['parkinson disease']
['sage-217', 'levodopa', 'antiparkinsonian agent(s)']

        Inclusion Criteria:

          -  Participant has a diagnosis of idiopathic Parkinson's Disease (Hoehn and Yahr Stage 2
             or Stage 3) with a duration of less than 7 years prior to screening [Part A]

          -  Participant has a diagnosis of idiopathic Parkinson's Disease (Hoehn and Yahr Stage
             1-4, assessed during the "on" period) [Part B]

          -  Participant is on a stable dose (at least 1 month prior to baseline visit) of an
             antiparkinsonian agent and is willing to remain on this dose for the duration of the
             study

        Exclusion Criteria:

          -  Participant has early (Hoehn and Yahr Stage 1) or advanced (Hoehn and Yahr Stage 4 or
             Stage 5) Parkinson's Disease [Part A]

          -  Participant has advanced (Hoehn and Yahr Stage 5) Parkinson's Disease [Part B]

          -  Participant with presence of drug-induced parkinsonism, metabolic identified
             neurogenetic disorders, encephalitis, or other atypical Parkinsonian syndromes

          -  Participant with medical history of electroconvulsive therapy or stereotaxic brain
             surgery for Parkinson's Disease

          -  Participant with medical history of suicide attempt within 2 years of screening or
             current suicidal ideation

          -  Participant with medical history of impulse control disorder
      