Postural control variability in medicated and unmedicated children with ADHD

Objectives and methods: Postural instability is common among children with ADHD. Research on the effects of psychostimulant medication on postural control outcomes in ADHD is limited, and findings are mixed. By assessing static and dynamic balance, this multi-level approach attempts to offer a more comprehensive understanding of postural control in children with differing neurological and medicative status.

Results: Children with ADHD did not sway more than typically developing peers but exhibited subtle differences in sway organization that depended on the specific nonlinear parameter (differences in fractal dimension, but not in entropy measures) and balance task (differences in static but not in dynamic balance). Group alterations occurred primarily at the level of biomechanical implementation rather than in the observable sway behavior. While both ADHD groups presented stiffer and more restrained hip-based control during static balance, the medicated group showed markedly higher torque amplitude and variation around the hip and upper body joint group during dynamic balance.

Conclusion: The present findings demonstrate that comparable balance performance can be achieved through fundamentally different biomechanical stabilization strategies. While neurotypical children show rich complexity that is well-adjusted to task demands, ADHD patients are more rigid in their postural control. This reverses with increasing balance demands; medicated ADHD patients achieve stabilization with highly variable proximal efforts, which is more likely to display over-recruitment than efficient, flexible postural adjustment. The dissociation between kinematic and kinetic measures emphasizes the importance of assessing not only the outcome of postural control, but also the mechanisms by which it is achieved.