This study is for adults with **Lewy Body Dementia Psychosis (LBDP)**, a condition that affects the brain and can cause hallucinations. The study is called an **Open-Label Extension Study**, meaning every participant will know they are taking the medication ACP-204. The study lasts **52 weeks (one year)**. To join, you must have finished a previous related study and be able to attend study visits with a caregiver. Participants must agree to specific requirements, like not donating sperm if male, or ensuring birth control is used. **Eligibility Key Points:** - **Age and Completion:** Must have completed the earlier study and be an adult. - **Visits:** Must attend study visits with a caregiver. - **Health:** Should not have significant health issues that could interfere with the study. The study is not suitable if you have severe health issues, are bedridden, or have significant weight loss or a very low heart rate. For more details, visit the [study website](https://illumerastudy.com/).