01/27/2026
Neurofilament light chain (NfL) is a strong predictor of dementia risk and cognitive decline as a result of a brain injury, with elevated levels in both CSF and blood associated with increased risk of progression from normal cognition to mild cognitive impairment (MCI) or dementia.
NfL levels can remain elevated for over a decade in individuals at risk for dementia, beginning in the presymptomatic phase and continuing through clinical progression. In sporadic Alzheimer's disease, plasma NfL levels begin diverging from controls approximately 9.6 years before clinical diagnosis and continue rising throughout the disease course.
Testing for NfL can shed light on your recovery from your head trauma, even when asymptomatic.
The duration of elevation correlates with disease severity and progression rate—individuals with faster cognitive decline show steeper NfL increases over time. In population-based cohorts, peripheral GFAP and NfL elevations can be detected up to 15 years before dementia diagnosis.
Singh, R. K., Bekena, S., Damera, N., Zhu, Y., Trani, J. F., & Babulal, G. M. (2025). The relationships between cerebrospinal fluid neurofilament light chain and hippocampal atrophy with cognitive decline. Journal of Alzheimer's disease : JAD, 107(3), 1143–1153. https://doi.org/10.1177/13872877251365219
de Wolf, F., Ghanbari, M., Licher, S., McRae-McKee, K., Gras, L., Weverling, G. J., Wermeling, P., Sedaghat, S., Ikram, M. K., Waziry, R., Koudstaal, W., Klap, J., Kostense, S., Hofman, A., Anderson, R., Goudsmit, J., & Ikram, M. A. (2020). Plasma tau, neurofilament light chain and amyloid-β levels and risk of dementia; a population-based cohort study. Brain : a journal of neurology, 143(4), 1220–1232. https://doi.org/10.1093/brain/awaa054
Lehmann, S., Schraen-Maschke, S., Vidal, J. S., Blanc, F., Paquet, C., Allinquant, B., Bombois, S., Gabelle, A., Delaby, C., Hanon, O., & BALTAZAR Study Group (2023). Blood Neurofilament Levels Predict Cognitive Decline across the Alzheimer's Disease Continuum. International journal of molecular sciences, 24(24), 17361. https://doi.org/10.3390/ijms242417361