Tear-based vibrational spectroscopy for non-invasive biomarker discovery in Amyotrophic Lateral Sclerosis

In recent literature, tear's biomarkers analysis through spectroscopic techniques is emerging as a reliable tool to identify neurodegenerative diseases such as Alzheimer's and Parkinson's syndromes. The focus of this work is to discuss the results of the application of Raman Spectroscopy on tears collected from patients affected by Amyotrophic Lateral Sclerosis (ALS), comparing to healthy controls. Showing high specificity and sensitivity, both differential and multivariate analysis have reported differences in spectral components, principally identified in two peaks related to Phenylalanine and Amide I. Furthermore, as distinctive for the neurodegenerative diseases, protein and lipids alterations have been found. The results, being confirmed by a parallel study conducted by infrared (IR) spectroscopy on the same samples, lead to the prospect of defining the technique supportive in the diagnosis of ALS, exploiting tears as a source of biomarkers.