This study is testing a new drug called *emraclidine* to see if it is safe for older adults. The study has two parts:

• Part A: For healthy adults aged 65 to 85.
• Part B: For adults aged 55 to 90 with Alzheimer's disease, a brain condition that causes memory loss.

Participants will need to take the drug by mouth. Researchers will watch for any side effects, or health problems caused by the drug. Participants need to be in good health and meet specific requirements to join. Some people cannot join, like those with serious mental health issues or a history of certain diseases.

• **Length of Study:** The study involves multiple doses, but the exact duration will be explained by the study team.
• **Compensation:** Participants may be compensated, details will be provided during enrollment.
• **Visits:** Regular visits for monitoring health and drug effects will be needed.

Consider joining if you're healthy or have stable Alzheimer's, and can commit to study requirements. Participants will have health checks and must follow rules for the study's safety.