In AD, more tau proteins are released into the extracellular space, which was observed in the CSF of AD patients as increased concentrations of both T-tau, measured using antibodies against mid-domain tau epitopes that are not phosphorylated, and P-tau that is measured using antibody combinations that specifically recognize mid-domain P-tau epitopes (Olsson et al., 2016). This evidence concerns the gene MAPT and Alzheimer disease.