Moreover, significant downregulation of TrkA, TrkB, and TrkC was seen in single CBF neurons microaspirated from the nbM of MCI and AD compared to NCI (Ginsberg et al., 2006b) (Figure 9A), consistent with observations in another vulnerable cell type, hippocampal CA1 pyramidal neurons (Ginsberg et al., 2000, 2010). This evidence concerns the gene NTRK1 and Alzheimer disease.