Novel lower-extremity dexterity assessment for Parkinson's disease: validation against measures of arm dexterity and general mobility.

Only 33 people with Parkinson's disease were studied, all recruited as part of a clinical trial. The medication order was not randomized: everyone was tested OFF first and ON second, so some improvement may reflect familiarity with the task. The foot task did not enforce accuracy; faster times could be achieved with less accurate foot placement, although researchers visually checked each tap and repeated poor trials. Several relationships were weak, and removing three outlier patients weakened many relationships; one relationship became not significant. The comparison gait tasks were done on flat, obstacle-free surfaces, so they may reflect gross movement rather than precise foot control. The study did not provide healthy comparison data or age-based norms, and it did not test other therapies such as deep brain stimulation. Because the foot task used a pre-specified pattern, poor performance may involve motor planning as well as foot control.

The authors report no conflict of interest. Participants were recruited as part of the SUNDIAL clinical trial, an NIH BRAIN Initiative study.

Do not conclude that this foot task improves Parkinson's symptoms or predicts falls. The study only tested how task times related to other measures in 33 people with Parkinson's disease, and it did not test falls, other therapies, or use in other populations.