MAPT and Alzheimer disease: Thus, apart from Alzheimer’s disease (AD), in which changes in the CSF levels of certain tau and amyloid-beta isoforms reflect the ongoing deposition of these proteins in the brain, surrogate markers of neuronal damage such as 14-3-3, total tau and neurofilament proteins represented the only available biofluid markers to support the clinical diagnosis of neurodegenerative diseases until recently [85].