A US company says it has devised a test to detect early signs of Parkinson's and Alzheimer's diseases.
Several teams are working on such a test but Power3 Medical Products could be the first to launch it in Europe this summer, Chemistry and Industry reports.
The diseases can currently only be diagnosed once symptoms develop.
UK experts said the test sounded promising for detecting and monitoring the diseases but more work was needed.
The company plans to launch the test in Greece first, before promoting it in the US by the end of the year.
It hopes the test could be launched in the UK early next year, if authorities are satisfied with trial results.
The test, called NuroPro, measures levels of 59 biomarkers - proteins in the blood, BBC says
The relative levels of the markers is used to distinguish between Alzheimer's, Parkinson's and another neurodegenerative disease called Lou Gehrig's disease.
So far, more than 180 patients have been tested, with the company claiming between 60% and 70% success in identifying those with Alzheimer's, Parkinson's or Lou Gehrig's.
Clinical trials are under way in the US and Greece.
Steve Rash, chief executive officer of the company, said: "There is currently no diagnostic test for any neurodegenerative disease on the market - diagnoses are currently based solely on a clinical diagnosis of symptoms."
Kieran Breen, director of research at the Parkinson's Disease Society, speaking at the start of Parkinson's Awareness Week, said it was currently difficult to diagnose the condition.
But he added: "Whilst the NuroPro test sounds promising, a larger study would need to be carried out before it can be confirmed as being helpful in making the diagnosis of Parkinson's.
"A blood test could also be particularly useful in monitoring the progression of Parkinson's and assessing agents or drugs that modify the rate of disease development."
The society is using the awareness week to highlight the need for people with Parkinson's to receive better specialist nursing care.
A survey of 13,000 people with the disease last year found 40% had not spoken to a specialist nurse in the previous year.
Susan Sorensen, head of research at the UK Alzheimer's Society, said:
"An effective blood test would present those diagnosed and their families with an opportunity to prepare for the impact of this devastating illness and make crucial decisions about their future.
But she said: "Opinion remains split on the potential effectiveness of a blood test, with some suggesting Alzheimer's is too complex to identify in this way.
Dr Sorensen said the test would also need to be usable on a large scale.