Inclusion Criteria:

• Consent to receive disclosure of their risk estimates to develop clinical symptoms of AD based on their APOE genotype.
• Male or female, age 60 to 75 years inclusive. Females must be considered post-menopausal and not of child bearing potential.
• Mini-Mental State Examination (MMSE) total score ≥ 24 (at screening or in previous 3 months) and cognitively unimpaired as evaluated by memory tests performed at screening.
• Homozygous APOE4 genotype.
• Participant's willingness to have a study partner.

Exclusion Criteria:

• Any disability that may prevent the participants from completing all study requirements.
• Current medical or neurological condition that might impact cognition or performance on cognitive assessments.
• Advanced, severe progressive or unstable disease that may interfere with the safety, tolerability and study assessments, or put the participant at special risk.
• History of malignancy of any organ system, treated or untreated, within the past 60 months.
• History of hypersensitivity to any of the investigational drugs or their excipients / adjuvant or to drugs of similar chemical classes.
• Indication for, or current treatment with ChEIs and/or another AD treatment (e.g. memantine).
• Contraindication or intolerance to MRI or PET investigations (with fluorinated radio ligands).
• Brain MRI results showing findings unrelated to AD that, in the opinion of the Investigator might be a leading cause to future cognitive decline, might pose a risk to the participant, or might prevent a satisfactory MRI assessment for safety monitoring.
• Suicidal Ideation in the past six months, or Suicidal Behavior in the past two years.
• A positive drug screen at Screening, if, in the Investigator's opinion, this is due to drug abuse.
• Significantly abnormal laboratory results at Screening, or infection not as a result of a temporary condition.
• Current clinically significant ECG findings. For Cohort - I only: Participants with previous organ transplantation or stem cell transplantation, or indication for treatment with anti-coagulants.

For Cohort - II only: Participants with depigmenting or hypopigmenting conditions (e.g. albinism vitiligo) or active / history of chronic urticarial in the past year.