MAPT and Alzheimer disease: Today, biomarkers for the detection of preclinical AD progression include: ratio Aβ42:Aβ40, total tau (T-tau), and phosphorylated tau (P-tau) in cerebrospinal fluid (CSF) [40,41], measured using positron emission tomography (PET) with tracers specific for Aβ, tau, and synaptic impairment [42].