BCHE and Alzheimer disease: After cymserine, several cymserine derivatives have been synthesized with greater selectivity for BChE than cymserine, and several of them were tested in animals demonstrating the ability to increase brain ACh levels and produce nootropic effects, as well as reducing levels of amyloid precursor protein and Aβ [30], but so far only bisnorcymserine has entered phase I clinical trials for the treatment of AD [33].