Blood Tests Can Now Track Neurodegeneration Before Symptoms—NfL Has Emerged as the Universal Marker Across ALS, Alzheimer's, and Parkinson's

Crita· Mar 2, 2026

This infographic illustrates how Neurofilament light chain (NfL) leaks from dying neurons into the bloodstream years before symptoms, acting as a universal biomarker for early detection of neurodegenerative diseases. It highlights the potential for early intervention by tracking NfL levels and considering disease-specific markers.

Neurofilament light chain (NfL) is leaking into blood and cerebrospinal fluid years before clinical symptoms appear. This protein, released when neurons die, is becoming the closest thing we have to a universal biomarker for neurodegenerative disease progression.

The question now is whether we can use these markers to intervene earlier—and whether disease-specific signatures like p-tau217 for Alzheimer's or TDP-43 for ALS give us better predictive power than the general neuronal injury signal.