Inclusion Criteria:  Be between the age of 57 and 62 years at time of informed consent. Have a positive family history for dementia (minimum of 1 first degree relative). Previously known or documented heterozygote or homozygote ApoE ε4 allele. Be able to read and write and must have adequate hearing and visual acuity to complete the psychometric tests. Be otherwise healthy for their age group or medically stable with or without medication on the basis of physical examination, medical history, vital signs, and 12-lead ECG performed at screening or at baseline. Have Montreal Cognitive Assessment (MOCA) score of 27 or above. Have a creatinine clearance (CrCl), estimated using the Cockcroft-Gault formula, greater or equal to 30 mL/minute.  Exclusion Criteria:  A current clinical condition or requires a medication that raises the pH of their urine. Severe renal or hepatic impairment. Any other abnormality that could cause a possible cognitive deficit (including, but not limited to, vascular encephalopathy or large strokes). Contraindications for MRI (e.g., prostheses, implants, claustrophobia, pacemaker) or PET imaging. Neurodegenerative disorder known to cause neurocognitive decline Relevant history of or current neurological disease other than preclinical AD, which may make interpretation of possible new neurological signs or symptoms difficult. Clinically significant and active pulmonary, gastrointestinal, renal, hepatic, endocrine, or cardiovascular system disease Ongoing cancer treatment Clinically significant and active psychiatric disorder Use of an investigational medical device within 3 months before the planned start of study. Current participation in an interventional study with an investigational drug component. Major surgery (e.g., requiring general anesthesia) within 8 weeks before screening, or will not have fully recovered from surgery, or has major surgery planned during the time the subject is expected to participate in the study. Requires treatment with an AChE inhibitor or any of the following: acetazolamide, methazolamide, amantadine, ketamine, dextromethorphan.