Introduction. Dopamine-replacement medications may improve mobility while not improving responses to postural challenges and could therefore increase fall risk. The purpose of this study was to measure reactive postural responses and gait-related mobility of patients with PD during ON and OFF medication conditions. Methods. Reactive postural responses to the Pull Test and performance of the Functional Gait Assessment (FGA) were recorded from 15 persons with PD during ON and OFF medication conditions. Results. Persons with PD demonstrated no significant difference in the reactive postural responses between medication conditions but demonstrated significantly better performance on the FGA when ON medications compared to OFF. Discussion/Conclusion. Dopamine-replacement medications alone may improve gait-related mobility without improvements in reactive postural responses and therefore could result in iatrogenic increases in fall risk. Rehabilitation providers should be aware of the side effects and limitations of medication treatment and implement interventions to improve postural responses. 1. Introduction Parkinson disease (PD) is the most prominent of the hypokinetic disorders [1, 2]. The cardinal features of PD are tremor at rest, rigidity, hypokinesia, and postural instability [3, 4]. Postural instability and falls constitute major reasons for the serious complications in advanced PD [5, 6]. Falls are associated with high morbidity, mortality [7], and diminished quality of life [8, 9]. Current estimates report that up to 70% of those with PD fall each year, and 13% fall more than once a week [5, 10]. The majority of persons with PD will be treated with dopamine-replacement medications and the benefits of these medications on overall motor function and mobility are well established [11, 12]. However, limitations of dopamine replacement do exist. One of these limitations is the minimal effect of dopamine-replacement medications on postural instability [13–15]. Coupling the benefits of increased gait-related mobility and the limitation that postural instability is dopamine-resistant raises the possibility that fall risk may increase through increased exposure to postural challenges. With such a high incidence of falls and the apparent dopamine-resistant nature of postural instability, an understanding of the extent and character of how postural responses and gait-related mobility respond to dopamine-replacement medication is critical for optimal rehabilitative treatment. Despite the apparent paradox between dopamine replacment effects on postural
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