Blood test could detect Alzheimer's years before symptoms appear

Research suggests seeds of disease are planted many years before symptoms appear

This illustration made available by the National Institute on Aging/National Institutes of Health depicts cells in an Alzheimer’s affected brain, with abnormal levels of the beta-amyloid protein clumping together to form plaques, brown, that collect between neurons and disrupt cell function. Abnormal collections of the tau protein accumulate and form tangles, blue, within neurons, harming synaptic communication between nerve cells. An experimental Alzheimer’s drug modestly slowed the brain disease’s inevitable worsening, researchers reported Tuesday, Nov. 29, 2022 - and the next question is how much difference that might make in people’s lives. Japanese drugmaker Eisai and its U. S. partner Biogen had announced earlier this fall that the drug lecanemab appeared to work, a badly needed bright spot after repeated disappointments in the quest for better Alzheimer’s treatments. (National Institute on Aging, NIH via AP)Show less

Toxic protein shown in a blood test could detect Alzheimer’s disease years before symptoms appear, a study suggests.

Patients tend to receive a diagnosis of Alzheimer’s only after they show well-known signs of the disease, such as memory loss.

At this point the best treatment options simply slow further progression of symptoms, experts say.

But research suggests the seeds of the disease are planted many years before the symptoms that make diagnosis possible.

These seeds are called amyloid beta proteins, which fold and clump together and form something called oligomers.

Over time toxic oligomers are thought to develop into Alzheimer’s, although scientists are still trying to understand the process through which this happens.

New drug appears to improve Alzheimer’s - in pictures

• 

  A clinical trial of the drug lecanemab shows it may slow down Alzheimer’s in the early stages. Experts have described it as a breakthrough in tackling the disease. PA

• 

  A close-up of a human brain affected by Alzheimer's. Japanese company Eisai and its US partner Biogen developed the drug. AP

• 

  An illustration of how Alzheimer’s affects the brain, with abnormal levels of the beta-amyloid protein clumping together to form plaques – brown in this rendering – that collect between neurons and disrupt cell function. Photo: National Institute on Ageing

• 

  Sajid Javid, who served as UK health secretary, said Britain's 10-year plan to tackle dementia has a focus on prevention. Photo: Alzheimer's Society

• 

  A US advert aimed at loosening proposed restrictions on new Alzheimer's treatments. Photo: Reuters

Researchers at the University of Washington developed a laboratory test that can measure levels of amyloid beta oligomers in blood samples.

The study suggests their test — known by the acronym Soba — could detect oligomers in the blood of patients with Alzheimer’s, but not in most members of a healthy trial group who showed no signs of cognitive impairment at the time the blood samples were taken.

However, the study says the test was able to detect oligomers in the blood of 11 people from the non-Alzheimer’s group.

When researchers looked at follow-up records for 10 of these people, all of them were diagnosed years later with mild cognitive impairment or brain pathology consistent with Alzheimer’s disease.

How a three-minute iPad test could diagnose dementia - video

Essentially, for these 10 people, the Soba detected the toxic oligomers before symptoms surfaced, the scientists say.

“We believe that Soba could aid in identifying individuals at risk or incubating the disease, as well as serve as a readout of therapeutic efficacy to aid in development of early treatments for Alzheimer’s disease,” said senior author Valerie Daggett, a professor at the University of Washington.

“What clinicians and researchers have wanted is a reliable diagnostic test for Alzheimer’s disease, and not just an assay that confirms a diagnosis of Alzheimer’s, but one that can also detect signs of the disease before cognitive impairment happens.

“That’s important for individuals’ health and for all the research into how toxic oligomers of amyloid beta go on and cause the damage that they do.

“What we show here is that Soba may be the basis of such a test.”

iPad test dementia - in pictures

• 

  Dr Sina Habibi has developed a rapid iPad AI test that can detect early signs of dementia. All photos: Chris Whiteoak / The National

• 

  Dr Habibi says thousands of people have already completed successful trials in South London and Maudsley NHS trusts.

• 

  He says a rapid screen test on the iPad checks the speed and accuracy of a person's thinking by asking them to select pictures with animals from a series of images.

• 

  The Integrated Cognitive Assessment test delivers a score out of 100 to test if someone is healthy, at risk or impaired.

• 

  Response accuracy can be measured to assess healthy brain function, allowing doctors to prescribe relevant steps to delay the potential onset of dementia as we age.

• 

  Dr Habibi says the programme is in the trail stage and thousands have taken it the UK.

Soba, which stands for soluble oligomer binding assay, exploits a unique property of the toxic oligomers, researchers say.

When misfolded amyloid beta proteins begin to clump into oligomers, they form a structure known as an alpha sheet, which tends to stick to other alpha sheets, research suggests.

The Soba test features a synthetic alpha sheet that can bind to those detected in blood samples.

The test then uses standard methods to confirm that the oligomers attached to the test surface are made up of amyloid beta proteins.

The team tested Soba on blood samples from 310 research subjects who had previously made their blood samples and some of their medical records available for Alzheimer’s research.

They detected oligomers in the blood of people with mild cognitive impairment and moderate-to-severe Alzheimer’s.

The findings are published in the Proceedings of the National Academy of Sciences.