This paper explores the promise of induced pluripotent stem cells as a model system for the study of neurodegenerative diseases of Alzheimer’s, Parkinson’s and other diseases of the aging brain. Research in these areas, as in neuroscience more broadly, has struggled with the imperfect mapping between human and animal brains. The paper argues that the contemporary promise of induced pluripotent stem cells for research is established through their potential to resolve problems of translation, bridging laboratory and clinical contexts by acting as a model of “real” patient bodies. However, the paper shows how this promise is contested and renewed through a rearticulation of the relationship between neurodegeneration, aging and the qualities of “young” and “aged” bodies. This not only results in the introduction of new qualities and attributes to the model system, but also a re-imagining of how aging features within both late and early-onset neurological diseases.