NEFL and Alzheimer disease: On the contrary, no changes in amyloid-β peptide, tau protein, Neurofilament Light chain (NfL) and other AD markers have been detected in peripheral olfactory neurons from individuals with persistent (for 6 to 10 months) post-COVID-19 hyposmia when compared to age/sex-matched healthy controls, indicating that the loss of smell due to SARS-CoV-2 infection is not likely to predispose to future neurodegeneration [124].