Latest developments towards Alzheimer’s blood tests

Posted on 16th July 2019

Three new studies presented at the Alzheimer’s Association International Conference (AAIC) 2019 in Los Angeles today (Monday 15 July) shed light on the progress towards developing blood-based tests for the diseases that cause dementia.

An amyloid-based blood test for Alzheimer’s disease

Following from their previous research findings published in Nature in 2018, Japanese researchers looked at 201 blood samples from people from across Japan.

There are several different forms of the amyloid – the hallmark Alzheimer’s protein – some more sticky and harmful than others.

In this study, the team looked at the levels of different forms of amyloid in blood samples from people with Alzheimer’s disease, mild cognitive impairment and those without memory problems.

They compared the levels of amyloid present in the blood to brain changes measured by expensive PET brain scans. The team also compared the levels of amyloid in the blood to people’s scores on a memory test.

They found the levels of amyloid measured in the blood could predict the amount of amyloid in the brain, and other brain changes associated with Alzheimer’s, before symptoms of dementia, like memory loss, start to show.

Dr Carol Routledge, Director of Research at Alzheimer’s Research UK, said:

“We know that Alzheimer’s brain changes can begin decades before dementia symptoms start to show. These very early stages are likely to be the time when future drugs would be most effective.

“At the moment we can only diagnose Alzheimer’s when symptoms appear. PET brain scans can provide some warning signs of early disease, but these are very expensive and require specialist, high-tech facilities.

“This study raises the possibility of a straight-forward and cost-effective method for identifying people with early Alzheimer’s brain changes. A reliable blood test would be a huge boost for drug trials, allowing researchers to test potential medicines at an earlier stage when they are likely to be most effective.

“While we are yet to see the full findings from this research, much more testing and refinement will likely be necessary before a test like this could be used to support doctors making a diagnosis in the clinic.”

Using Neurofilament light chain to identify multiple diseases that cause dementia

Neurofilament light chain (Nfl) is a structural component of nerve cells in the brain. It leaks from the brain when these nerve cells become damaged and can end up in the bloodstream and spinal fluid.

In this study, presented by Dr Abdul Hye from King’s College London, the researchers looked to see whether levels of Nfl in the blood could distinguish several different diseases that cause dementia.

Working with two sets of volunteers from Kings College London and Lund University in Sweden, the researchers found levels of Nfl in the blood could distinguish eight different neurodegenerative diseases compared to healthy controls. The diseases included Alzheimer’s, frontotemporal dementia, dementia with Lewy bodies and motor neurone disease.

Dr Carol Routledge, Director of Research at Alzheimer’s Research UK, said:

“Neurofilament light chain protein is the most reliable biological indicator of ongoing damage in the brain. At the moment researchers analyse levels of the protein in spinal fluid that they have to collect through a lumbar puncture, but a blood test would be a much simpler procedure.

“Measuring neurofilament light chain in blood holds real potential as an effective test for suspected brain damage, but it can’t tell us the underlying cause. At Alzheimer’s Research UK we are exploring multiple different ways to detect specific diseases that cause dementia, and to drive progress towards more reliable and timely diagnosis.”

Alpha synuclein test for Alzheimer’s

Although Alzheimer’s disease has classically been characterised by a build-up of amyloid and tau in the brain, a protein called alpha-synuclein is also found at high levels in the disease.

Alpha-synuclein is also the protein implicated in dementia with Lewy bodies (DLB), which is the third most common cause of dementia.

In this study, Italian researchers looked at 39 people with early-stage Alzheimer’s and 39 healthy volunteers. They analysed levels of alpha-synuclein present in red blood cells alongside the levels of the amyloid and tau proteins.

The findings show that people with Alzheimer’s had much lower levels of alpha-synuclein combined with amyloid and tau in their red blood cells, compared to healthy volunteers.

Dr Carol Routledge, Director of Research at Alzheimer’s Research UK, said:

“The amyloid and tau proteins are the main biological hallmarks of Alzheimer’s and have been the major focus of researchers working on blood tests for the disease. Alpha synuclein plays a major role in Parkinson’s disease, but this research suggests that analysing levels of this protein in the blood could help to identify people with Alzheimer’s.

“The findings presented from this small study show an interesting trend but need to be investigated further. Future research must look at whether it can discriminate between Alzheimer’s, Parkinson’s and other related conditions and whether its level of accuracy can be improved.”

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