The main purpose of this study is to evaluate the long-term effectiveness of donanemab plus usual care versus usual care alone in participants with early symptomatic AD. The study will employ a prospective, observational cohort design with participant management resembling real-world practice to the greatest extent possible via prospective assessments and linkage to historical and prospective electronic health records. The study will last about 273 weeks and may include up to 28 visits.

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).

The study population will consist of a donanemab plus usual care group and a usual care alone group. Participants will be enrolled 1:2 into donanemab plus usual care and usual care alone groups to allow enough participants in the usual care group to be matched with participants in the donanemab group to enable robust comparative effectiveness analyses.

Anonymized individual patient level data will be provided in a secure access environment upon approval of a research proposal and a signed data sharing agreement.

Data are available 6 months after the primary publication and approval of the indication studied in the US and European Union (EU), whichever is later. Data will be indefinitely available for requesting.