Scientists have identified 11 proteins that they say are more than 90% accurate at predicting whether a person will be affected by the disease in future.

The proteins, found in the blood's plasma, are markers for the biological changes that happen in people who have dementia or Alzheimer's disease.

One protein - known as GFAP - has previously been identified as a potential biomarker in smaller studies.

The researchers, from the University of Warwick and Fudan University in China, described their findings, published in the journal Nature Aging, as a "breakthrough".

Professor Jianfeng Feng, from the University of Warwick's department of computer science, said the test "could be seamlessly integrated into the NHS and used as a screening tool by GPs".

There are more than 944,000 people in the UK who have dementia, which is expected to rise to more than a million by 2030.

'Immense significance'

The researchers said an early diagnosis is critical for those with the condition - as there are new drugs that can slow progression of the disease if detected early enough.

Jia You, of Fudan University, said early screening "holds immense significance in pinpointing dementia risks".

He said: "A notable advantage of plasma protein analysis is that it merely necessitates routine blood tests, similar to those conducted during regular hospital visits or health checks.

"This simplicity offers a considerable edge over more invasive procedures like lumbar punctures, especially where the targeting population are healthy individuals."

The researchers looked at data from more than 50,000 healthy people from UK Biobank, which holds medical and lifestyle records of more than half a million Britons.

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They analysed the blood samples from the group collected between 2006 and 2010.

Over a follow-up period of 10 to 15 years, more than 1,400 people went on to develop dementia.

By analysing more than 1,400 different proteins in the blood and using artificial intelligence, the researchers found 11 proteins that could accurately predict dementia up to 15 years before diagnosis.

Dr Richard Oakley, associate director of research and innovation at Alzheimer's Society, said: "It's very early days and lots more work is needed but this could lay the groundwork for the early prediction of dementia and teach us more about how to provide an early and accurate diagnosis.

"What we need now are blood tests that work in a real-world setting and that can accurately diagnose dementia when someone is starting to show symptoms."