MAPT and Alzheimer disease: The biomarkers in use aim at the in vivo assessment of markers of pathophysiology [amyloid positron emission tomography (PET), low cerebrospinal fluid (CSF) Aβ42, and elevated phosphorylated tau (P-tau) and neurodegeneration (AD pattern of FDG PET hypometabolism and hippocampal atrophy on MRI)].