New blood test checks for Alzheimer's and assesses progression, study says

The Guardian

31-03-2025

Researchers have developed a blood test for patients with thinking and memory problems to check if they have Alzheimer's and to see how far it has progressed.
The team behind the work say the test could help medics decide which drugs would be most suitable for patients. For example, new drugs such as donanemab and lecanemab can help slow the progression of Alzheimer's, but only in people in the early stages of the disease.
Prof Oskar Hansson from Lund University, a co-author of the work, said: 'There is an urgent need for accurate and cost-effective Alzheimer diagnostics considering that many countries have recently approved the clinical use of amyloid-targeted therapies [such as donanemab and lecanemab].'
Plaques of a protein called amyloid beta and the formation of tangles of another protein called tau in the brain are considered hallmarks of Alzheimer's disease.
Writing in the journal Nature Medicine, Hansson and colleagues reported how they found fragments of tau, called eMTBR-tau243, could be detected in blood and correlated with a build-up of tau tangles in the brains of people with Alzheimer's, but not other diseases.
The team's analyses, which involved 902 participants, found levels of this tau fragment were elevated in people with Alzheimer's symptoms who had mild cognitive impairment, and higher again in those with dementia. Levels were not raised in people with cognitive impairments due to other conditions.
'Scientifically, these results are very promising and important as this marker performed better than existing tests and the new marker could help track performance of new drugs in trials,' said Prof Tara Spires-Jones, a neurodegeneration expert at the University of Edinburgh who was not involved in the work.
But, she said, it was not a foolproof blood test for Alzheimer's.
'This is also not a simple test, rather requiring complex scientific methods only available in specialist laboratories, so this will not be routinely available without further validation and development of cheaper, easier detection,' she said.
Dr Sheona Scales, the head of research at Alzheimer's Research UK, said eMTBR-tau243 was one of a number of different biomarkers being studied for use in blood tests for Alzheimer's.
'What's interesting is that the blood levels of eMTBR-tau243 seem to be linked to a person's memory and thinking abilities,' she said. 'At present, it is not always possible to make a connection between the level of tangles observed with imaging and level of cognitive impairment, but having blood tests that do this will help to monitor diseases like Alzheimer's in the brain as they progress, and help inform prognosis in future.'
Another piece of research, also published in Nature Medicine, has revealed the ratio of two proteins in brain fluid is associated with the degree of cognitive impairment experienced by people with Alzheimer's, independent of levels of amyloid beta plaques and tau tangles in their brains.
This research, led by scientists in the US, involved samples from 3,397 people across the US, Sweden and Finland, and looked at levels of two proteins – YWHAG and NPTX2 – that are normally found at the junctions, or synapses, between neurons in the brain.
The team found the ratio of YWHAG:NPTX2 was better able to indicate that people were experiencing cognitive problems than their levels of amyloid beta and tau, and could be used to predict their future cognitive decline and dementia onset.
Prof Tony Wyss-Coray, a co-author of the study from Stanford University, said the results could help identify the best medications for individuals and help design better clinical trials by selecting appropriate participants.