Diagnosing Alzheimer’s disease can be a difficult and lengthy process, but within the next few years, this could change, thanks to one or more blood tests, suggest scientists.
Blood tests looking for signs of Alzheimer’s are already used in research – but aren’t routinely used by doctors in most countries – and now a project is testing their accuracy in real-world settings, which might result in them being used within five years.
New Scientist reports that the project to see which one works best has been launched by a coalition of UK medical research funders.
Those involved predict they will have at least one test ready to be routinely used when people consult a doctor for memory problems by the project’s end, in five years.
“We expect, then, that the pathway to getting a diagnosis will be completely different,” said Susan Kohlhaas from charity Alzheimer’s Research UK at the project’s launch last week.
The team can be so confident of the project’s success because the tests have been shown to have good accuracy when used in research, said Joanne Rodda from the Kent and Medway Medical School in Canterbury.
“These tests have an accuracy that is comparable to spinal fluid tests, which are currently used as part of the Alzheimer’s diagnosis process,” she said.
The tests used in research are usually based on the various forms of two proteins involved in Alzheimer’s. One – beta-amyloid – builds up outside brain cells. The other, tau, accumulates within the cells.
Several firms internationally offer testing for an Alzheimer’s-associated variant of each of these proteins to gauge whether someone may have the condition.
The tests need to be assessed under real-world conditions because, although Alzheimer’s can affect anyone, those with the condition who take part in clinical trials are often white and also have higher income levels than most of the population.
The results may also be affected by variations in diet or lifestyle.
The project to compare some of the different available tests, known as the Blood Biomarker Challenge, is being run jointly by the Alzheimer’s Society, Alzheimer’s Research UK and the UK’s National Institute for Health and Care Research.
The impetus partly stems from the development of treatments that clear amyloid from the brain. Two drugs consisting of antibodies that bind to amyloid slightly slow the deterioration seen with Alzheimer’s, although the effect is small and there are concerns about side effects.
One of them, called lecanemab, is approved in the US for treating Alzheimer’s, although to be eligible, people need to have a confirmed build-up of amyloid, usually from a positron emission tomography brain scan or a sample of spinal fluid, which could be avoided if a blood test accurately looked for raised levels of one of the amyloid variants.
It would also have other advantages, even before any new treatments become available, said Rodda.
People who see a doctor because of memory problems can take months or even years to get a diagnosis, with the process usually involving different kinds of cognitive tests and sometimes multiple brain scans.
A blood test probably wouldn’t avoid the need for cognitive tests, but would be done in addition to them, she said.
Rob Howard from University College London said a blood test would be a useful addition to existing diagnostic procedures, as it would help people gain faster access to some existing treatments of Alzheimer’s symptoms, like cholinesterase inhibitor drugs.
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