A blood test for Alzheimer's disease could be available on the NHS within five years, experts have said. 

Alzheimer's Research UK and the Alzheimer's Society have launched a £5 million project to bring simple tests to the health service, with the hope of speeding up diagnosis and reaching more people.

At present, accurately diagnosing people with Alzheimer's as opposed to other causes of dementia is complicated because it relies on either brain imaging using PET scans, which the NHS has comparatively few of per head of population, or invasive and painful lumbar punctures where a sample of cerebrospinal fluid is drawn from the lower back.

Very few patients are formally diagnosed. 

READ MORE: Could a blood test detect Alzheimer's early?

Now, thanks to £5 million of funding from the People's Postcode Lottery, the charities are working with the National Institute for Health and Care Research to make blood tests on the NHS a reality.

A range of tests for Alzheimer's are currently in the research stages, including those looking for specific proteins that occur before dementia symptoms even appear.

Pharmaceutical giants Roche and Eli Lilly have also announced that they have joined forces to develop a blood test for Alzheimer's disease.

Some tests are already being used in private clinics in Hong Kong and the US, but UK charities say more work is needed to ensure tests are measuring the right combination of biomarkers.

The need for blood tests to diagnose Alzheimer's has become more pressing since the medicines donanemab and lecanemab were found to slow cognitive decline.

Both these drugs made headlines around the world and are set to be assessed for use in the UK.

However, they are only suitable for patients who have Alzheimer's disease and must be administered at an early stage to slow disease progression.

READ MORE: The landscape for Alzheimer's is changing - can the NHS catch up?

Blood tests are seen as a simple way to speed up diagnosis and distinguish cases of Alzheimer's from other causes of dementia. 

Dr Susan Kohlhaas, executive director of research and partnerships at Alzheimer's Research UK, said: "We expect more people to be coming forward for diagnosis, we expect them to be coming forward at a younger age and we expect them to be coming forward with less obvious symptoms.

"We need better, more scalable tests that are also accurate and compare to current gold standard methods."

She added that healthcare systems are "on the cusp of a new era of dementia treatments" but "the NHS doesn't possess the required levels of diagnostic infrastructure to cope with this growing demand".

She added: "Currently only 2% of people are offered advanced diagnostic tests like PET scans and lumbar punctures.

"Significant investment is needed to ensure the NHS has the right tools to identify people with dementia much earlier than it is currently able to.

"Low-cost tools like blood tests that are non-invasive and simpler to administer than current gold standard methods are the answer to this.

"But we need to move these tests out of the lab and assess their effectiveness in real-world settings like the NHS."

READ MORE: Alzheimer's drug hailed as 'beginning of the end' for disease 

The new project - the Blood Biomarker Challenge - will work with world-class researchers to pilot new blood tests in the NHS that can diagnose different forms of dementia earlier and more accurately.

There is no suggestion as yet the tests could be used for mass population testing.

Fiona Carragher, director of research and influencing at the Alzheimer's Society, said: "New drugs targeting early-stage Alzheimer's disease are just around the corner, but without a diagnosis, people simply won't be able to access them if they are approved."

She said introducing a blood test for dementia into UK healthcare systems would be "a truly game-changing win in the fight against this devastating disease."

Dementia affects around 900,000 people in the UK and experts predict that will rise to 1.4 million people by 2040.