New blood test could help detect Alzheimer's disease

A new blood test could help doctors identify people who are likely to develop Alzheimer’s disease up to 20 years before the condition occurs.

Researchers at Washington University School of Medicine in St. Louis developed the test to detect early brain changes such as memory loss and confusion. The blood test is able to measure levels of the protein amyloid beta and predict whether it has accumulated in the brain. Amyloid beta builds up in the brain and can be an early indicator of Alzheimer’s.

The test is able to combine blood amyloid levels with two other major Alzheimer’s risk factors and identify a patient’s risk of the disease with 94% accuracy, the study found. It uses a technique called mass spectrometry to measure the amounts of two forms of amyloid beta in the blood: amyloid beta 40 and 42. The ratio of these forms goes down as the amount of amyloid beta deposits in the brain goes up.

The researchers originally struggled to achieve a clinically-accurate test and so incorporated several other Alzheimer’s risk factors to improve the test.  By incorporating age and a genetic variant called APOE4, the team was able to raise the accuracy of the test to 94%.

The researchers originally included gender as well but found it did not significantly affect the test’s analysis.

The blood test could help bring new drugs for Alzheimer’s to market by screening people with early signs of the disease so they can participate in clinical trials. Clinical trials currently struggle to identify participants who have Alzheimer’s brain changes but no cognitive problems.

The researchers said that while the test may be available clinically within a few years, its true benefits will be felt by helping bring about new treatments to halt the disease process and forestall dementia.

Importantly, the blood test may be more accurate than PET brain scans, the current gold-standard in detecting the beginnings of amyloid deposition in the brain. PET scans can cost upwards of $4,000 with blood tests costing a few hundred dollars each.

Senior author, Randall J. Bateman said: “If you want to screen an asymptomatic population for a prevention trial, you would have to screen, say, 10,000 people just to get 1,500 or 2,000 that would qualify. 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 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.”