MAPT and Brain atrophy: Currently, two main groups of biomarkers can assist in the diagnosis of MCI: amyloid beta (Aβ) deposits (such as cerebrospinal fluid concentrations of Aβ42 and positron emission tomography (PET) amyloid imaging) and neuronal damage (such as CSF tau/phosphorylated tau, hippocampal volume or medial temporal atrophy, rate of brain atrophy, fluorodeoxyglucose (FDG) PET imaging and SPECT perfusion imaging) [6].