Imagine getting a test that tells you about a protein in your brain linked to Parkinson's disease. You might wonder if that result changes as time goes on. This research followed 1,238 people from the Parkinson's Progression Marker Initiative to see if their test results held steady. The group included people already diagnosed with Parkinson's, those with early warning signs, and healthy individuals without the disease.
The results showed strong consistency for most. Among those with Parkinson's who tested positive for the protein, 96% stayed positive. Those who tested negative remained negative at a rate of 92%. For people with early signs of the disease, the test was even more stable, with 99% of positives staying positive and 95% of negatives staying negative.
However, the picture was less clear for healthy people. Only 89% of those who tested positive stayed positive, and 87% of those who tested negative stayed negative. The study did not report any safety issues or side effects. While this data points to a reliable test for patients, the variation in healthy controls reminds us that a single result does not guarantee a fixed outcome for everyone.