MAPT and Alzheimer disease: AD diagnostic criteria have been revised to include biomarkers divided into two categories: markers of amyloid pathology (decreased Aβ42 levels in the cerebrospinal fluid, positive PET imaging with amyloid ligands) and markers of neuronal damage/tau pathology (increased tau and phospho-tau in the cerebrospinal fluid, decreased glucose metabolism on FDG-PET, medial temporal lobe atrophy on MRI).