**Study of Trontinemab for Early Alzheimer's Disease** This study aims to check how well and safely trontinemab works for people with early Alzheimer's disease, a brain condition causing memory problems. Alzheimer's disease (AD) can start with mild thinking issues, known as mild cognitive impairment (MCI), and can progress to mild dementia. Participants will undergo various tests, like brain scans (MRI and PET) and genetic tests, to see how the medicine affects them. **Key Points:** - **Duration & Visits:** Participants need to complete all study activities over time, including several visits for tests. - **Compensation:** There may be compensation for participating, but this is not specified. - **Risks:** There are certain medical conditions that might prevent participation, ensuring safety is prioritized. Participants must be able to complete assessments, sometimes with a helper, and show signs of Alzheimer's, confirmed by scans or tests. Those with other brain-related conditions or unstable medical issues may not qualify. The study requires a partner to assist with the process. This research helps find better treatments for Alzheimer's disease.