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Breakthrough blood test can spot signs of Alzheimer's 20 years before symptoms start

 

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Disease: Experts said the test raised ethical questions about telling someone they would later develop Alzheimer’s. PHOTO POSED

Disease: Experts said the test raised ethical questions about telling someone they would later develop Alzheimer’s. PHOTO POSED

Disease: Experts said the test raised ethical questions about telling someone they would later develop Alzheimer’s. PHOTO POSED

A simple blood test for Alzheimer's, capable of spotting the disease 20 years before memory loss and confusion occur, is on the horizon.

Scientists found that tiny fragments of a protein in the brain of people with dementia also starts to circulate in the blood early on in the illness.

The discovery opens the door to widespread screening and will enable doctors to detect the condition far earlier, when it may be possible to halt or reverse deterioration in the brain.

It will also be able to speed up trials into new drugs and tell someone they are unlikely to get the condition if they were concerned about memory loss.

Dr Rosa Sancho, of Alzheimer's Research UK, said: "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 with dementia."

Although there are currently no drugs or treatments, many experts believe preventing the onset of symptoms may be possible even if reversal is not.

Alzheimer's is linked to a rise in levels of amyloid plaques and tau tangles in the brain which stop cells communicating. Previously, it was only possible to detect their presence via brain scans or a spinal tap, which are expensive and invasive. The level of tau in spinal fluid was already known to predict the onset of cognitive symptoms but scientists were unsure if it could be seen in the blood.

Researchers at Washington University School of Medicine in St Louis developed a technique to detect minute amounts of tau in just 4ml of blood and found it correlated to dementia levels. Healthy people had tiny levels of tau.

The research, presented virtually at the Alzheimer's Association International Conference, was hailed as a major breakthrough by experts.

Clive Ballard, professor of age-related disease at University of Exeter Medical School, said: "This represents an exciting step toward developing a blood test that could help identify Alzheimer's by focusing on specific subtypes of tau.

"A lot of work will be needed to achieve standardisation of the test - so it could still be at least five years before we see an accurate blood biomarker test for dementia."

However, some experts raised concerns about the ethical implications of informing someone they were likely to develop Alzheimer's years before symptoms emerged, and particularly before a treatment was available.

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Prof David Curtis, of UCL Genetics Institute, said: "Do people want to know they will develop Alzheimer's, given there is no treatment? There may be difficult ethical issues to think about."

Telegraph Media Group Limited [2022]


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