Levodopa Is a Double-Edged Sword for Balance and Gait in People With Parkinson's Disease
Funding agencies: This publication was made possible with support from a grant from the National Institute on Aging (AG006457), a Challenge Grant from the National Institute of Neurological Disorders and Stroke (RC1 NS068678) and from the Oregon Clinical and Translational Research Institute at Oregon Health & Science University, grant number UL1 RR024140 from the National Center for Research Resources, a component of the National Institutes of Health (NIH), and the NIH Roadmap for Medical Research.
Relevant conflicts of interest/financial disclosures: Oregon Health & Science University (OHSU) and Dr. Horak have a significant financial interest in APDM, a company that may have a commercial interest in the results of this research and technology. This potential institutional and individual conflict has been reviewed and managed by OHSU.
Full financial disclosures and author roles may be found in the online version of this article.
Abstract
Background
The effects of levodopa on balance and gait function in people with Parkinson's disease (PD) is controversial. This study compared the relative responsiveness to l-dopa on six domains of balance and gait: postural sway in stance; gait pace; dynamic stability; gait initiation; arm swing; and turning in people with mild and severe PD, with and without dyskinesia.
Methods
We studied 104 subjects with idiopathic PD (H & Y II [n = 52] and III–IV [n = 52]) and 64 age-matched controls. Subjects performed a mobility task in the practical off state and on l-dopa: standing quietly for 30 seconds, initiating gait, walking 7 meters, and turning 180 degrees. Thirty-four measures of mobility were computed from inertial sensors. Standardized response means were used to determine relative responsiveness to l-dopa.
Results
The largest improvements with l-dopa were found for arm swing and pace-related gait measures. Gait dynamic stability was unaffected by PD and not responsive to l-dopa. l-dopa reduced turning duration, but only in subjects with severe PD. In contrast to gait, postural sway in quiet standing increased with l-dopa, especially in the more severely affected subjects. The increase in postural sway, as well as decrease in turning duration and exaggerated arm swing with l-dopa was observed only for subjects with dyskinesia at the time of testing.
Conclusions
The observed spectrum of l-dopa responsiveness in balance and gait measures suggests that multiple neural circuits control balance and gait. Many of the negative effects of l-dopa may be directly or indirectly caused by dyskinesia. © 2015 International Parkinson and Movement Disorder Society
