SORL1 and Alzheimer disease: Proliferative, pluripotent NPCs persist in the ageing brain33 and there is a greater decrease in adult hippocampal neurogenesis in Alzheimer’s disease cases than in healthy controls.32 Our findings in SORL1−/− NPCs are in keeping with this: there were fewer nuclei positive for the multipotent neural stem cell marker Sox2 than in wild-type cultures.