Analysis of the course of Parkinson's disease under dopaminergic therapy: performance of "fast tapping" is not a...

In addition to clinical rating scales, instrumental methods are employed frequently for assessment of performance or motor deficits in Parkinson's disease (PD). Many studies have analyzed such parameters in cross-sectional studies. We employed a battery of tests to investigate fine motor performance over a period of 4 years in 411 de novo parkinsonian patients from the Prado study. Specifically, tapping and pegboard testing ("plugging") were evaluated and performance on these tests compared with clinical ratings. Plugging scores correlated well with tapping scores and clinical rating at each assessment timepoint. Both tests also showed significant differences to healthy controls. Nevertheless "fast tapping" was found to be less impaired than was plugging in de novo patients. Over time, it was observed that plugging scores, but not tapping scores, exhibited changes that paralleled movements in clinical score. Plugging scores exhibited a marked response to dopaminergic therapy whereas fast tapping showed no therapeutic response. Fast tapping is certainly not suitable for assessment of bradykinesia or hypokinesia, and does not respond to dopaminergic therapy.