Blood Test Detects Alzheimers Twenty Years Before Symptoms Appear

A study undertaken by researchers from the Washington University School of Medicine (WUSTL) has found that a blood test can identify the protein that accumulates in the brains of people with Alzheimer’s almost two decades before the symptoms appear. The study discovered that the blood test was even more sensitive at identifying the build-up of beta-amyloid proteins in the brain than the existing gold standard, which is a PET brain scan. First author Dr.Suzanne Schindler, Assistant Professor, Neurology, developed a version of the test a few years ago. The findings of the team, led by Schindler, have been published in the journal Neurology.

The test employs a mass spectrometry on blood samples to detect the concentration of two forms of the beta-amyloid protein viz., beta-amyloid 42 and beta-amyloid 40. The beta-amyloid that accumulates in the brain causes the ratio between the two proteins to drop, which appears in the blood test. The team examined 15 adults, above the age of 50 years, and all but 10 exhibited normal cognitive function. For the study, each person was subjected to a blood test and a PET brain scan. The team categorized each test as either amyloid positive or amyloid negative, and in 88% of the cases, the results were in agreement with each other. The researchers wanted to see if they could refine the results to improve the accuracy of the blood test. They looked at significant risk factors linked with Alzheimer’s, such as age, biological sex, and a particular genetic variant. The age and specific genetic variant were found to have an impact on the accuracy of the results, able to significantly improve it.

When the team considered the age and genetic variant and the results from the blood test, they recorded that the accuracy had escalated by 94%. In the follow-up performed after a few years, the researchers found that some individuals tested positive in succeeding brain scans. The team’s findings indicate that some early blood tests were more sensitive than the brain scans in identifying the disease in its initial stages.