Levodopa influences the regularity of the ankle joint kinematics in individuals with Parkinson's disease

The aim of the investigation was to explore the influence of levodopa therapy on the regularity of the structural variations present in the lower extremity joints of individuals with Parkinson's disease (PD). Ten participants with PD walked on a treadmill during the states of "off" and "on" levodopa. Approximate entropy was used to quantify the regularity of the structural variations present in the joint kinematics. Additionally, a pseudo-periodic surrogation analysis was used to evaluate if changes in the regularity of the joint's movement were associated with a noisy or deterministic motor process. This investigation provided two key findings. The first was that the structural variations present in ankle joint were more regular with levodopa therapy. The second was that changes in the structural variations were related to a deterministic motor process. This indicated that the variations present in the walking patterns of individuals with PD most likely arose from higher-order neural couplings rather than noise in the motor process. Monitoring the regularity of the structural variations present in gait may help improve the management of PD.