New dementia blood test can identify those at risk of losing their memory with 89% accuracy – years before symptoms

Home / Diagnostic / New dementia blood test can identify those at risk of losing their memory with 89% accuracy – years before symptoms
July 25, 2017July 25, 2017
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  • Decades before it strikes, sticky plaques can be seen in the brains of sufferers
  • Currently, the only way to detect amyloid beta is through costly procedures
  • But a study suggests blood tests, a much cheaper method, are just as accurate
  • Experts have described the Washington University findings as ‘exciting

A quick and affordable blood test to identify those at risk of dementia years before symptoms start has come a ‘significant step’ nearer.

Decades before the disease strikes and triggers memory loss, the brains of sufferers become dotted with sticky plaques.

Currently, the only way to detect the toxic substance, called amyloid beta, is through costly PET scanning or invasive spinal tap procedures.

But a new study suggests measuring for levels of the toxic protein in the blood has the potential to identify those at most risk with 89 per cent accuracy.

Senior author Professor Randall Bateman, of Washington University School of Medicine, described the findings as ‘exciting’.

Measuring for levels of the toxic protein, which has long been touted as a cause of dementia, in the blood has the potential to identify those at most risk, experts say

Measuring for levels of the toxic protein, which has long been touted as a cause of dementia, in the blood has the potential to identify those at most risk, experts say

‘This is exciting’ 

He said: ‘Our results demonstrate that this amyloid beta blood test can detect if amyloid has begun accumulating in the brain.

‘This is exciting because it could be the basis for a rapid and inexpensive blood screening test to identify people at high risk of developing Alzheimer’s disease.’

While the exact cause of Alzheimer’s disease remains elusive, amyloid beta has long been touted as a potential trigger, alongside tau protein.

The researchers are currently developing a test for the latter toxic substance that mimics that of the amyloid one.

‘A huge step forward’

Professor Bateman added: ‘If we had a blood test for tau as well, we could combine them to get an even better idea of who is most at risk of developing Alzheimer’s disease.

‘That would be a huge step forward in our ability to predict, and maybe even prevent, Alzheimer’s disease.’

As the brain engages in daily tasks, it continually produces and clears away amyloid beta – which can stop brain cells functioning properly.

Some is washed into the blood, and some floats in the cerebrospinal fluid, which is why spinal taps are used.

Decades before the disease strikes and triggers memory loss, the brains of sufferers become dotted with sticky amyloid beta plaque

Decades before the disease strikes and triggers memory loss, the brains of sufferers become dotted with sticky amyloid beta plaque

If the protein starts building up, it can collect into plaques that stick to neurons, triggering permanent damage.

Inconclusive trials 

Previous trials of amyloid beta blood tests have been inconclusive, but the latest study provides the clearest evidence to date of them being successful.

VIKING DIET TO FIGHT OFF DEMENTIA

Vikings may be best known for marauding and pillaging but there is one Nordic behaviour that is worth copying.

Sticking to a traditional Nordic diet can support brain health in old age and could help fight off dementia, Swedish researchers claimed earlier this week.

The diet is high in fish, non-root vegetables, fruit, rice and chicken, washed down with plenty of water and tea.

In good news for drinkers, the diet also includes a light to moderate consumption of wine.

People sticking to the so-called ‘healthy Nordic diet’ should avoid eating too many root vegetables, potatoes, refined grains, butter, sugar and fruit juice.

Researchers analysed blood levels of three amyloid subtypes, amyloid beta 38, 40 and 42, in each of the 41 volunteers over the age of 60.

Each person had 20 samples taken over a 24-hour period to measure levels of the protein, production and clearance.

Deposited into the blood 

They found that levels of amyloid beta 42 were consistently 10 to 15 per cent lower in those with amyloid plaques.

Professor Bateman said plaques are composed mainly of amyloid beta 42, meaning it is probably being deposited in the brain before moving into the blood.

He added: ‘The differences are not big, but they are highly consistent.

‘Our method is very sensitive, and particularly when you have many repeated samples as in this study – more than 500 samples overall – we can be highly confident that the difference is real.

‘Even a single sample can distinguish who has amyloid plaques.’

How accurate was it? 

By averaging the ratio of amyloid beta 42 to amyloid beta 40 over each person’s 20 samples, the researchers could classify people accurately as amyloid-positive or -negative 89 per cent of the time.

On average, any single time point was also about 86 per cent accurate, according to the study published in Alzheimer’s and Dementia.

Dr James Pickett, head of research at Alzheimer’s Society said: ‘This small study suggests a blood test for this purpose may not be that far away, but needs more validation.’

The findings were announced at the Alzheimer’s Association International Conference in London.