As the disease progresses, AD patients exhibit further abnormalities, such as down regulation of neurotrophic factors including brain-derived neurotrophic factor (BDNF) through dysregulation of the glutamatergic N-methyl-D-aspartate receptor (NMDAR) which can cause Aβ-induced neuronal loss and dendritic atrophy (Meng et al., 2013). This evidence concerns the gene BDNF and Alzheimer disease.