Giorgia Tosoni, Dilara Ayyildiz, Sarah Snoeck, Elena P. Moreno‐Jiménez, Amber Penning, Estibaliz Santiago-Mujika, Olmo Ruiz Ormaechea, Hyunah Lee, Suresh Poovathingal, Kristofer Davie, Julien Bryois, Will Macnair, Jasper J. Anink, Luuk E. De Vries, Sahand Farmand, Erik Nutma, Dick F. Swaab, Eleonora Aronica, Jinte Middeldorp, Sandrine Thuret, Laurent Roybon, Onur Başak, Carlos P. Fitzsimons, Paul J. Lucassen, Evgenia Salta
The existence and functional significance of immature neurons in the adult human brain, particularly in the context of neurodegenerative disorders, remain an open question. Although rodent studies have highlighted active roles for adult-born immature neurons in the hippocampus both under healthy conditions and in Alzheimer's disease (AD), evidence from the human brain is limited and lacks detailed molecular characterization. To address this gap, we performed single-nucleus RNA sequencing in aged healthy, AD, and dementia-resilient human hippocampus samples to probe immature neuronal signatures and gene expression alterations associated with AD pathology and resilience. By applying an integrated experimental and computational pipeline, we identified persistent populations of immature neurons across all donor groups, with transcriptional profiles reflecting "juvenile" cellular functions, which are compromised in AD. Our findings suggest that the presence of these immature neuronal populations per se may actively contribute to maintaining homeostasis within the aged human hippocampus and to cognitive resilience in AD.