Early diagnosis of Neurodegenerative diseases (NDDs) and accurate patient profiling are key goals needed to tailor prompt personalized therapeutic strategies that can significantly impact disease progression and patients' quality of life. The project will validate a novel, cost-effective and quick biophotonic-based method for early and differential diagnosis of NDDs (Parkinson's disease, atypical parkinsonisms, Alzheimer's disease) and for routine clinical monitoring of NDD progression (longitudinal study). Raman spectroscopy (RS) will be applied to biochemically profile saliva and salivaderived Extracellular Vesicles (sEVs) and to identify a spectroscopic biomarker for NDDs. Optimized protocols for RS will be used to concomitantly evaluate saliva and sEVs from people with NDDs and to detect salivary changes in the biochemical profile, with special focus on EV-associated components. The accuracy of the method in discriminating NDDs at different disease stages and during disease progression will be verified. A nanotechnology-based biomolecular characterization of saliva and sEV will clarify the involvement of specific pathological molecules in NDDs progression.