This study is testing a medicine called trontinemab to see if it helps people with early signs of Alzheimer's disease (AD), which is a brain condition that affects memory and thinking. The study will check if the medicine is safe and works well for people with mild cognitive impairment (MCI) or mild dementia due to AD.

To join the study, participants need to be able to complete all study activities, like MRI scans (pictures of the brain), genetic tests, and other memory tests. They must also show signs of AD through special scans or tests. Participants will need a "study partner" to help with the study.

You cannot join if you have any other brain conditions or serious health issues that could impact the study.

• The study requires several brain tests, including MRI and memory tests.
• Participants need to have a helper, called a "study partner," during the study.
• You can’t participate if you have other serious health issues or different brain conditions.