Do motor subtypes of Parkinson’s disease impact the learning of motor tasks?

BACKGROUND:Previous studies have demonstrated that people with Parkinson's disease (PD) can acquire postural control skills even with the degeneration of motor areas responsible for consolidation of the representation regarding the learned motor skill in long-term memory. However, these findings have not considered the PD motor subtypes – tremor-dominant (TD), and postural instability and gait difficulty (PIGD). Although there is considerable heterogeneity in motor and non-motor symptoms between TD and PIGD, no study has addressed the effect of the PD subtype on learning postural control skills. AIM:We investigated the influence of PD motor subtypes on the learning of tasks with different postural control demands. METHOD:Fourteen individuals with PD (7 TD, 7 PIGD) practiced four motor tasks with high postural and cognitive demands. Participants completed 13 one-hour sessions (2x/week for 7 weeks). We considered the first and last practice sessions, pre-test and post-test, respectively. Also, we conducted one-week and one-month retention tests to assess performance persistence (motor learning). We assessed motor performance through the scores achieved on each motor task. RESULTS:Both groups demonstrated improvement in performance during the acquisition phase. However, the TD group outperformed the PIGD group in all motor tasks, despite both groups showing improvement in motor performance when comparing the results of pre-test with the post-test, and the improved performance was maintained in retention tests. The performance differences between groups are dissipated during consolidation, and they did not directly affect motor learning. INTERPRETATION: The TD and PIGD motor subtypes learned postural control tasks with different motor and cognitive demands.