Longitudinal Evaluation of Amyloid Risk and Neurodegeneration - the LEARN Study

Inclusion Criteria:

1. Consented to participate in the A4 study and previously met A4 demographic, cognitive
and clinical criteria (e.g., Mini-Mental State Examination (MMSE); Clinical Dementia
Ratin (CDR); Logical Memory test, part IIa (LMIIa); medications; medical history).

2. Has a florbetapir PET scan that falls below the Aβ threshold levels required for
randomization into the treatment arms of the A4 trial.

3. In general, permitted medications should be stable for 8 weeks prior to LEARN Visit 1.
Changes to medications that, in the opinion of the investigator, are not likely to
impact LEARN Visit 1 assessments are permissible.

4. Has a study partner that is willing to participate as a source of information and has
at least weekly contact with the subject (contact can be in-person, via telephone or
electronic communication). The study partner must have sufficient contact such that
the investigator feels the study partner can provide meaningful information about the
subject's daily function.

5. In the investigator's opinion, is both willing and able to participate in all required
procedures for the duration of the study (at least 168 weeks), including adequate
literacy in English or Spanish and adequate vision and hearing to complete the
required psychometric tests.

Exclusion Criteria:

1. Is receiving a prescription acetylcholinesterase inhibitor (AChEI) and/or memantine at
LEARN Visit 1

2. 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.

3. Has any contraindications for MRI studies, including claustrophobia, the presence of
metal (ferromagnetic) implants, or a cardiac pacemaker that is not compatible with
MRI.

4. Has a LEARN Visit 1 MRI scan with results showing >4 hemosiderin deposits (definite
microhemorrhages or areas of superficial siderosis); or any amyloid-related imaging
abnormalities - edema/effusions (ARIA-E).

5. Has received any exclusionary medication, including those with significant central
nervous system (CNS) anticholinergic effects, within 3 months prior to LEARN Visit 1
or initiated at any point after screen. A full list of exclusionary medication will be
provided in the relevant procedures manual.

6. Is currently enrolled in a clinical trial involving an investigational product or
non-approved use of a drug or device, or concurrently enrolled in any other type of
medical research judged not to be scientifically or medically compatible with this
study. Participation in observational studies may be permitted upon review of the
observational study protocol and approval by the Project Director or one of the ADCS
Medical Monitors.

For subjects participating in the optional Lumbar Puncture (LP, all of the above,
plus:

7. Current use of anticoagulants, such as warfarin or dabigatran.