Plasma neurofilament light chain levels in Alzheimer's disease.

Plasma neurofilament light (NFL) levels may be a marker of neuronal injury. We examined whether plasma NFL might be a potential biomarker for the prodromal and dementia stages of AD. Participants included 193 cognitively normal (CN), 198 amnestic mild cognitive impairment (aMCI) and 187 Alzheimer's disease (AD) individuals enrolled in the Alzheimer's Disease Neuroimaging Initiative (ADNI). Plasma NFL levels were examined by the Single Molecule array (Simoa) technique. Our results showed significantly increased plasma NFL levels in both AD (50.9pg/ml) and aMCI (43.0pg/ml) groups compared to CN (34.7pg/ml) group (both p<0.001), but with substantial overlap between the groups. Plasma NFL levels in AD group was also markedly increased, compared with aMCI group (p<0.001). Plasma NFL levels were positively associated with age (r=0.355, p<0.001) and negatively with global cognition (r=-0.355, p<0.001) in all subjects. Our results suggest that plasma NFL levels may not be a useful biomarker for the diagnosis of prodromal and dementia stages of AD.