Early Predictors of Restricted and Repetitive Behaviors in Toddlers at-Risk for ASD
Objectives: Examine the association between early language skills and RRBs in younger siblings of children diagnosed with ASD. We hypothesize that RRBs and dynamic language acquisition will predict later levels of RRBs in high-risk siblings.
Methods: Participants were 98 high-risk infants followed prospectively at 12, 18, 24, and 36 months. The sample consisted of toddlers with ASD (n = 16), developmental delays (n = 36), and no clinical features (n= 46). Comprehensive evaluations were conducted at each time point. Language skills were assessed with the MSEL (e.g., age equivalent (AE) scores). RRBs were assessed through clinical observations with the ADOS (e.g., RRB total scores). Rate of skill acquisition was calculated by determining the change in AE scores between visits divided by the time that passed between visits (Klintwall, Macari, Eikeseth, & Chawarska, 2015). The hypothesis was evaluated using multiple regression analysis with RRB at 24 months as the predicted variable, and EL rate acquisition and RRB levels at 12 and 18 months as predictors. Analyses were conducted on the combined HR sample to evaluate associations between RRB and language development across the spectrum of risk.
Results: The dependent variable for the high-risk cohort was a measure of clinically-observed RRBs at 24 months (M=1.21; SD = 1.36; Min = 0; Max = 7). Mean RRBs at 12 and 18 months were .96 and 1.29, respectively. Rates of EL growth between 12 and 18 months and 18 and 24 months were 1.05 and 1.59, respectively. Multivariate regression analysis revealed the model significantly accounted for 26% of the variance in 24-month RRB scores (F(9, 84) = 4.612, p = .000; adjusted R2 = .259), with 12-month RRB scores (β = .247, p = .034) and 18-24 month EL Acquisition Rate scores (β= -.423, p = .007) making significant contributions.
Conclusions: The results suggest that higher level of RRBs at 12 months and lower rates of language acquisition between 18 and 24 months predict higher levels of RRBs at 24 months in high-risk siblings. These results highlight the role of expressive language development in the emergence of RRBs in high-risk toddlers and underscore the importance of intervention targeting language development in high-risk toddlers between 18 and 24 months of age.