Cheng et al. (2017) later developed a bipartite peptide comprised of polyarginine-8 (R8) conjugated to the sequence of amyloid-beta25–35 (RRRRRRRRGSNKGAIIGLM; net charge +9.0) which effectively reduced cerebral accumulation of amyloid-beta and ameliorated cognitive deficits in the APP/PS1 double transgenic mouse model of AD. This evidence concerns the gene PSEN1 and Alzheimer disease.