Relationships Between Restricted and Repetitive Behaviours and Adaptive Skill Development Over 4-5 Years in Children with ASD

Background: A diagnosis of autism spectrum disorder (ASD) requires the presence of restricted and repetitive behaviors (RRBs); however, relatively few studies to date have examined the relationship between this broad category of behaviors and changes in other developmental variables over time. Examination of such relationships may aid in our understanding of the impact of ASD symptomatology on skill acquisition.

Objectives: To examine the relationship between early RRBs and the development of adaptive behavior skills in a cohort of young children with autism who were followed over 4-5 years.

Methods: Longitudinal data were collected for 69 children with ASD (84% males, mean CA=50 months) prior to intervention (T1) and 6 (T2), 12 (T3), 24, 32, and 53 months later, using subscales from the Vineland Adaptive Behavior Scales (VABS). The RRB variable used at T1, T2, and T3 was constructed using cross-test items endorsed by an expert jury. The coefficient alpha for the RRB variable was 0.77, indicating that it was internally consistent with little measurement error. After controlling for chronological age, nonverbal IQ, and autism severity, T1 to T3 RRBs and changes in RRBs over the first 6 and 12 months of intervention were examined as predictors of the developmental trajectories of VABS communication, social, and daily living skills using SAS Proc Mixed analyses.

Results: Children's RRB scores at both T2 (β = -0.033, t(69) = -2.75, p = 0.006) and T3 (β = -0.026, t(69) = -2.42, p = 0.016) predicted the development of VABS daily living skills over 4-5 years. In addition, changes in children's RRB scores over the first 6 months of intervention (T2 – T1) predicted the slope of daily living skills over 4-5 years (β = -0.029, t(69) = -2.02, p = 0.044). RRBs did not predict the development of either adaptive communication or social skills over time. Overall, children who had higher RRB scores at T2 or T3 had less of an increase in the slope of daily living skills over 4-5 years. In addition, children whose RRBs improved over the first 6 months of intervention had more of an increase in the slope of daily living skills over time.

Conclusions: Past research has found some evidence for a general relationship between RRBs and other variables (e.g., Gabriels, Cuccaro, Hill, Ivers, & Goldson, 2005; Honey, McConachie, Randle, Shearer, and LeCouteur, 2008). This is the first study to find a predictive relationship between early RRBs and the development of daily living skills over a long time period (i.e., 4-5 years). In this study, RRBs included both repetitive stereotypic gross and fine motor behaviors such as hand flapping, rocking, and humming; and insistence on sameness behaviors such as lining up objects and demanding that routines always occur in the same way. It appears that high levels of RRBs negatively affect the acquisition of daily living skills, perhaps because, like RRBs, they involve both gross and fine motor skills and usually occur in a predictable sequence (e.g., hand washing, dressing).