Additional Study Information: This is a Phase II, randomized, double-blind, placebo-controlled, parallel-group study that will evaluate the efficacy, safety and tolerability, pharmacokinetics, and pharmacodynamics of the study drug (an antibody to the tau protein called MTAU9937A) in patients with prodromal or mild Alzheimer's disease. The study consists of a screening period, a double-blind treatment period, an optional open-label extension (OLE) period, and a safety follow-up period.