Brain health
Neurofilament light
A marker of neuroaxonal injury.
What it measures
Neurofilament light released with axonal damage.
Why it matters
Useful in several neurological disease contexts and increasingly measurable in blood.
How to interpret it
Interpret by age, renal function, assay and neurological context.
Important limitations
Nonspecific for the cause of neuronal injury and not a general brain-aging score.
Evidence status
Clinical biomarker
Established or emerging clinical utility in defined neurological contexts; broader longevity screening is not established.
Research & guidance
Original papers, validation studies, reviews and clinical guidance connected to this measurement.
systematic review
Blood biomarkers for diagnosis and differential diagnosis of Alzheimer's disease in real-world clinical populations: A systematic review
Alzheimer's & Dementia · 2026
NfL is a nonspecific neuronal-injury marker with variable diagnostic performance for Alzheimer disease.
prospective cohort
Blood-based biomarkers of Alzheimer's disease and incident dementia in the community
Nature Medicine · 2025
Community cohort evidence associates NfL with future dementia risk, but it is not disease-specific.
For education and evidence exploration, not diagnosis or individualized medical advice.