A Skull Bone Marrow‐to‐Brain Axis Links Osteoblastic Activity to Myeloid Cell Trafficking, Cerebral Blood Flow, and Cognition in Alzheimer's Progression

mouse models. These vascular changes facilitate migration of SBM-derived myeloid cells into the meninges and cortex, improving cerebral blood flow (CBF) and slowing cognitive decline. Notably, these effects are age-dependent, emerging at 6 months but diminishing by 12 months. Enhancing this axis via bone marrow transplantation improves CBF and cognitive function in aged mice, whereas disrupting it through osteoblastic deletion of ATP6AP2 impairs both. Together, these findings reveal a previously unrecognized SBM-to-brain axis that regulates immune, vascular, and cognitive functions, highlighting systemic contributions to AD pathogenesis.