NTRK2 and Alzheimer disease: In the brain of AD patients there is a molecular dysregulation of the main players of BDNF signaling namely, decreased levels of BDNF and TrkB-FL and increased levels of TrkB-Tc (Phillips et al., 1991; Connor et al., 1997; Ferrer et al., 1999; Kemppainen et al., 2012).