A Study to Evaluate the Safety and Tolerability of SAGE-718 in Participants With Mild Cognitive Impairment or Mild Dementia Due to Alzheimer's Disease (AD)

An Open-Label Evaluation of the Safety and Tolerability of SAGE-718 in Participants With Mild Cognitive Impairment or Mild Dementia Due to Alzheimer's Disease

The primary purpose of this study is to evaluate the safety and tolerability of SAGE-718 and its effects on cognitive and neuropsychiatric symptoms in participants with mild cognitive impairment (MCI) or mild dementia due to Alzheimer's disease (AD).

Inclusion Criteria:

1. Participant meets the following criteria for MCI or mild dementia due to AD at Screening: has a memory complaint, has clinical dementia rating (CDR) score of 0.5 to 1.0 (inclusive) with a memory box score ≥0.5, has essentially preserved activities of daily living
2. Participant has a score of 15 to 24 (inclusive) on the Montreal Cognitive Assessment at Screening
3. Participant has normal premorbid intelligence quotient (IQ) at Screening
4. Participant has a study partner who is reliable, competent, at least 18 years of age, willing to be available to the study center by phone, support study-specific activities, and accompany the participant to study visits as needed

Exclusion Criteria:

1. Participant has any medical or neurological condition (other than AD) that might be contributing to the participant's cognitive impairment or history of cognitive decline
2. Participant has 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
3. Participant has a history, presence, and/or current evidence of a clinically-significant intracranial abnormality (eg, stroke, hemorrhage, space-occupying lesion) that could account for the observed cognitive impairment (excluding abnormalities consistent with underlying AD pathology)
4. Participant has a history of possible or probable cerebral amyloid angiopathy, according to the Boston Criteria
5. Participant has a history of seizures or epilepsy, with the exception of a single episode of febrile seizures in childhood
6. Participant has current or recent suicidality