MAPT and Alzheimer disease: But there are more interactions of AD and BDNF: a specific loss of BDNF was found in tangle-bearing neurons (Ferrer et al.1999; Murer et al.1999), and BDNF dephosphorylates Tau including the most crucial sites for microtubule binding through TrkB activation and a PI3-kinase/Akt-dependent mechanism in a cellular model (Elliott et al.2005), implicating a direct Tau–BDNF interaction.