MAPT and Alzheimer disease: In AD, identification of amyloid β (Aβ) and phosphorylated tau (p-tau) as major components of extracellular plaques and neurofibrillary tangles led to establishment of the core biomarkers for the disease, with a CSF profile characterised by decreased Aβ42 levels, and elevated levels of total tau (t-tau) and p-tau (for example at threonine 181) [4].