Is There a Functional Relation Between Set Shifting and Hyperactivity in Children with Attention-Deficit/Hyperactivity Disorder (ADHD)?

Objective: Replicated evidence indicates that children with attention-deficit/hyperactivity disorder (ADHD) show disproportionate increases in hyperactivity/physical movement when their underdeveloped executive functions are taxed. However, our understanding of hyperactivity's relation with set shifting is limited, which is surprising given set shifting's importance as the third core executive function alongside working memory and inhibition. The aim of this study was to experimentally examine the effect of imposing set shifting and inhibition demands on objectively measured activity level in children with and without ADHD.

Method: The current study used a validated experimental manipulation to differentially evoke set shifting, inhibition, and general cognitive demands in a carefully phenotyped sample of children aged 8-13 years with ADHD (n = 43) and without ADHD (n = 34). Activity level was sampled during each task using multiple, high-precision actigraphs; total hyperactivity scores (THS) were calculated.

Results: Results of the 2 × 5 Bayesian ANOVA for hyperactivity revealed strong support for a main effect of task (BF10 = 1.79 × 1018, p < .001, ω2 = .20), such that children upregulated their physical movement in response to general cognitive demands and set shifting demands specifically, but not in response to increased inhibition demands. Importantly, however, this manipulation did not disproportionally increase hyperactivity in ADHD as demonstrated by significant evidence against the task × group interaction (BF01 = 18.21, p = .48, ω2 = .002).

Conclusions: Inhibition demands do not cause children to upregulate their physical activity. Set shifting produces reliable increases in children's physical movement/hyperactivity over and above the effects of general cognitive demands but cannot specifically explain hyperactivity in children with ADHD.