Effect of Task Practice Order on Motor Skill Learning in Adults With Parkinson Disease: A Pilot Study

Background and Purpose: Random practice of motor tasks has been shown to enhance motor learning. The purpose of this study was to investigate the effects of task practice order (random, blocked) on motor learning in adults with Parkinson disease (PD). Subjects: Twenty adults with mild PD and 20 age-matched adults (controls) participated in the study. Methods: Participants in both groups (PD and control) practiced 3 movement tasks with either a blocked or a random practice order. This 2 participant group × 2 practice order design resulted in 4 experimental groups. The Trail Making Test was administered to all participants to determine task-switching capability. Motor performance on the arm movement tasks was quantified on the basis of the root-mean-square error difference between the goal movement task and each participant's response. Results: The task-switching capability of the control group was superior to that of the PD group. For acquisition, in general, participants in the control group performed with significantly less error than participants in the PD group. For retention, participants in the control group who practiced with a random order performed more accurately than participants in the control group who practiced with a blocked order. However, for the PD group, the findings were reversed; participants who practiced with a blocked order performed more accurately than participants who practiced with a random order. These findings resulted in a group × practice order interaction. Discussion and Conclusion: These pilot study data suggest that, contrary to the findings for age-matched control learners, for learners with mild PD, a blocked practice order may be better than a random practice order for motor learning.