The Immediate Effect of Rhythm on the Timing of Upper Extremity Movements in Patients with Parkinson's Disease

of a thesis at the University of Miami. Parkinson's disease is a neurodegenerative disease caused by a loss of dopamine-producing neurons in the basal ganglia. Primary motor deficits include resting tremor, bradykinesia, muscular rigidity, and postural instability. Most importantly, patients have difficulty both initiating movements and performing well-timed movements. This study explored the effect of rhythm on the timing of upper extremity movements in patients with Parkinson's disease. Comparisons were made between an external rhythmic cue, an external rhythmic cue in combination with auditory feedback, and no cue. Fifteen participants performed a simple reaching task in each of the four cueing conditions with the use of an interactive touch table. Condition 1 consisted of no cue. Condition 2 included a metronome set to the participant's baseline tempo. Condition 3 included a metronome set to the participant's baseline tempo, and a synthesized tone that occurred as a result of contact with the table. Finally, Condition 4 included no cue, similar to Condition 1. Participants were placed into either a mild/moderate level of impairment group, or a severe level of impairment group. Data were collected for total movement time, initiation time, and delta time for each participant in all four conditions. Results of the study did not reveal a main effect of condition on total movement time, initiation time or delta time. However, post-hoc pair-wise comparisons revealed significant decreases between Condition 1 and Condition 4, which were both uncued conditions, for both total movement time and delta time. In addition, for total movement time, a significant decrease was found between Condition 2 (external rhythmic cue) and Condition 4 (no cue). An immediate effect of cueing was found for initiation time and delta time, but did not reach a level of significance. An immediate effect of cueing on total movement time was not evident. Overall, from Condition 1 to Condition 2 as well as Condition 1 to Condition 3, initiation time and delta time decreased, but total movement time did not. Further analysis of level of impairment could not be conducted because of the small number of participants in the severe level of impairment group. The results suggest that one auditory cue was not more beneficial than the other for improving total movement time, initiation time, or delta time. In addition, the improvement from Condition 1 to Condition 4 for total movement time and delta time suggests that a practice effect was evident …