This study examines if a single injection of **RE104** can help reduce anxiety symptoms for people with Generalized Anxiety Disorder, or **GAD**. GAD is a condition where people worry too much about many things. In this study, some people will get the RE104 injection, while others will receive a placebo, which looks like the real treatment but doesn't contain the active medicine. **Key Points to Consider:** - **Length of Study:** This study involves only a single dose of RE104. - **Eligibility:** Participants must have GAD, not be pregnant or planning to be, and cannot have certain other mental health conditions. - **Risks:** Participants with a high risk of suicide or other significant health conditions cannot join. If you have GAD and are interested in participating, make sure you don't have conditions like bipolar disorder or schizophrenia, and that you aren't using any restricted medications. It's crucial to ensure you don't have allergies to the study drug or related medications. This study aims to find effective treatments for anxiety, which could help many in the future.