Trontinemab is an experimental drug that is being developed for the possible treatment of AD. Trontinemab combines an anti-amyloid antibody with a brain shuttle module which helps to deliver the antibody to the brain. It works by preventing, blocking, and/or reducing the accumulation of beta amyloid plaques in the brain. The purpose of this study is to test the safety of trontinemab at different dose levels and to find out what effects, good or bad, trontinemab has on you and on early symptoms of AD.