Inclusion Criteria:

• Diagnosis of prodromal AD, including the following
  • History of subjective memory decline with gradual onset and slow progression for at least one year corroborated by an informant,
  • Objective impairment in episodic memory by memory test performed at Screening,
  • Does not meet criteria for dementia, AND
  • Positive Screening amyloid imaging PET scan using [18F]flutametamol tracer or positive Screening CSF tau:amyloid-β42 (Aβ42) ratio
• Able to read at a 6th grade level or equivalent
• If participant is receiving an acetylcholinesterase inhibitor or memantine, the dose must have been stable for at least three months before Screening
• Must have a reliable and competent trial partner/informant who has a close relationship with the participant and is willing to accompany the participant to all required trial visits, and to monitor compliance of the administration of the trial medication

Exclusion Criteria:

• History of stroke
• Evidence of a clinically relevant neurological disorder other than the disease being studied (i.e., prodromal AD)
• History of seizures or epilepsy within the last 5 years
• Evidence of a clinically relevant or unstable psychiatric disorder, excluding major depression in remission
• Participant is at imminent risk of self-harm or of harm to others
• History of alcoholism or drug dependency/abuse within the last 5 years before Screening
• Participant does not have a magnetic resonance imaging (MRI) scan obtained within 12 months of Screening and is unwilling or not eligible to undergo an MRI scan at the Screening Visit. With Sponsor approval, a head computed tomography (CT) scan may be substituted for MRI scan to evaluate eligibility
• History of hepatitis or liver disease that has been active within the 6 months prior to Screening
• Recent or ongoing, uncontrolled, clinically significant medical condition within 3 months of Screening
• History of malignancy occurring within the 5 years before Screening, except for adequately treated basal cell or squamous cell skin cancer, in situ cervical cancer, or localized prostate carcinoma
• Clinically significant vitamin B12 or folate deficiency in the 6 months before Screening
• Use of any investigational drugs or participation in clinical trials within the 30 days before Screening
• History of a hypersensitivity reaction to more than three drugs
• Has human immunodeficiency virus (HIV) by medical history
• Participant is unwilling or has a contraindication to undergo PET scanning including but not limited to claustrophobia, excessive weight or girth
• History or current evidence of long QT syndrome, corrected QT (QTc) interval ≥470 milliseconds (for male participants) or ≥480 milliseconds (for female participants), or torsades de pointes
• Close family member (including the trial partner, spouse or children) who is among the personnel of the investigational or sponsor staff directly involved with this trial