Donanemab Plus Usual Care for Early Alzheimer's Disease

Inclusion Criteria: Participants * are under care for presumed mild cognitive impairment (MCI) or mild dementia stage of AD (Note: neither a biomarker-based diagnosis of AD nor a diagnosis in electronic health records \[EHR\] is required prior to screening) * have a Telephone Interview for Cognitive Status (TICS) score of ≥21 * presence of amyloid beta (Aβ) pathology supported by biomarker results (e.g., P-tau, amyloid positron emission tomography (PET), and/or cerebrospinal fluid \[CSF\]). (Note: A historical biomarker may be used for eligibility if performed within 12 months of study entry) * have a reliable study partner who is in frequent contact with the participant and will be available by telephone at designated times (every 6 months), and * have EHR data available for linkage and are willing to allow access to EHR data for the duration of the study. Exclusion Criteria: * have prior ischemic or hemorrhagic stroke(s) with an inability to independently perform any one or more basic activities of daily living (ADLs) (i.e., walking, transferring, eating, bathing, dressing, or toileting). (Note: mixed dementias with amyloid pathology are permitted) * have current or recent serious or unstable illness (other than AD) that, in the investigator's opinion, could interfere with the ability of the participant or study partner to complete the study (e.g., life expectancy of less than 36 months, requirement for long-term (\>12 months) institutional-level care, serious psychiatric illness, etc.) * are currently enrolled or intend to enroll in a clinical trial of another investigational product, and * have contraindications to donanemab, magnetic resonance imaging (MRI), or amyloid PET tracers. (Donanemab group only).