Inclusion Criteria:

• Has a Mini-Mental State Examination (MMSE) score at screening of 25 to 30
• Has a global Clinical Dementia Rating (CDR) scale score at screening of 0
• Has a Logical Memory II score at screening of 6 to 18
• Has a florbetapir positron emission tomography (PET) scan that shows evidence of brain amyloid pathology at screening
• Has a study partner that is willing to participate as a source of information and has at least weekly contact with the participant (contact can be in-person, via telephone or electronic communication)

Exclusion Criteria:

• Is receiving a prescription acetylcholinesterase inhibitor (AChEI) and/or memantine at screening or baseline
• Lacks good venous access, such that intravenous drug delivery or multiple blood draws would be precluded
• Has current serious or unstable illness including cardiovascular, hepatic, renal, gastroenterologic, respiratory, endocrinologic, neurologic, psychiatric, immunologic, or hematologic disease or other conditions that, in the investigator's opinion, could interfere with the analyses of safety and efficacy in this study
• Has had a history within the last 5 years of a serious infectious disease affecting the brain (including neurosyphilis, meningitis, or encephalitis) or head trauma resulting in protracted loss of consciousness
• Has had a history within the last 5 years of a primary or recurrent malignant disease with the exception of any in situ cancer that was appropriately treated and is being appropriately monitored, such as resected cutaneous squamous cell carcinoma in situ or in situ prostate cancer with normal prostate-specific antigen post-treatment
• Has a known history of human immunodeficiency virus (HIV), clinically significant multiple or severe drug allergies, or severe post-treatment hypersensitivity reactions (including, but not limited to, erythema multiforme major, linear immunoglobulin A dermatosis, toxic epidermal necrolysis, or exfoliative dermatitis)
• Is clinically judged by the investigator to be at serious risk for suicide
• Has a history within the past 2 years of major depression or bipolar disorder as defined by the most current version of the Diagnostic and Statistical Manual of Mental Disorders (DSM)
• Has a history within the past 5 years of chronic alcohol or drug abuse/dependence as defined by the most current version of the DSM