Characteristic difficulty in rhythmic movement with aging and its relation to Parkinson's disease

Abstract

A total of 137 healthy participants aged from 20 to 79 years, including 59 over 60 years, were examined using a finger-tapping test. The test requested the participant to respond synchronously with the right middle finger to a periodic sound train with frequencies of 1, 2, 3, 4, and 5 Hz (cycles/sec). Difficulty keeping the rhythmic movement at a given rate was found to be a characteristic of aging. For the participants over 30 years, the mean rate of tapping deviated towards a faster rate for the stimulus frequency at 4 or 5 Hz (hastened tap, HT). The percentage of the participants who exhibited HT increased with decade of age; 0(20s), 11(30s), 13(40s), 17(50s), 30(60s) and 29(70s). HT in aging appears similar to hastened tapping which is typically observed in patients with Parkinson's disease and may be related to extrapyramidal dysfunction. Hastened tapping in the elderly supports the hypothesis that Parkinson's disease is a model for premature aging, suggesting that HT in aging represents an extrapyramidal motor dysfunction due to the neuroanatomical and neurochemical changes in the nigro-striatal system of the aging brain.