Experts say a blood test has the potential to revolutionize Alzheimer’s diagnosis

A blood test for detecting Alzheimer’s disease could be just as accurate as painful and invasive lumbar punctures and could revolutionise diagnosis of the condition, research suggests.

Measuring levels of a protein called p-tau217 in the blood could be just as good as lumbar punctures at detecting the signs of Alzheimer’s, and better than a range of other tests under development, experts say.

The protein is a marker for biological changes that happen in the brain with Alzheimer’s disease.

In a study of 786 people, researchers were able to use the ALZpath p-tau217 test to identify patients as being likely, intermediate or unlikely to have Alzheimer’s disease.

Dr Richard Oakley, an associate director of research and innovation at the Alzheimer’s Society, said: “This study is a hugely welcome step in the right direction as it shows that blood tests can be just as accurate as more invasive and expensive tests at predicting if someone has features of Alzheimer’s disease in their brain.

“Furthermore, it suggests results from these tests could be clear enough to not require further follow-up investigations for some people living with Alzheimer’s disease, which could speed up the diagnosis pathway significantly in future. However, we still need to see more research across different communities to understand how effective these blood tests are across everyone who lives with Alzheimer’s disease.”

Currently, the only way to prove that someone has a buildup of the proteins in the brain is to have a lumbar puncture or an amyloid PET scan, which are available in only about one in 20 NHS memory clinics. A lumbar puncture involves a needle being inserted into the lower back, between the bones in the spine.

Dr Sheona Scales, a director of research at Alzheimer’s Research UK, said: “This study suggests that measuring levels of a protein called p-tau217 in the blood could be as accurate as currently used lumbar punctures for detecting the biological hallmarks of Alzheimer’s disease, and superior to a range of other tests currently under development. This adds to a growing body of evidence that this particular test has huge potential to revolutionise diagnosis for people with suspected Alzheimer’s.”

She said a better picture was needed of how these types of blood tests performed in real-world healthcare systems.

Prof David Curtis, an honorary professor at the UCL Genetics Institute, University College London, said: “Everybody over 50 could be routinely screened every few years, in much the same way as they are now screened for high cholesterol.

“It is possible that currently available treatments for Alzheimer’s disease would work better in those diagnosed early in this way. However, I think the real hope is that better treatments can also be developed. The combination of a simple screening test with an effective treatment for Alzheimer’s disease would have a dramatic impact for individuals and for society.”

The study from Dr Nicholas Ashton, of the University of Gothenburg, and colleagues is published in the Jama Neurology journal.