The injection of AAV vectors carrying mutated forms of human APP and PS1 into the mouse hippocampus led to the stable production [24, 25] of APP, βCTF and Aβ peptides, at levels similar to those observed in the hippocampus from AD patients and significantly lower than those present in the hippocampus of APP/PS1ΔE9 transgenic mice. Here, PSEN1 is linked to Alzheimer disease.