Efficacy of IMPACT in Infant Siblings of Children With ASD

This two-site randomized controlled trail (RCT) will include a sample of 80 siblings of children with ASD (Sibs-ASD) (11 months, 15 days to 18 months, 15 days) who are stratified on initial cumulative-risk status for communication disorder and then randomly assigned to Ingersoll's Improving Parents As Communication Teachers (ImPACT; Ingersoll \& Dvortcsak, 2010) treatment or to a business-as-usual (BAU) control condition. The following hypotheses will be tested: 1. Compared to the BAU Control, children assigned to the ImPACT group will show (a) more growth on pivotal skills and language level, and (b) a lesser degree of ASD symptomatology and language delay. 2. Pretreatment, cumulative-risk level will statistically interact with (i.e., moderate) treatment assignment to predict children's (a) change in pivotal skills and language, and (b) severity of autism symptoms and language delay. 3. Compared to the BAU Control, parents in ImPACT will have more optimal parenting stress and parenting efficacy, at least in parents with average or below average depressive symptoms prior to treatment (i.e., depressive symptoms will moderate the effect of ImPACT on parental stress and parenting efficacy). 4. The effect that ImPACT has on growth of pivotal skills and language will be mediated by parents' frequency and fidelity of use of ImPACT strategies at immediate post-treatment. 5. The effect of ImPACT on degree of children's language delay and ASD symptomatology at 6 months post-treatment will be mediated by their pivotal skill level at 3 months post-treatment.