NTRK1 and Alzheimer disease: TrkA protein levels are reduced in the cortex (BFCN terminal axons) of AD patients (Mufson et al., 1997; Counts et al., 2004; Ginsberg et al., 2006), while many studies, but not all, report no change in p75NTR levels (Counts et al., 2004; Mufson et al., 2005, 2007; Ginsberg et al., 2006).