APP/PS1 mice administered adeno-associated virus (AAV, serotype 2) harboring CBD3 demonstrated: (i) reduced levels of Aβ1–42 and phosphorylated-tau (a marker of AD progression), (ii) reduced apoptosis in the hippocampus, and (iii) reduced cognitive decline compared with APP/PS1 mice or APP/PS1 administered a control virus. The gene discussed is MAPT; the disease is Alzheimer disease.