In this study, there was no relationship between cortical choline acetyltransferase (ChAT) activity, the rate-limiting enzyme for acetylcholine synthesis, and levels of NGF, nor between reduced numbers of ChAT- (Gilmor et al., 1999), TrkA- (Mufson et al., 2000), or p75NTR− (Mufson et al., 2002b) containing neurons in MCI and mild AD. This evidence concerns the gene NTRK1 and Alzheimer disease.