The Alzheimer’s disease (AD) continuum spans from healthy aging to subjective cognitive decline (SCD), mild cognitive impairment (MCI), and dementia. Serum Neurofilament Light Protein (NfL) is a potential non-invasive biomarker for neurodegeneration. This study evaluates serum NfL across the cognitive decline continuum in an Indian cohort. To assess serum NfL as a biomarker for early and progressive neurodegeneration, including its diagnostic utility in SCD, MCI, and AD. This case-control study included 129 participants: 28 cognitively normal older adults (HC), 32 with SCD, 33 with MCI, and 36 with AD. Serum NfL levels were measured using Simoa ® technology. The association of NfL with cognitive decline was analyzed using a Generalized Linear Model (GLM) adjusted for age and sex, and receiver operating characteristic (ROC) curves assessed diagnostic performance. Serum NfL median levels progressively increased across groups: HC (21.1 pg/mL), SCD (28.94 pg/mL), MCI (35.5 pg/mL), and AD (48.64 pg/mL). Compared to HC, NfL levels were significantly higher in SCD (adjusted coefficient: 0.59, p = 0.004), MCI (0.72, p = 0.001), and AD (1.13, p < 0.001). ROC analysis showed good discrimination: AUC was 0.795 for SCD vs. HC, 0.908 for MCI vs.HC, and 0.941 for AD vs. HC. The study demonstrates a clear association between rising serum NfL levels and advancing cognitive decline. Serum NfL demonstrated potential as a sensitive and non-invasive biomarker for early detection and staging of cognitive decline. The establishment of population-specific cut-offs within an Indian cohort contributes to global efforts toward standardizing blood-based biomarkers for AD.
Rao et al. (Thu,) studied this question.