Clinical Application of Plasma Neurofilament Light Chain in a Memory Clinic: A Pilot Study.

Background And Purpose: Neurofilament light chain (NfL) has been considered as a biomarker for neurodegenerative diseases including Alzheimer's disease (AD). We measured plasma NfL levels in older adults with cognitive complaints and evaluated their clinical usefulness in AD.

Methods: Plasma levels of NfL, measured by using the single molecule array method, were acquired in a total of 113 subjects consisting of subjective cognitive decline (SCD; n=14), mild cognitive impairment (MCI; n=37), or dementia of Alzheimer type (DAT; n=62). Plasma NfL level was compared among three groups, and its association with cognitive and functional status was also analyzed.

Results: After adjusting for age, plasma NfL level was higher in subjects with DAT (65.98±84.96 pg/mL), compared to in subjects with SCD (16.90±2.54 pg/mL) or MCI (25.53±10.42 pg/mL, =0.004). NfL levels were correlated with scores of the mini-mental state examination (r=-0.242, =0.021), clinical dementia rating (CDR) (r=0.291, =0.005), or CDR-sum of boxes (r=0.276, =0.008). Just for participants who performed amyloid positron emission tomography (PET), the levels were different between subjects with PET (-) (n=17, 25.95±13.25 pg/mL) and PET (+) (n=16, 63.65±81.90 pg/mL, =0.010). Additionally, plasma NfL levels were different between vascular dementia and vascular MCI, and between Parkinson's disease- dementia and no dementia.

Conclusions: This pilot study shows that in subjects with DAT, plasma NfL levels increase. Plasma NfL level correlated with cognitive and functional status. Further longitudinal studies may help to apply the plasma NfL levels to AD, as a potential biomarker for the diagnosis and predicting progression.