The progressive condition affects more than 150,000 people in the UK and is currently the world’s fastest-growing neurodegenerative disorder.

Parkinson’s encompasses a broad spectrum of conditions, with the most common symptoms being slowness of movement, tremors, and muscle stiffness.

There are currently no drugs that can slow or stop Parkinson’s, and efforts to develop preventative treatments are hampered by the inability to predict who will develop the condition.

Like many progressive neurological conditions, by the time symptoms emerge, significant brain cell damage caused by Parkinson’s has already occurred.

“At present, we are shutting the stable door after the horse has bolted, and we need to start experimental treatments before patients develop symptoms,” said Professor Kevin Mills at UCL Great Ormond Street Institute of Child Health, who helped develop the blood test.

Using machine learning, a form of artificial intelligence, researchers from University College London and University Medical Centre in Goettingen, Sweden, screened blood samples from people with Parkinson’s and identified eight key proteins or “biomarkers” common to those with the condition.

They then used their machine learning tool to analyse blood samples taken a decade ago from people with Rapid Eye Movement Sleep Behavior Disorder, around 75% of whom go on to develop Parkinson’s.

The AI has so far been able to correctly predict which patients went on to develop Parkinson’s, up to seven years before symptoms first appeared.

“By determining eight proteins in the blood, we can identify potential Parkinson’s patients several years in advance,” said Dr. Michael Bartl at UMC Goettingen.

“This means that drug therapies could potentially be given at an earlier stage, possibly slowing down disease progression or even preventing it from occurring.”

The researchers have more work to do to validate the test’s accuracy and develop a version that could be easily used in a clinic.

“If replicated in larger studies, these tests or panels may prove to be invaluable in supporting the diagnosis of Parkinson’s,” said neurologist Professor Ray Chaudhuri at King’s College London.

In the short term, a test could be used to replace the invasive lumbar puncture technique currently required to confirm Parkinson’s.

A blood test that predicts Parkinson’s years in advance may be key to accelerating clinical trials, but it raises ethical concerns, says Professor Chaudhuri.

Currently, doctors have no drugs to prevent or stop Parkinson’s—so is it right to offer people a test?

Gary Shaughnessy, diagnosed with Parkinson’s nine years ago, recognizes the dilemma.

He said, “I hate having Parkinson’s, so why would I want to know I have it for one second more than is absolutely necessary?”

However, he argues that there are actions people can take to mitigate the symptoms of Parkinson’s. His strategy is exercise—he’s a competitive marathon runner.

Shaughnessy also acknowledges that having a predictive test for Parkinson’s could be a key step toward developing new treatments.

“If we can make progress on a cure or treatments, it may be too late from my perspective, but if we could do something for other people, that would be brilliant,” he said.