Detecting Alzheimer’s years before symptoms with blood test

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A new study claims that a simple blood test can reliably detect signs of brain damage in people on the path to developing Alzheimer’s disease years before memory loss occurs.

Published in Nature Medicine, the findings from the Washington University School of Medicine in St. Louis and the German Centre for Neurodegenerative Diseases in Germany may one day be applied to quickly and inexpensively identify brain damage in people with not just Alzheimer’s disease but other neurodegenerative conditions such as multiple sclerosis, traumatic brain injury or stroke.

“This is something that would be easy to incorporate into a screening test in a neurology clinic,” said Brian Gordon, an assistant professor of radiology at Washington University’s Mallinckrodt Institute of Radiology and an author on the study. 

“We validated it in people with Alzheimer’s disease because we know their brains undergo lots of neurodegeneration, but this marker isn’t specific for Alzheimer’s. High levels could be a sign of many different neurological diseases and injuries.”

The test detects neurofilament light chain, a structural protein that forms part of the internal skeleton of neurons. When brain neurons are damaged or dying, the protein leaks out into the cerebrospinal fluid that bathes the brain and spinal cord and from there, into the bloodstream.

“Sixteen years before symptoms arise is really quite early in the disease process, but we were able to see differences even then,” said Washington University graduate student Stephanie Schultz, one of the paper’s co-first authors.

“This could be a good preclinical biomarker to identify those who will go on to develop clinical symptoms.”

“It will be important to confirm our findings in late-onset Alzheimer´s disease and to define the time period over which neurofilament changes have to be assessed for optimal clinical predictability,” said Jucker, who leads the DIAN study in Germany.

A commercial kit – very similar to the one used by the authors – is available to test for protein levels in the blood, but it has not been approved by the FDA to diagnose or predict an individual’s risk of brain damage.

Before such a test can be used for individual patients with Alzheimer’s or any other neurodegenerative condition, researchers will need to determine how much protein in the blood is too much, and how quickly protein levels can rise before it becomes a cause for concern.

“I could see this being used in the clinic in a few years to identify signs of brain damage in individual patients,” said Gordon, who is also an assistant professor of psychological & brain sciences.

“We’re not at the point we can tell people, ‘In five years you’ll have dementia.’ We are all working towards that.”