MAPT and Alzheimer disease: Recent studies have shown that cerebrospinal fluid (CSF) biomarkers of neurodegenerative processes in AD (e.g., concentrations of amyloid beta1– 42 (Aβ42), total tau, phospho-tau-181 (p-tau181), and the tau/Aβ42 ratio) may reflect underlying AD pathophysiology long before changes in memory and cognition are clinically detectable [7, 8].