APP and Alzheimer disease: While a small number of studies reporting increased AHN [42, 43] in AD mouse models attributed their findings to differences in genetic backgrounds and transgene expressions and the timing of aberrant AHN in relation to the neuropathology stage, the currently observed cell proliferation deficit at 11.5 months of age is consistent with previous findings of impaired cell proliferation in the SGZ of APP/PS1 mice from as early as 1–2 months [44], by 3 months [45], by 6 months [46] and between 8–9 months of age [47].