A Study of LY3372993 in Healthy Participants and Participants With Alzheimer's Disease (AD)

Inclusion Criteria :

Part A:

- Overtly healthy males or females as determined by medical history and physical
examination

- Are between 18 to 45 years old, inclusive

- Male participants agree to use a reliable method of birth control during the study and
3 months following the last dose of the investigational product

- Female participants not of child-bearing potential

- Have a body mass index of 18.0 to 32 kilograms per square meter (kg/m²) inclusive

Part B:

- Present with mild cognitive impairment (MCI) due to Alzheimer's disease (AD) or
mild-to-moderate AD

- Positive florbetapir scan

- Men or nonfertile women, at least 55 years of age. Nonfertile is defined as
hysterectomy and/or bilateral oophorectomy, or amenorrhea for at least 1 year

- Have up to 2 study partners who can provide health information related to the study
about the participant. Study partner(s) will provide a separate written informed
consent to participate

Exclusion Criteria:

- Have significant abnormalities in brain magnetic resonance imaging (MRI); or have
contraindications for MRI

- Have significant allergic reactions to LY3372993, or related compounds, or have
significant allergies to humanized monoclonal antibodies, diphenhydramine,
epinephrine, or methylprednisolone

- Have clinically significant neurological or psychological illness, or other illnesses
that could affect the study results

Part A:

- Have family history of early onset Alzheimer's Disease (AD)

- Have impaired cognitive function

Part B:

- History of intracranial hemorrhage, cerebrovascular aneurysm or arteriovenous
malformation, or carotid artery occlusion, or stroke or epilepsy

- Previously dosed in any other study investigating active immunization against amyloid
beta (Aβ)

- Previously dosed in any other study investigating passive immunization against Aβ
within the last 6 months

- Have current serious or unstable illnesses