Synucleinopathies are rare diseases where the body has too much of a protein called α-synuclein in the nervous system. This can cause problems like moving slowly, trouble with coordination, or memory issues. These diseases usually start in people over 50 years old. Common types are Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). Sometimes, the first signs happen outside the brain, such as trouble with digestion, urination, or blood pressure, before affecting the brain. The study aims to learn how synucleinopathies change over time and find clues to predict who might develop further problems.

• The study involves follow-up visits at various centers.
• Participants must be 18 or older and have specific symptoms.
• Excludes those with conditions like diabetes, heart failure, or drug-related issues.