Relationship Between Executive Functioning, Autistic Symptomatology, and Adaptive Behavior

Background: Deficits in adaptive behavior have been widely reported in individuals with ASD. Executive functioning (EF) deficits are also common in these individuals. The research on the relationship between adaptive behavior and EF is more limited. There is also little research on the relationship between EF and autistic symptomatology. Gilotty et al. (2002) found that deficits in metacognitive skills as measured by the Behavior Rating Inventory of Executive Function (BRIEF) were important contributors to adaptive functioning impairments, and Liss et al. (2001) found significant correlations between adaptive skills and perseverative errors on the WCST and performance on the WISC-R Mazes, but the relationships were mediated by Verbal IQ. South et al. (2007) examined the relationship between repetitive behaviors and flexibility and found significant correlations between WCST perseverations and repetitive behaviors scores on the ADOS and ADI-R.

Objectives: The purpose of the current study is to further evaluate the relationship between executive functioning skills, as measured by parent-report data from the Behavior Rating Inventory of Executive Function (BRIEF) and adaptive behavior, as measured by the Vineland Adaptive Behavior Scales, Second Edition (VABS-II), using a large sample of school-aged children with ASD. A secondary purpose of the study is to investigate the relationship between autistic symptomatology, based on ADOS calibrated severity scores, and EF skills.

Methods: The sample included 73 children: 31 from a clinical sample and 42 from a longitudinal study of ASD. Mean age was 8.9 years (s.d. 2.1; range 6-16). Level of cognitive functioning was assessed using the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV) or the Differential Abilities Scale, Second Edition (DAS-II). For the children who received the WISC-IV, the mean IQ score was 96.0 (s.d. 18.9; range 68-149). For the children who received the DAS-II, mean IQ score was 92.2 (s.d. 17.3; range 53-134). All children received the ADOS and were characterized by a team of experienced clinicians.

Results: Overall cognitive ability was not correlated with EF, but the Working Memory and Processing Speed domains from the WISC-IV were negatively correlated with EF impairment. There were no significant relationships between EF behaviors and autistic symptom severity, as measured by the ADOS calibrated severity score. EF behaviors were significantly positively correlated with adaptive functioning, particularly adaptive socialization, daily living, and expressive language skills.

Conclusions: The severity of autistic symptoms is not associated with severity of EF behavioral impairments. However, level of adaptive functioning is associated with EF behaviors. Thus, whereas EF impairments are not related to the social disability in ASD, they are significantly related to level of social ability. The direction of the relationship cannot be determined from this study, but it is reasonable to hypothesize that EF behaviors impact adaptive functioning but also that areas of adaptive functioning (e.g., expressive language skills) may impact EF behaviors, such as regulatory control and problem solving. The clinical implications of these findings include the need to address EF behaviors when treating children with ASD.