The development of human induced pluripotent stem cells (iPSC) and their subsequent differentiation into neurons has provided new opportunities for the generation of physiologically-relevant, in vitro disease models. I will present our work using iPSC to modal familial Alzheimer's Disease (fAD) and Frontotemporal Dementia (FTD). We have investigated the mutation-specific effects of APP and PSEN1 mutations on Abeta generation in neurons generated from individuals with fAD, revealing distinct mechanisms that may contribute to clinical heterogeneity in disease. I will also discuss our work to understand the developmental and pathological changes to tau that occur in iPSC-neurons, particularly the challenges of understanding tau pathology in a developmental system, tau proteostasis and how iPSC-neurons may help us identify early signatures of tau pathology in disease.