BDNF and Alzheimer disease: In fact, significant literature supports deficits in BDNF expression in AD (Fahnestock et al., 2002; Peng et al., 2005; Fahnestock, 2011) and also disruptions of NGF and its receptor, TrkA, with concomitant effects on attention, learning, and memory (Mufson et al., 1996, 2005, 2007; Counts et al., 2004; Peng et al., 2004; Perez et al., 2011; Parikh et al., 2013).