Short-term effect of amantadine sulphate on motor performance and reaction time in patients with idiopathic Parkinson's disease.

In thirty patients with idiopathic Parkinson's disease (PD) we examined in a prospectively designed study the effect on motor performance and cognitive functions of amantadine sulphate, applied intravenously over a period of 14 days. Prior to the introduction of amantadine and post infusionem the motor function was measured by the Unified Parkinson Disease Rating Scale (UPDRS) and the Motor Performance Test Series (MPS); the simple and the choice reaction time were assessed using the Vienna Reaction Unit (VRU). The primary endpoint of efficacy was the change in the UPDRS part III (motor examination) after 14 days of amantadine sulphate administration compared with baseline. Secondary end-points were changes in the variables of-the MPS and VRU at the end of administration interval compared with baseline. Overall, after 14 days of intravenous amantadine administration (200mg/ day), a significant improvement was obtained in motor performance with respect to the semiquantitative motor scores of the UPDRS (p = 0.002) and the quantitative motor variables in the pertinent subtests of the MPS, reflecting precision and speed of arm-hand movement as well as manual and finger dexterity, for the right (p < 0.01) and the left hand (p < 0.05). However, all patients being viewed collectively, it was observed that there was a widely differing time delay of efficient motor response to amantadine from 4 to 9 days between individuals, whilst the quality of motor response remained stable for the follow-up period. Although simple reaction time showed no significant improvement, choice reaction time shortened significantly in less affected PD patients staging Hoehn and Yahr I to III (p < 0.05). We conclude that apart from efficacy on motor performance, amantadine sulphate - applied intravenously - has a positive effect on cognitive functions, particularly in less affected PD patients.