Predicting Motor Sequence Learning in People with Parkinson Disease

Background and Purpose: Skill acquisition (ie, performance changes during practice) occurs in a nonlinear fashion. Despite this, motor learning is typically measured by comparing discrete timepoints. Thus, typical measures of motor learning do not detect skill acquisition characteristics that may be clinically meaningful. Reliable prediction of motor skill learning in people with Parkinson disease (PD) would allow therapists to more effectively individualize practice doses to fit specific patients' needs. The purposes of this study were to (a) characterize postural skill acquisition in people with PD, and identify factors (such as acquisition rate and practice dose to plateau) that predict learning, and (b) investigate whether levodopa medication (l-dopa) status during practice impacted learning. Methods: Twenty-seven adults with PD practiced a postural motor task over 3 days, followed by 2 retention tests. Participants were randomized to practice either ON or OFF l-dopa. Data for repeating and random sequences were each analyzed using nonlinear curve-fitting and mixed-effects regressions. Learning was defined as pretest minus retention test performance. Results: Participants with less physical impairment demonstrated less learning on the repeating and random sequence tasks compared with participants with more impairment. Participants who improved faster during practice demonstrated less learning on the repeating sequence task compared with participants who improved more slowly. Reaching plateau during practice was not related to learning. l-dopa did not impair learning. Discussion and Conclusions: Participants' skill acquisition characteristics were related to learning a postural motor task. Patient-specific factors, such as the rate of skill acquisition, level of physical function, and medication status, may influence how postural motor practice is delivered during balance rehabilitation. Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A250).