A blood test that can detect signs of Alzheimer’s as much as 20 years before the disease begins to have a debilitating effect has been developed by researchers in the US. Scientists at the Washington University School of Medicine in St Louis in Missouri believe the test can identify changes in the brain suggestive of Alzheimer’s with 94% accuracy while being much cheaper and simpler than a PET brain scan. The results of the study, which was published in the journal Neurology on Thursday, represent a potential breakthrough in the fight against the disease. “Right now we screen people for clinical trials with brain scans, which is time-consuming and expensive, and enrolling participants takes years,” said the senior author, Randall Bateman, a leading professor of neurology. “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.”
The researchers said they had found a way to measure levels of the protein amyloid-beta, a key indicator of Alzheimer’s, in the blood. They can then use such levels to predict whether the protein has accumulated in the brain. That analysis could then be combined with two other major Alzheimer’s risk factors – age and the presence of the genetic variant APOE4 – to accurately identify the relevant changes in the brain. The researchers said the clumps of protein begin to form in the brain up to two decades before the onset of the characteristic memory loss, suggesting the tests could be used to predict Alzheimer’s years in advance. However, the benefits of such testing would not be seen to their fullest extent until treatments to halt the disease are developed. In January 2018, a team of scientists revealed their work on a test that used mass spectrometry techniques to identify patients with a rogue peptide in their blood plasma, indicating a build-up of beta-amyloid in the brain. The latest study looked at 158 people aged older than 50. All but 10 of the participants in the new study were cognitively normal and each provided at least one blood sample and underwent one PET brain scan. The researchers found that the blood tests gave the same results as the PET scans 88% of the time, which was not satisfactory. In order to improve the accuracy, the scientists began incorporating the other risk factors, increasing the accuracy to more than 90%.
Credit: Kevin Rawlinson for The Guardian, 2 August 2019.