HTT and Alzheimer disease: In a first test, we constructed human cell‐based models for AD, HD, SCA1, and SCA3 by expressing ND‐causing genes (Aβ1–42, Htt‐Q74, Atx1‐Q52, and Atx3‐Q84) in HEK293 cells and evaluated the impact of Akt1 activation on cell phenotypes.