An experimental blood test can accurately diagnose Alzheimer’s disease, the most common form of dementia, according to a study published Monday in the journal Proceedings of the National Academy of Sciences. Though still in development, the test may someday be used to diagnose other degenerative brain disorders and even mild cognitive impairment resulting from head injuries.
The researchers say that using the test, they were able to identify Alzheimer’s patients with up to 86% sensitivity and specificity. (Sensitivity refers true positives identified by the test, while specificity refers to true negatives.) The test also differentiated Alzheimer’s from dementia with Lewy bodies, a related condition, with 90% sensitivity and specificity.
The new test’s “accuracy is markedly higher than other tests being developed,” said senior study author Francis Martin, a professor in the School of Pharmacy and Biomedical Sciences at the University of Central Lancashire in the United Kingdom. “For such a simple test to be so predictive is very exciting.”
That said, he himself was surprised by the accuracy, given that other researchers have not achieved similar results using more sophisticated approaches, Martin wrote in an email.
Today, there’s only one conclusive test for Alzheimer’s diagnosis: a postmortem examination of a patient’s brain. Yet while a patient is alive, doctors diagnose the disease based on a careful evaluation that includes brain scans and in-depth mental testing, according to the website for the Alzheimer’s Society, a registered UK charity that funds research.
“Current methods of diagnosing dementia can be slow and expensive, so finding a cheap, quick test that can accurately identify if someone has dementia is a top priority for researchers,” said Doug Brown, director of research and development at Alzheimer’s Society. The society did not fund the new study, and Brown did not participate as a researcher.
A diagnosis of dementia is life-changing. With early detection, medical interventions have the best chance of slowing the progress of disease, according to the society.