Adaptive Behavior in Preschoolers with Autism Spectrum Disorder: The Role of Executive Function

Background: Adaptive behavior, the ability to function independently, is a well-measured concept that relates closely to functional outcomes in individuals with autism spectrum disorder (ASD). Even in the preschool years, children with ASD demonstrate poorer adaptive behavior than those with Down syndrome, a group with impaired cognitive ability, suggesting that cognitive ability alone does not explain the discrepancy in these skills. Research also suggests that adaptive behavior impairment increases with age, warranting research on which factors explain adaptive behavior, as well as its change over time. Some studies have demonstrated the importance of executive function skills, such as shifting and organization, in predicting adaptive behavior in individuals with ASD. However, this research has focused on school-age youth with average to above-average intelligence. Less work has extended into younger samples or those with a broader range of cognitive abilities, so it is not known whether the same skills are implicated across the ASD population and across development.

Objectives: To examine the association between executive function and adaptive behavior in preschoolers with ASD.

Methods: Ninety-one preschoolers with ASD (mean age=52.1 months; 81% male) from two sites were included in this analysis. At one site, teacher report on the Behavior Rating Inventory of Executive Function – Preschool (BRIEF-P) and the Adaptive Behavior Assessment System-II (ABAS-II) were used to assess executive function and adaptive behavior respectively. The other site relied on caregiver report on both the BRIEF-P and the Vineland Adaptive Behavior Scales, Second Edition (Vineland-II). We standardized measures of adaptive behavior by focusing only on adaptive practical and socialization skills. “Adaptive practical skills” were either Vineland-II Daily Living Skills Standard Score or ABAS-II Practical Composite Standard Score. Depending on site, cognitive or developmental functioning level (hereinafter, “nonverbal IQ”) was measured by either a nonverbal subtest of the Differential Ability Scales-2 or Wechsler Preschool and Primary Scale of Intelligence-III, or Visual Reception on the Mullen Early Learning Scales. Stepwise regressions were conducted for each adaptive behavior domain to determine the unique variance contributed by the BRIEF-P scales, above and beyond nonverbal IQ (Table 1). Site was also entered as a covariate of no interest to minimize confounding effects from site differences, including rater and measure differences.

Results: For adaptive practical skills, nonverbal IQ and site accounted for 28.4% of variance. The BRIEF-P scales explained 8.0% of variance in practical skills and the model comparison was marginally significant; Plan/Organize scale was statistically significant. For adaptive socialization skills, the covariates predicted 13.5% of variance, but only nonverbal IQ was significant. The BRIEF-P scales explained an additional 12.0% of variance in socialization skills, with the Shift scale reaching statistical significance.

Conclusions: These results show that specific executive function skills play an important role in explaining variance in different aspects of adaptive behavior in early development, extending prior literature into preschoolers with ASD. Future research should replicate these findings with longitudinal designs and performance-based measures to sharpen our understanding of executive function in preschoolers with ASD, which may provide insight for adapting interventions to improve functional outcomes.