In the current study, the neurobiological changes reported might be attributed by the effect of BChE knockdown in hippocampal CA1 region; however, this will require further investigation (33).The observed strengthening of contextual fear memory is consistent with reports on mouse models of manganese-induced neurotoxicity, mouse models of stress, AD patients and animal models of AD; low BChE expression and decreased BChE function are associated with higher cognitive ability and higher stress levels (2, 4–7, 34). Here, BCHE is linked to Alzheimer disease.