Skip to content

Blood Protein Levels Could Help Predict Alzheimer's Disease

Leakage from brain can be a sign of the disease long before cognitive symptoms emerge

A stethoscope and blood vials.

Science Photo Library/Alamy

En español | A simple blood test for a protein identified with Alzheimer’s disease could help identify those who have the illness in its earliest stages, well before apparent signs of it emerge, although the protein is also identified with other neurological issues.

Key to the test is the presence of the neurofilament light chain protein (NfL). It is contained in neurons in the brain. But damaged cells leak NfL, which ultimately enters the bloodstream. Researchers say detection of NfL in the blood could be made years before symptoms like memory loss or confusion are seen in Alzheimer’s patients.

Researchers from Washington University in St. Louis and the German Center for Neurodegenerative Diseases published a letter on their study in a recent issue of the medical journal Nature Medicine.

For their study, researchers relied on families that may carry a rare inherited genetic variant that can cause Alzheimer’s earlier than average, when people are in their 40s or 50s. The researchers studied more than 400 people from such families, of whom 247 carried the variant. In those with the mutation, levels of NfL in the blood were high at the start of the research and rose over time. Among those who didn’t carry the variant, the protein level was low and stayed that way.

The difference in such levels can be detected 16 years “before cognitive symptoms [of Alzheimer’s] were expected to arise,” the researchers found.

But leakage of the protein is linked to other neurological diseases as well as physical trauma.

“Protein levels are high in people with Lewy body dementia and Huntington’s disease,” the Washington University School of Medicine reported. “They rise dramatically in people with multiple sclerosis during a flare-up and in football players immediately after a blow to the head.”