Overall, the findings from these studies indicate that changes in NPY occur in transgenic animals, both at early stages (subregional decreased number of immunoreactive NPY and PV cells in 1-month-old TgCRND8 mice with AD, increased vulnerability of NPY-expressing GABAergic neurons in the same model, decreased NPY mRNA expression in PS1 × APP mice at 4–6 months), and as the disease ages and progresses (aberrant NPY expression, reflecting profound remodeling of inhibitory and excitatory circuits in the dentate gyrus in Tg2576 mice). This evidence concerns the gene NPY and Alzheimer disease.