Use of sensitive devices to assess the effect of medication on attentional demands of precision and power grips in individuals with Parkinson disease.

Deficits in fine motor control are a common early symptom in people with Parkinson disease (PD) and may serve as an ideal marker for the response to therapeutic interventions and progression of the disease. The long-term goal of this research is to develop sensitive clinical markers that can be used to accurately assess disease progression and the response to therapeutic interventions. The purpose of this preliminary study was to examine the effects of medication on the attentional demands of precision (Pre) and power (Pow) grips in individuals with PD. In order to assess force control during precision and power grip, we used an instrumented twist-cap device. Performance on the motor task was quantified using peak force levels (PF) and the time to reach peak force (TTP). To assess attentional demands of the motor task, participants performed an auditory analog of the Stroop test while performing the motor task. Dual-task cost (DTC) for all outcome variables was calculated. Dual-task cost for response latency (RL DTC) for both grips were greater (P < 0.005) when participants were on medications('ONMeds'). Mean [95%CI]: Pre = 25.7[14.7-36.7], Pow = 37.08[26.5-47.7]) compared with off medications('OFFMeds') (Pre = 12.6[1.5-23.6], Pow = 10.98[0.4-21.6]), suggesting that force control during both grip tasks may remain attentionally demanding even on medications.