With aging populations on the rise, the need for better tools to diagnose and monitor Alzheimer’s disease (AD), the most common cause of dementia, has never been more urgent. This disease is characterized by the gradual loss of nerve cells, a process known as neurodegeneration, which begins years before the onset of obvious symptoms. One way to detect this damage is to look for signs of injury to nerve cells.

A key emerging biomarker of neurodegeneration is neurofilament light chain (NfL), a structural protein component of large nerve fibers. When neurons are injured, NfL escapes into the cerebrospinal fluid and eventually into the bloodstream, providing a window into ongoing neurodegeneration.