The Washington University School of Medicine in St. Louis has reported that a new blood test was able to accurately identify the accumulation of amyloid beta, a protein associated with Alzheimer’s disease, in study participants.

Using mass spectrometry, the new test measures the blood levels of amyloid beta 42 and amyloid beta 40, which are known to decrease when the amount of amyloid beta deposits increases in the brain.

The study involved 158 volunteers aged 50 and over. With the exception of ten, all participants were cognitively normal, provided a blood sample, and received a PET brain scan at the current gold standard.

Analysis showed the blood test to be 88% accurate in detecting the amyloid compared to a PET scan.

To increase accuracy, the researchers combined the test with age and genetic testing for APOE4, which is said to raise the risk of developing the neurodegenerative disease by three to five-fold.

It was observed that when used with these risk factors, the blood test’s accuracy came up to 94%.

The researchers further analysed individuals who had mismatched results with the test and PET scan.

In some participants, false positives with the blood test were later found to be positive with subsequent brain scans at an average of four years later.

This could mean a blood test is more sensitive than a PET scan and is able to identify the risk of Alzheimer’s even before symptoms appear, said the researchers.

While the new test is years from clinical availability, it is expected to help in identifying participants for trials of drug candidates designed to halt disease progression in its early stages as well as prevent dementia.

Washington University School of Medicine in St. Louis neurology 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 enrol 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.”

When analysed in an Alzheimer’s prevention trial, the researchers observed that a blood test followed by a confirmatory PET scan would have cut down the number of scans, which cost nearly $4,000 each.