Brain-permeable small molecule inhibitors of beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), namely verubecestat, lanabecestat, and LY3202626, have demonstrated considerable efficacy in reducing the production of amyloid-beta (Ab) in individuals with healthy cognitive function as well as those with prodromal, mild, or moderate AD. This evidence concerns the gene BACE1 and Alzheimer disease.