Early Predictors of Restricted and Repetitive Behaviors in Toddlers at-Risk for ASD

Background: Developmental theory suggests that RRBs in children with Autism Spectrum Disorder (ASD) may function to occupy and soothe oneself, which may interfere with new experiences and learning (Leekam, Prior, & Uljarevic, 2011). Previous findings also suggest that severity of RRB symptoms might be linked with limited communicative skills.  Specifically, increases in language levels were associated prospectively with decreases in RRBs in 2 to 3-year-olds with ASD (Subramanian and Weismer, 2012). Despite potential clinical and theoretical importance of the relationship between communication skills and RRBs, evidence in this area remains scant. The current study seeks to extend the literature by examining the association between language acquisition and RRBs in the second year of life, a critical developmental period for communication skills and emergence of RRBs.

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.