Simple blood test to detect Alzheimer’s disease 20 years before symptoms show

It would be cheap and painless to roll out in stark contrast to current diagnostic methods, which are typically not used until symptoms are well advanced. Crucially the test could enable experts to track the stages of dementia, allowing earlier and more accurate diagnoses. The breakthrough came after scientists found a way to test for a raised protein in the bloodstream which distinguishes Alzheimer’s from other neurodegenerative disorders with a diagnostic accuracy of between 89 and 98 percent.

The findings were presented at the annual Alzheimer’s Association International Conference. Prof John Hardy, of University College London, said: “Over the last five years the possibility of using [blood-based tests] to aid in the diagnosis and assessment of Alzheimer’s versus other causes of dementia has improved enormously and these well-performed studies are a further step in that process – blood-based markers of disease and disease progression are now a reality and this will help with drug trial assessment and clinical practice.”

Scientists from Lund University in Sweden, Banner Alzheimer’s Institute in the US, and pharmaceutical giant Eli Lilly were able to pick out the changes in brain proteins known as amyloid and tau which are hallmarks of Alzheimer’s.

Their findings were based on tests on more than 1,400 people using blood and cerebrospinal fluid, as well as imaging.

Prof Clive Ballard, of the University of Exeter Medical School, said: “This research represents an exciting step towards developing a blood test that could help identify Alzheimer’s by focusing on specific subtypes of tau, one of the key proteins that becomes abnormal as part of the disease changes in the brain. The findings come from a top research group and this is an encouraging and robust development.”

Rosa Sancho of Alzheimer’s Research UK said: “Currently people only receive an Alzheimer’s diagnosis once symptoms appear.

“Many of the diagnostic tools that can detect early changes are expensive, like brain scans, or invasive such as spinal fluid tests.

“A reliable blood test for Alzheimer’s would be a huge boost for dementia research, allowing scientists to test treatments at a much earlier stage which in turn could lead to a breakthrough for those living with dementia.”

Dr Fiona Carragher, of Alzheimer’s Society, said: “A cost-effective, accurate and non-invasive diagnostic test is a vital step in developing new treatments for the 850,000 people living with dementia in the UK today.

“Excitingly, this blood test for tau appears to not only show signs of being able to accurately distinguish between Alzheimer’s disease and other neurodegenerative conditions, but also may detect changes before symptoms even appear.”

Lead researcher Oskar Hansson, said: “This test, once verified and confirmed, opens the possibility of early diagnosis of Alzheimer’s before the dementia stage, which is very important for clinical trials evaluating therapies that might stop or slow down the disease process.”

Comment by Kate Lee

This has the potential to be a really exciting discovery, as this diagnostic test may be able to detect changes in the brain before symptoms of Alzheimer’s disease appear.

Progress in developing a blood test has moved rapidly in recent years and this marks an important further step.

Currently, the brain changes that occur before symptoms appear can only be assessed by measuring proteins in spinal fluid and PET scans, which are invasive, expensive, and often hard to access.

Not only is this diagnostic test cost-effective, accurate and non-invasive, but it may also be able to reflect changes taking place in the brain.

Additionally, it’s showing signs of being able to accurately distinguish between Alzheimer’s disease and other neuro-degenerative conditions.

Though currently in its early stages, it is incredibly important that this research has been carried out in a diverse population, and we’re eager to see what future research into tests like this could do to revolutionise the way we detect dementia. By 2025 there will be a million people with dementia, so we need to explore every avenue in the detection and treatment of this condition.

Despite this, the coronavirus pandemic has caused an expected 40 percent average fall in investment this year across medical research charities, which has a knock-on effect for the dementia research field.

If this research is validated, with larger and longer studies, a blood test of this nature could accelerate our ability to develop new treatments for Alzheimer’s.

This could also be a real game-changer to the family and friends of those in the early stages of Alzheimer’s, allowing them time to assess plans for the future as well as treatment options.

Kate Lee is the chief executive of the Alzheimer’s Society

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