Alzheimer's blood test could boost research after successive trial failures

A blood test could be used to diagnose Alzheimer’s before symptoms arise, providing an alternative to expensive brain scans and speeding up recruitment to badly-needed clinical trials.

Scientists from the Washington University School of Medicine in St Louis decided to develop a blood test that could be administered quickly and at greater scale to the PET scans commonly used to detect the clumps of amyloid protein in the brain that are telltale signs of Alzheimer’s.

While first attempts were not quite as accurate as PET scans, the researchers found they could increase the accuracy by also looking at a patients’ age and the presence of the APOE4 gene variant.

Results were double-checked using a conventional PET scan, and accuracy of the test rose to 94% in a study involving 158 people.

The study used mass spectrometry to measure the ratio of amyloid beta 42 and amyloid beta 50 in the blood - a ratio known to drop when the amyloid deposits increase in the brain.

Results of the study published in the journal Neurology could be important for pharma companies looking for ways to intercept the disease and treat it before cognitive decline takes hold.

So far attempts have been unsuccessful, and there is a pressing need to identify patients early to help in future Alzheimer’s drug trials.

The study was widely reported in media outlets as experts highlighted its significance for Alzheimer’s research.

Randall Bateman, a professor of neurology at Washington University School of Medicine who led the study team, told the Guardian: “Right now we screen people for clinical trials with brain scans, which is time-consuming and expensive; 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.”

Pharma’s attempts to develop diseases that stop or slow the rate of cognitive decline, and trial after trial has turned up negative results.

The last drug approved by the FDA to treat Alzheimer’s was memantine in 2003, although an extended-release version was approved in 2014.

Earlier this year, Biogen's aducanumab became the latest Alzheimer's drug to fail in a big trial, wiping billions from the company's value.