observed. At age 5, the performance of Sibs-ASD and Sibs-TD on measures of language and social skills were comparable. The only significant group difference was that parents of Sibs-ASD reported that their children exhibited greater autism-related social difficulties related to autism than relative to Sibs-TD. Overall, findings support associations between early joint attention and later language and social outcomes in both Sibs-TD and Sibs-ASD, extending the importance of joint attention as a predictor of later language and social outcome to Sibs-ASD. Findings also indicate that, despite the increased risk for a broad range of atypical outcomes in Sibs-ASD, this sample exhibited outcomes similar to those of Sibs-TD (whose genetic vulnerability is considerably lower), suggesting positive outcomes for this high-risk group of children. The present findings represent an important contribution to our understanding of younger siblings of children with ASD, their developmental trajectory, and how early concerns translate into later outcomes.