This study explores a special molecule called a **tracer** that can help see a protein in the brain using a method called **PET imaging**. The protein, **Hsp90**, is important because it helps other proteins take the right shape. If proteins don't fold correctly, it can lead to diseases like **Alzheimer's**, **Parkinson's**, and **ALS**. The study uses a tracer called **[¹¹C]HSP990** to measure Hsp90 levels in healthy people and those with these diseases. The results may help scientists develop new medicines targeting Hsp90.

• **Study Length and Visits:** Involves multiple PET scans and may require several visits.
• **Eligibility:** Participants include healthy individuals and those with specific diseases aged 18-85 years.
• **Potential Benefits:** May aid in developing treatments for neurodegenerative diseases.