Parent utilization of ImPACT intervention strategies is a mediator of proximal then distal social communication outcomes in younger siblings of children with ASD.

LAY ABSTRACT: Later born siblings of children with autism spectrum disorders (ASD) are at elevated risk for language delay or ASD. One way to manage this risk may be for parents to use techniques taught in Improving Parents as Communication Teachers (ImPACT) with the younger siblings during the period in which language delay and ASD may be too subtle to be diagnosed. ImPACT targets children's play, imitation, and communication skills. Improvement in these skills may reduce the severity of language delays and social communication deficits associated with ASD. In this study, 97 younger siblings of children with ASD and their primary parents were randomly assigned to ImPACT or a control group. We measured whether parents used ImPACT teaching strategies and whether children used the skills that ImPACT targets. We also measured children's later language ability and social communication skills. The results confirmed our predictions that parents' use of ImPACT strategies improves language ability by improving children's motor imitation and communication skills. Use of ImPACT also had a positive effect on children's language delay and ASD symptoms, supporting the clinical value of the findings. The study's methodological strengths make this one of the most rigorous tests of ImPACT and supports one way to manage the risk of language delay and ASD in younger siblings of children with ASD.