This study checks for a problem called tau pathology in people with Parkinson's Disease (PD) using a special imaging method. Tau pathology is when a protein, called tau, builds up in the brain and may lead to problems like memory loss and movement issues. The study uses a tool called a PET scan, which is a type of camera that takes detailed pictures of the brain. They are testing a new PET camera called the NeuroEXPLORER. This study will take two years. In the first year, 30 people with different conditions, including PD, will be recruited. The second year will focus on following up with participants to see changes over time.

• The study lasts for 2 years with multiple visits for imaging.
• Participants may be scanned with new and old PET cameras for better comparison.
• Participants must be between 45-85 years old and follow specific guidelines for safety.