The primary objective of the study is to evaluate the safety and tolerability of single and multiple intravenous (IV) infusions of Aducanumab in Japanese participants with mild to moderate Alzheimer's Disease (AD). The secondary objectives of this study are as follows: To evaluate the serum pharmacokinetics (PK) of Aducanumab after single and multiple intravenous (IV) infusions of Aducanumab; To evaluate the effect of single and multiple IV infusions of Aducanumab on immunogenicity.

Key Inclusion Criteria:

• Must be ambulatory
• Must have a clinical diagnosis of mild to moderate AD
• Must be in good health as determined by the Investigator, based on medical history and Screening assessments
• Must have a caregiver who, understands the study and assents to accompany the subject to all study site visits, provide information to the Investigator/study site staff, specifically about cognitive abilities and AEs/SAEs and return for per-protocol follow-up visits and procedures
• Must consent to blood sample collection for deoxyribonucleic acid (DNA; genotyping) and ribonucleic acid (RNA; for potential future analysis).

Key Exclusion Criteria:

• Any medical or neurological condition (other than AD) that in the opinion of the Investigator could be a contributing cause of the subject's dementia
• Transient ischemic attack or stroke or any unexplained loss of consciousness within 1 year prior to Screening
• Poorly controlled diabetes mellitus, as defined by having dosage adjustment of diabetic medication within the 3 months prior to Day 1
• History of unstable angina, myocardial infarction, chronic heart failure
• Chronic, uncontrolled hypertension
• History of seizure within 3 years prior to Screening
• History within the past 6 months or evidence of clinically significant psychiatric illness
• History of severe allergic or anaphylactic reactions, or history of hypersensitivity to any of the inactive ingredients in the drug product

NOTE: Other protocol defined Inclusion/Exclusion criteria may apply