Levodopa improves skilled hand functions in the elderly.

The endogenous dopamine system is a potent modulator of motor function and learning. Previous studies have demonstrated that, in the elderly, age-related degeneration of the nigrostriatal dopamine system may contribute to deficits in execution of skilled motor functions. The present double-blind, randomized cross-over study examined whether pharmacologically replenishing dopamine improves the execution of complex motor tasks. Twenty healthy young and 20 healthy elderly subjects were studied in two different sessions: (i) after three doses of levodopa (each 100 mg levodopa plus 25 mg carbidopa) and (ii) after three doses of placebo. For each session, subjects completed a functional motor test that reflects hand activities of daily living (Jebsen-Taylor test). In the elderly, but not in the young, Jebsen-Taylor test performance improved significantly (4%) with levodopa compared with placebo, particularly for fine motor functions. Attention to the task, level of fatigue, and positive and negative feelings were similar between sessions. These results demonstrate that increasing the dopaminergic drive pharmacologically may be helpful when the motor system is challenged in the ageing process.