This study focuses on understanding if people with Essential Tremor (ET) might develop Parkinson's Disease (PD). ET causes uncontrollable shaking, mainly in the hands, and affects many older adults. Some with ET might develop PD, a brain disorder that leads to shaking and difficulty with movement. The study uses the Syn-One Test, a method that involves taking a small piece of skin (a skin biopsy) to check for signs of a protein called phosphorylated alpha-synuclein (P-SYN) linked to Parkinson's. This test is less invasive and costly than other methods.

• The study is for people aged 50-85 who have ET or ET-Plus, which includes additional mild neurological symptoms.
• Participants must be willing to undergo the Syn-One Test and other study procedures.
• People with certain health issues, like severe heart disease or ongoing neurological disorders, cannot join.