CHI3L1 and Alzheimer disease: Unfortunately, no study in humans has yet linked levels of the well-established and emerging serum/CSF biomarkers of AD (i.e., tau protein, phosphorylated tau-181, neurogranin, chitinase-3-like protein 1, neurofilament light, synaptosomal-associated protein-25, amyloid-beta-40 and amyloid-beta-42 isoforms, visinin-like protein 1, and blood alpha-2 macroglobulin [193, 206–210–211]) with alterations of the meningeal lymphatic system.