An Open-Label Evaluation of the Safety and Tolerability of SAGE-718 in Participants With Parkinson’s Disease Mild Cognitive Impairment

1. Meet the following criteria for PD-MCI: Have a confirmed diagnosis of idiopathic PD
according to 2015 Movement Disorder Society (MDS) clinical diagnostic criteria; Meet
MDS Task Force Criteria for MCI in PD.

2. Have a score of 20 to 25 (inclusive) on the Montreal Cognitive Assessment (MoCA) at
Screening.

3. Meet criteria for Hoehn & Yahr Stage I to III (mild to moderate motor severity) at
Screening.

4. Have stable motor symptoms for at least 8 weeks, in the opinion of the investigator.

Exclusion Criteria:

1. Have a diagnosis of dementia of any etiology, including but not limited to: Dementia
associated with PD (probable or possible), Dementia with Lewy Bodies, Alzheimer’s
Dementia, and Vascular Dementia.

2. Have any indication of parkinsonism other than idiopathic PD.

3. In the opinion of the investigator, be experiencing unpredictable fluctuations in
motor and/or nonmotor symptoms associated with PD.

4. Have a diagnosis of an ongoing central nervous system condition other than idiopathic
PD, including active neurologic and/or nonremitted psychiatric disorders.

5. Have a history of brain surgery, deep brain stimulation, a significant head injury
causing loss of consciousness greater than 30 minutes, or hospitalization due to a
brain injury.

6. Have experienced psychotic symptoms within the past 3 months, including those
associated with PD medications, as determined by a ‘yes’ answer to item A or item B on
the Neuropsychiatric Inventory-Questionnaire completed during Screening.