Potential Bio‐signal Links between Alzheimer’s Disease and Osteoporosis

Low bone mineral density is associated with the development of Alzheimer’s disease (AD). The patients with AD have an early‐onset bone loss with a rapid progression before cognitive symptoms appear. Yet the pathophysiological relationship is not well understood between two clinical conditions. Microglia and osteoclasts share developmental origins and are commonly classified as tissue‐specific macrophages in brain and bone, and are responsible for pathological changes in AD and osteoporosis, respectively. Interestingly, Polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (PLOSL), caused by mutations in TREM2 or DAP12 genes, present bone pathology followed by presenile dementia.