BDNF and Alzheimer disease: Despite these limitations, the findings presented here are in line with those of a previous study that showed that intrahippocampal transplantation of murine NSCs resulted in an increased secretion of brain-derived neurotrophic factor (BDNF) and synaptic density, as well as improved cognition in aged 3xTg-AD mice harboring a heavy Aβ plaque burden and neurofibrillary tangle pathology [22].