Oxford University research has led to the creation of a new blood test for early Parkinson's disease identification.

The diagnostic tool can identify the disease's hallmark pathology even before significant symptoms show themselves.

Parkinson's disease, the second most common neurodegenerative disease globally, affects seven million people currently, with the numbers expected to double by 2040.

It starts over a decade before symptoms become severe enough for patients to seek clinical help, which is due to brain cells failing to manage a small protein called alpha-synuclein.

This results in the formation of abnormal clumps of the protein which can damage nerve cells, leading to a movement disorder and dementia in many cases.

The newly developed test measures a subtype of extracellular vesicles to spot shifts in alpha-synuclein in individuals predisposed to developing Parkinson's.

Professor George Tofaris, who led the research group, said: "A robust assay is crucial because neuronally-derived extracellular vesicles constitute less than ten percent of all circulating vesicles, and around 99 percent of alpha-synuclein in blood is released from peripheral cells, mostly red blood cells."

He added: "Collectively our studies demonstrate how fundamental investigations in alpha-synuclein biology can be translated into a biomarker for clinical application, in this case for the identification and stratification of Parkinson's risk.

"A screening test that could be implemented at scale to identify the disease process early is imperative for the eventual instigation of targeted therapies as is currently done with screening programmes for common types of cancer."

In the first research of its kind, the Oxford group studied 365 individuals deemed at risk.

They discovered that those deemed highest risk, over an 80 percent probability of developing the disease, had a two-fold increase in alpha-synuclein levels within neuronal extracellular vesicles.

The test could effectively distinguish a high-risk individual from a healthy control with a 90 percent probability.

This suggests that the blood test, paired with minimal clinical assessment, could help screen and identify individuals at a significant risk of Parkinson's.

Later analysis showed the test could also recognise individuals who had evidence of neurodegeneration identified through imaging or a pathology discovered through a spinal fluid assay but had not developed a movement disorder or dementia.

Within a small subgroup of 40 individuals who later developed Parkinson's or related dementia, the blood test was accurate in over 80 percent of cases up to seven years before diagnosis.

This suggests nerve cells may protect themselves by packing excessive alpha-synuclein in extracellular vesicles, released into the blood later.