A Study Evaluating the Efficacy and Safety of Crenezumab Versus Placebo in Participants With Prodromal to Mild Alzheimer's Disease (AD).

This randomized, double-blind, placebo-controlled, parallel group study will evaluate the efficacy and safety of crenezumab versus placebo in participants with prodromal to mild AD. Participants will be randomized 1:1 to receive either intravenous (IV) infusion of crenezumab or placebo every 4 weeks (Q4W) for 100 weeks. The final efficacy and safety assessment will be performed 52 weeks after the last crenezumab dose. Participants will then have the option to enter the Open Label Extension (OLE) study if eligible. Participants who do not enter the OLE study will have additional follow-up visits at 16 and 52 weeks after the last dose, primarily for safety and also for limited efficacy assessments.