Evaluation of serum NFL, T-tau, p-tau181, p-tau217, Aβ40 and Aβ42 for the diagnosis of neurodegenerative diseases.

Objectives: To assess the variations and diagnostic performance of serum biomarkers of neurodegenerative diseases.

Methods: In this monocentric prospective study, neurofilament light (NFL), T-tau, p-tau181, p-tau217, Aβ40, and Aβ42 were measured in serum collected from orthopedic patients (control group, n=114) and patients in the neurology department (n=69) previously diagnosed with Alzheimer's disease (AD, n=52), parkinsonian syndromes (n=10), and other etiologies of neurodegeneration (non-AD, n=7).

Results: In the control group, serum NFL, T-tau, p-tau181, p-tau217, and Aβ40 significantly increased with age, independently of sex. NFL (p=0.0078), p-tau217 (p<0.001) were significantly increased with neurodegeneration when compared to controls, with only p-tau217 significant in the multivariate analysis (p<0.001). Multivariate regression analysis accounting for age highlighted a significant increase of p-tau217 (p<0.001) in the AD subgroup. NFL was significantly increased in the non-AD patients (p<0.001), and in the parkinsonian syndromes subgroup (p=0.016) when compared to negative controls. Serum p-tau181 and p-tau217 were significantly correlated with CSF p-tau181 (Spearman's coefficients of 0.43 and 0.48 respectively, n=40). Areas under the ROC curves for the identification of patients with neurodegenerative diseases were 0.62 (0.54-0.70) for NFL, 0.62 (0.54-0.71) for T-tau, 0.83 (0.76-0.89) for p-tau217, and 0.66 (0.58-0.74) for Aβ40.

Conclusions: Serum biomarkers can help identify patients with neurodegenerative disease and may be a valuable tool for care and orientation. Phosphorylated tau p-tau217 is a promising blood biomarker for AD and NFL for other etiologies.