Hyperactivity in boys with attention-deficit/hyperactivity disorder: The influence of underlying visuospatial working memory and self-control processes

- Boys with ADHD exhibited greater motor activity across tasks.
- The activity of both groups was greatest during executive function tasks.
- VS-WM accounted for the most variability in activity across tasks.
- ADHD-related hyperactivity appears to be predominantly associated with deficient WM.

Changes in motor activity were examined across control and executive function (EF) tasks that differ with regard to demands placed on visuospatial working memory (VS-WM) and self-control processes. Motor activity was measured via actigraphy in 8- to 12-year-old boys with (n = 15) and without (n = 17) attention-deficit/hyperactivity disorder (ADHD) during the completion of VS-WM, self-control, and control tasks. Results indicated that boys with ADHD, relative to typically developing boys, exhibited greater motor activity across tasks, and both groups' activity was greater during EF tasks relative to control tasks. Lastly, VS-WM performance, relative to self-control performance, accounted for significantly more variance in activity across both VS-WM and self-control tasks. Collectively, findings suggest that ADHD-related hyperactivity is positively related to increased cognitive demands and appears to be better explained by deficient VS-WM rather than insufficient self-control.