MAPT and Alzheimer disease: Selection of appropriate biomarkers to detect early AD or monitor progress is complex since numerous biomarkers are applicable, such as positron emission tomography (PET) amyloid imaging, fluorodeoxyglucose PET to detect hypometabolism, CSF tau, MRI to detect brain atrophy, and CSF YKL-40 (an indicator of activated microglia) (Zetterberg and Bendlin, 2020).