NTRK1 and Alzheimer disease: These results clearly demonstrated that the combined modulatory actions of NGF on the presynaptic morphology and neurosecretory function(s) of in vitro cholinergic septal primary neurons were directly and causally linked via the stimulation of NGF/TrkA signaling (Figures 8A–C), pointing out the pathological relevance of the lack in NGF availability in the earliest synaptic deficits occurring at the onset of AD progression.