Do Restricted and Repetitive Behaviors during Early Childhood Predict School-Age Executive Functioning Among Children with Autism Spectrum Disorders?

Background: Restricted and Repetitive Behaviors (RRBs) are core features of Autism Spectrum Disorders (ASDs) and include motor stereotypies, preoccupation with parts of objects, restricted interests, insistence on sameness, and sensory interests. One theory proposed to explain the purpose of RRBs points to executive dysfunction and argues that RRBs result from a tendency to perseverate, as well as from deficits in planning, self-monitoring, inhibition of ongoing behaviors, and initiation of new behavior (Russell, 1997). However, because RRBs emerge earlier in development than functions usually grouped under executive functioning (EF), it is important to consider the alternate causation, namely, the effect that RRBs may have on the development of EF. Studies examining the relationship between EF and RRBs are limited and have not examined the impact that early RRBs have on the development of EF (see Leekham et al., 2011).

Objectives: The current study used a longitudinal design to examine the extent to which RRBs at two points in early childhood predict school-aged executive functioning.

Methods:   Participants included 40 children diagnosed with ASD at age 1-2 years and again at age 3-5 years. Participants were recruited from a study examining the effectiveness of the Modified Checklist for Autism in Toddler (M-CHAT), a screening instrument designed to identify children at risk for developing ASDs. RRBs were examined at age 1-2 years (M=2.2, SD=0.3; M(Mullen ELC)=58.7, SD=8.5) and 3-5 years (M=4.3 years, SD=0.4; M(Mullen ELC)=63.1, SD=19.5), and were assessed using both direct observation and parent report. RRBs were used to predict EF at age 8-10 years (M=9.9, SD=0.8; M(VIQ)=70.8, SD=31.5; M(NVIQ)=81.4, SD=27.4). EF was examined using the Behavior Rating Inventory of Executive Function (BRIEF), a parent report questionnaire designed to assess EF in daily settings.

Results:   Linear regression indicated that RRBs observed at age 1-2 are significant predictors of school-age EF as measured by the Global Executive Composite (GEC) of the BRIEF (F(6, 25)=2.52, p<.05, Adjusted R²=.23). Specifically, RRBs at age 1-2 significantly predicted difficulties with cognitive flexibility and initiation of new behaviors (Shift: F(6, 25)=2.51, p<.05, Adjusted R²=.23; Initiation: F(6, 25)=2.75, p<.05, Adjusted R²=.25). According to these models, increased self injurious behaviors predicted greater difficulty with cognitive flexibility (beta=0.47, p<.05). In contrast, reduced repetitive motor mannerisms predicted more difficulty with initiation of new behaviors (beta=–0.36, p<.05). When RRBs were assessed at age 3-5 years, they did not predict the GEC (F(6, 25)=1.59, p=.19, Adjusted R²=.11), but RRBs were significant in predicting reduced cognitive flexibility (F(6, 24)=3.01, p<.05, Adjusted R²=.29). At age 3-5, more severe adherence to rituals or routines (beta=0.42, p<.05) and greater preoccupations with parts of objects (beta=0.41, p<.05) predicted increased difficulty with cognitive flexibility.

Conclusions:   This study found a predictive relationship between RRBs in early childhood and school-aged EF. Because RRBs emerge earlier in development than classically defined EF, these findings raise two possibilities: first, that RRBs may impact neurocognitive development and the development of EF, and second, that precursors of EF, such as early manifesting inflexibility and perseveration, impact the development of both RRB’s and later developing EF.