MAPT and Alzheimer disease: These AD biomarkers include those that indicate Aβ deposition, such as decreased CSF Aβ or increased tracer retention on specific amyloid PET, and valid indicators of neuronal injury, such as increased CSF total tau/p-tau, hippocampal and/or medial temporal lobe atrophy on MRI, and temporal/parietal hypometabolism detected by fluorodeoxyglucose (FDG) PET.