Executive Functioning and Behavior Problems in Intellectual Disability and Autism Spectrum Disorders

Background:  Aggression and externalizing behavioral problems are frequently reported in the intellectually disabled (ID) population. These challenging behaviors are especially common among individuals with ID who have an additional Autism Spectrum Disorder (ASD) diagnosis. It is proposed that mainly individuals with ASD who are impaired in EF might be prone to display behavioral problems, since EF deficits are related to a need for sameness, lack of impulse control, and difficulty in switching.

Objectives:  The aim of this study is to measure problem behavior in an ID-population with and without ASD-diagnosis and examine the role of EF-components inhibition, updating and shifting in predicting these behavioral problems.

Methods:  Sixty individuals with mild to borderline ID (IQ range 50-85) of which half were diagnosed with ASD, were recruited from three residential care providers in the Netherlands. Counselors completed rating scales concerning the participants’ daily functioning, thereby reporting severity of ASD-symptoms (ratinglist of DSM-IV criteria) and deficits in EF-behavior (BRIEF, BFRS). Additionally, six neuropsychological EF-tasks were administered to measure three different EF-components; inhibition (ANT SSV, ANT ROA), shifting (WCST, CANTAB ID/ED) and updating (Fluency, Digit Span Backwards). Challenging behavior was assessed using counselor based ratings of externalizing and internalizing behavioral problems (ABCL).

Results:  ASD-diagnosis proved to have a poor predictive value for behavioral problems in our sample; no significant difference was found between the ID group with ASD and the ID group without ASD on behavioral problems. The severity of ASD-symptoms did correlate with problem behavior, but this relationship was only significant for internalizing and not for externalizing problem behavior. No significant correlations were found between neuropsychological EF-measures and behavioral problems. In contrast, reported problems in daily EF-behavior were significantly related to both internalizing and externalizing behavioral problems. Strikingly though, these relationships were mainly found in the ID-group without ASD compared to the ID-group with ASD. Posthoc analyses revealed a significant difference in variance of EF-ratings between the two groups, with a lack in variance in the ID group with ASD.

Conclusions:  EF-functioning was found to be more sensitive in predicting behavioral problems than ASD-diagnosis, but only if measured using counselor based EF-ratings and not when using neuropsychological EF-tasks. However, our findings suggest that counselors rate the two ID-groups in different ways; they appear to be less able to view differentiation in EF-behavior of ID-individuals with ASD as compared to individuals diagnosed with solely ID. This finding has implications for future use of EF-rating scales in research and clinical practice.