New Alzheimer’s blood test could diagnose disease before symptoms show

Scientists hope test will identify more patients for trials of dementia-preventing treatment

Blood tests can pick up dementia-causing protein build-ups in the brain before symptoms appear
Blood tests can pick up dementia-causing protein build-ups in the brain before symptoms appear

A blood test to identify the early stages of Alzheimer’s disease has been developed by scientists in what could prove to be a major breakthrough in the treatment of the condition.

Researchers say the simple test for the neurodegenerative disease, which has been found to be more than 90 per cent accurate, could be available at GP surgeries “within a few years”.

However, its benefits may be greater once there are treatments to halt Alzheimer’s or prevent its onset entirely.

Up to two decades before people develop the characteristic memory loss and confusion caused by the disease, damaging clumps of protein start to build up in their brains.

Researchers at Washington University School of Medicine in the US said that they can measure levels of the Alzheimer’s protein amyloid beta in the blood and use such levels to predict whether the protein has accumulated in the brain.

When blood amyloid levels are combined with two other major dementias risk factors – age and the presence of the genetic variant APOE4 – people with early Alzheimer’s brain changes can be identified with 94 per cent accuracy.

The research team said that the findings, published in the journal Neurology, represent another step towards a blood test to identify people likely to develop Alzheimer’s before symptoms arise.

Researchers believe the test may be even more sensitive than the “gold standard” – a PET brain scan – at detecting the beginnings of amyloid deposition in the brain.

Scientists say clinical trials of preventive drug candidates have been hampered by the difficulty of identifying participants who have Alzheimer’s brain changes but no cognitive problems.

The blood test could provide a way to effectively screen for people with early signs of disease so they can participate in clinical trials evaluating whether drugs can prevent the disease.

Study senior author, Professor Randall Bateman, said: “Right now we screen people for clinical trials with brain scans, which is time-consuming and expensive, and enrolling participants takes years.

“But with a blood test, we could potentially screen thousands of people a month.

“That means we can more efficiently enroll participants in clinical trials, which will help us find treatments faster, and could have an enormous impact on the cost of the disease as well as the human suffering that goes with it.”

The study involved 158 adults over the age of 50. All but 10 of the participants were cognitively normal, and each provided at least one blood sample and underwent one PET brain scan.

Researchers classified each blood sample and PET scan as amyloid positive or negative, and found that the blood test from each participant agreed with his or her PET scan 88 per cent of the time.

To improve the test’s accuracy, the researchers incorporated a number of major risk factors for Alzheimer’s, including age and the presence of a genetic variant called APOE4.

When the researchers included age and APOE4 status the accuracy of the blood test rose to 94 per cent.

Prof Bateman added: “Reducing the number of PET scans could enable us to conduct twice as many clinical trials for the same amount of time and money.

“It’s not the $4,000 (£3,300) per PET scan that we’re worried about. It’s the millions of patients that are suffering while we don’t have a treatment. If we can run these trials faster, that will get us closer to ending this disease.”

Additional reporting by SWNS

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