# Bone marrow cells in brain linked to Alzheimer > Live situation record from CLSTR: https://clstr.news/situations/bone-marrow-cells-in-brain-linked-to-alzheimer > Updated: 2026-08-06T04:21:00.000Z. Sources: 6. Developments: 2. Researchers at Stanford University reported that immune cells originating in the bone marrow can enter the human brain and resemble microglia. An initial pre‑print described the discovery in brain tissue from older adults and noted that clonal hematopoiesis—a condition where blood cells derive from a single stem cell—was associated with a reduced risk of Alzheimer disease. A follow‑up report, published in Nature, expanded the findings, showing that aging is accompanied by a substantial influx of these bone‑marrow‑derived immune cells. Analysis of large genetic cohorts confirmed that individuals with specific clonal hematopoiesis mutations were less likely to develop Alzheimer’s, suggesting a possible protective role. The later article also placed the results in a broader context, linking systemic health conditions to brain structure and function through advanced neuroimaging. Together, the studies challenge the view of the brain as an isolated organ, highlight a peripheral‑central immune connection, and propose that bone‑marrow‑derived cells may influence neurodegeneration. ## Timeline ### 2026-08-06: Stanford study shows aging drives immune cells into the brain Stanford researchers found that aging brings immune cells into the brain, overturning the view of a closed brain system and linking clonal blood mutations to lower Alzheimer’s risk; systemic diseases also alter 3 sources. https://clstr.news/cluster/stanford-study-shows-aging-drives-immune-cells-into-the-brain ### 2026-07-31: Stanford Study Finds Bone Marrow Cells in Brain Influence Alzheimer Stanford researchers discovered bone‑marrow‑derived immune cells in the brains of older adults, forming a large share of microglia and linked to reduced Alzheimer risk, challenging previous mouse‑based views. 3 sources. https://clstr.news/cluster/stanford-study-finds-bone-marrow-cells-in-brain-influence-alzheimer --- Cite as: Bone marrow cells in brain linked to Alzheimer. CLSTR, https://clstr.news/situations/bone-marrow-cells-in-brain-linked-to-alzheimer