PSEN1 and Alzheimer disease: Although the human tau gene MAPT mutations per se only cause frontotemporal dementia (FTD) rather than AD,462 tau mediates Aβ toxicity to promote the pathological process of AD.92,137 The interaction between Aβ and tau is under investigation by the generation of transgenic mouse models expressing human tau and APP, including APP/PS1/rTg21221,463 3xTg-AD (APP Swedish, MAPT P301L and PSEN1 M146V)464 and PLB1-triple465 mice.