ALX-001 is a first-in-class synapse targeted oral small molecule therapy for Alzheimer's disease. In this proposal, we intend to evaluate the biological and clinical effect of ALX-001 in patients with MCI and early AD. This 12-month, randomized, and placebo controlled study, patients will be administered either ALX-001 at a single dose strength or placebo. Changes in plasma and cerebrospinal fluid biomarkers of Alzheimer's pathology and synapse function will be assessed as a primary evaluation. Secondarily, we will seek to characterize the effect of ALX-001 on clinical outcomes and understand how ALX-001 may preserve cognition.