NTRK1 and Alzheimer disease: Peng et al. have shown a negative correlation between proNGF levels and Mini-Mental Status Examination (MMSE) score, demonstrating that the accumulation of proNGF correlated with loss of cognitive function [84], whereas biochemical and immunocytochemical studies of TrkA, TrkB, and TrkC levels demonstrated their reduction in the nucleus basalis of Meynert in AD patients [85].