Inhibition in developmental disorders: A comparison of inhibition profiles between children with autism spectrum disorder, attention-deficit/hyperactivity disorder, and comorbid symptom presentation

Abstract

Many children with autism spectrum disorder (ASD) also have symptoms of attention-deficit hyperactivity disorder (ADHD). Children with ASD and ADHD often experience difficulties with inhibition. This study had the goal of understanding inhibition in children with ASD, ADHD, ASD + ADHD, and children who are typically developing (TD) using tasks that measured several aspects of inhibition. Results indicate that children with ASD + ADHD had greater difficulty inhibiting behavioral responses than TD children. Children with ASD + ADHD also differed from children with ASD and with ADHD in their inhibition of distracting information and strategic slowing of response speed. The four groups did not differ in their avoidance of potential losses. Children with ASD + ADHD exhibit a unique profile of inhibition challenges suggesting they may benefit from targeted intervention matched to their abilities.

Keywords: attention-deficit/hyperactivity disorder; autism spectrum disorder; cognition (attention, learning, memory); executive function; inhibition; interventions—psychosocial/behavioral; psychological theories of autism.

Figure 1.

Group sample sizes after filtering for eligibility and inclusion criteria. Notes: ASD = autism spectrum disorder; ADHD = attention-deficit/hyperactivity disorder; TD = typical development; DQ = disqualified from study; ADOS-2 = Autism Diagnostic Observation Study, Second Edition; ADI-R = Autism Diagnostic Interview-Revised; WASI-2 = Wechsler Abbreviated Scale of Intelligence, Second Edition; CBCL = Child Behavior Checklist; SRS-2 = Social Responsiveness Scale, Second Edition; N/A = not applicable

Figure 2.

Group performance on tasks measuring distinct types of inhibition, namely (A) interference suppression measured by the difference in cRT between congruent and incongruent trials on the Stroop Task, (B) reactive inhibition measured by SSRT (the time required to inhibit a go response when a stop signal was presented) during the Stop-Change Task, (C) proactive inhibition measured by the difference in cRT to go trials during practice and test blocks of the Stop-Change Task (where the number of trials in the practice and test blocks were comparable), and (D) motivational inhibition measured by the number of selections from doors with high frequency losses during the final 40 trials of the 100 trial Hungry Donkey Task. Notes: Z-scores were computed relative to the TD group; means are adjusted for IQ; error bars represent standard error; TD = typical development; ASD = autism spectrum disorder; ADHD = attention-deficit/hyperactivity disorder; cRT = correct response time; SSRT = stop signal reaction time; ms = milliseconds ^† p ≤ 0.08; * p < 0.05; ** p < 0.01