The Effects of Medication and Parkinson’s Disease Severity on Proprioceptively Encoded Memory Guided Reaching (2877)

Objective: To examine the effects of medication (on vs. off) and PD severity (mild-to-moderate vs. advanced) on the performance of proprioceptively encoded memory guided reaching movements. Background: Proprioceptive inputs can be used to encode spatial locations and program movements to memorized locations. Studies suggest that the basal ganglia are involved in this proprioceptive-motor integration. Patients with Parkinson’s disease (PD), characterized by basal ganglia dysfunction, manifest deficits in proprioceptive-motor integration and impairments in memory guided movements. The effects of anti-Parkinsonian medication and PD severity on impairments during proprioceptively encoded memory guided movements remain unclear. Examining the effect of medication and PD severity will clarify the role of dopaminergic circuits during proprioceptively encoded memory guided reaching and the sustained effectiveness of medication as PD progresses. Design/Methods: Participants with mild-to-moderate (15m, 3f; mean age ± SD: 65.4±5.7 years; off motor UPDRS ± SD, 35.1±8.9) and advanced PD (11m, 3f; 66.2±4 years; 51±13.1) were blindfolded and performed a proprioceptively encoded memory guided reaching task while on and off medication (12-hour overnight withdrawal), over two separate days. Participants used proprioceptive inputs to encode targets (the examiner moved the blindfolded participant’s relaxed arm to three sequential locations), and then reached to the memorized targets as accurately as possible. Dependent outcomes included peak velocity and accuracy. All statistical analyses were performed using SAS Proc Mixed. Results: Medication had no effect on peak velocity and accuracy in the mild-to-moderate PD group. In the advanced PD group, medication significantly reduced error (mean difference, 0.03m; p Conclusions: Our finding that medication improves reaching accuracy of proprioceptively encoded targets in advanced PD supports the role of dopaminergic circuits in processing proprioceptive inputs during memory guided reaching. Further research is required to ascertain the scope of the proprioceptive deficit relative to healthy controls. Disclosure: Dr. Rivera has nothing to disclose. Dr. Entezar has nothing to disclose. Dr. Munoz has nothing to disclose. Dr. Pal has nothing to disclose. Dr. Verhagen Metman has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Abbott, AbbVie, and Boston Scientific. Dr. Goelz has nothing to disclose. Dr. Corcos has nothing to disclose. Dr. David has nothing to disclose.