Executive Function in Preschoolers with ASD: Evaluation of a Test Battery with Minimal Verbal Demands

Background: Executive Function (EF) refers to a set of cognitive processes that regulate impulses and emotions and channel them into socially appropriate, goal-directed behavior. Core EF processes include working memory, inhibition, and shifting (Diamond, 2013). Impaired EF is linked to a number of poor outcomes in school-age youth and adults with autism spectrum disorder (ASD), including lower adaptive behaviors, more repetitive behaviors, and poorer social skills (Yerys et al, 2009; Pellicano, 2012). Less is known about EF in the preschool years, as few standardized measures have been validated in children of this age with developmental delays.

Objectives: This study evaluates the feasibility and reliability of an EF battery that places no expressive verbal demands and minimizes the need for receptive verbal skills in preschoolers with ASD.

Methods: A total of 56 preschoolers with ASD (mean age=51.6 months; 80% male) completed a 20-minute EF battery that included putative measures of inhibition (Balance Beam Task, Tongue Task, and NEPSY-II Statue Subtest), working memory (Leiter-3 Memory Subtests), and shifting (Spatial Reversal Task). To evaluate feasibility, completion rates were calculated for each measure, as the percentage of children who were willing and able to complete the task and demonstrated understanding of task instructions. The role of developmental functioning (according to the Mullen Visual Reception Age Equivalent (VRAE)) on task completion and performance was also evaluated. Task order was counterbalanced to account for possible order and fatigue effects in the battery. The battery was re-administered to 16 children within two weeks from the initial administration, and intraclass correlations (ICC) were calculated to measure test-retest reliability.

Results: Regarding feasibility, only the Spatial Reversal Task had a successful completion rate greater than 80% for the entire sample (i.e. <20% were unable to complete the task or scored a zero). However, completion rates were at least 80% for Tongue Task when VRAE from the Mullen was at least 19 months (n=20) and for Leiter-3 Forward Memory Subtest when VRAE was at least 14 months (n=38). The Balance Beam and Statue tasks demonstrated very poor feasibility in this sample. For the 16 children who were retested, completers versus non-completers were consistent across time for Spatial Reversal, Tongue Task, and Forward Memory (ICC>.75). Performance reliability was also acceptable for total correct responses on Spatial Reversal (ICC=.73) and excellent for the Tongue Task and Forward Memory (ICC>.90).

Conclusions: EF is an important aspect of cognition to accurately measure in ASD because of its strong relationship with several important outcomes in older children and adults with ASD. This study provides initial evidence for the feasibility and reliability of a preschool EF assessment that minimizes verbal demands, along with potential developmental age guidelines for administration. This study suggests that a valid preschool EF battery that is sensitive to delayed cognitive development is attainable.