Is Long-term Use of Amantadine Effective in PD?

The investigator aims to assess whether long-term use of amantadine is effective in patients with Parkinson's disease.

Amantadine is used in the early stages of Parkinson's disease (PD). However, amantadine is known to be relatively weak compared to other antiparkinsonian drugs such as levodopa, dopamine agonist or Mao-B inhibitor and its effects are limited in early months, so it is rarely used than other drugs. Recently, several studies have identified the long-term effects of amantadine on dyskinesia, but the basis is still insufficient. Therefore, this study aims to investigate the long-term effectiveness of amantadine in patients with PD. Participants who have used amantadine since the early stages of diagnosis undergo clinical evaluations including the Montreal Cognitive Assessment (MoCA), Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS), Freezing of Gait-Questionnaire (FOG-Q), Non-motor Symptom Scale (NMSS) and Parkinson's Disease Questionnaire-39 (PDQ-39). Then, participants stop taking amantadine. To investigate the long-term effect, clinical evaluations except MoCA are repetitively assessed at 4- and 8-week follow-ups.