Blood test could predict dementia 15 years earlier than scans

A BLOOD test to predict dementia up to 15 years earlier than is possible now could help identify people who could benefit from new Alzheimer’s drugs.

Scientists have identified 11 proteins that will predict dementia in nine out of 10 cases. The drugs, donanemab and lecanemab, which slow the disease may soon be available. But only two per cent of patients would receive the medication because diagnosis is so poor.

The new test looks for proteins in the blood that occur when people have dementia and can pick up cases early when drugs will be most beneficial.

Prof Jianfeng Feng, of 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.”

More than 944,000 people in the UK have dementia, with the number expected to rise to more than a million by 2030.

In the study, which is thought to be the largest of its kind, researchers looked at data from more than 50,000 healthy people stored at UK Biobank, which holds medical records of more than half a million Britons.

They analysed the blood samples from this group collected between 2006 and 2010 and found 11 proteins in the 1,400 people who went on to develop dementia.

Dr Sheona Scales, director of research at Alzheimer’s Research UK, said: “New treatments like lecanemab will only be effective if they are given to people in their early stages of Alzheimer’s and at the moment very few people have access to the tests needed.

“Blood tests could unlock early diagnosis and are showing great promise, but so far, none have been validated for use in the UK.”

The new drugs, which are yet to be approved in Britain, can slow down the disease by around 24 to 30 per cent. But charities like Alzheimer’s Research are concerned that tens of thousands of patients could miss out because effectiveness depends on early diagnosis.

Estimates from the NHS suggest the drugs could cost £1 billion a year, with up to 280,000 people a year benefiting. But the paper from NHS England says health officials “should be cautious” about driving a massive expansion in such scans, as blood tests could replace the technology in the long term.

The paper suggests the drugs may offer “a limited clinical benefit” and carry “very significant costs”, even with extra government funding.

Sir John Hardy, professor of neurodegenerative diseases at University College London, told a BBC Panorama documentary: “There are only a few centres at the moment who could really give this drug effectively. We need to rethink dementia care in the UK. And that’s going to require quite a lot of reorganisation.”

Details of the new blood test were published in Nature Ageing.