Alzheimer's, stroke, multiple sclerosis, and other neurological diseases cause severe damage due to neuroinflammation mediated by immune cells. Managing this inflammation poses a significant medical challenge because the brain is protected by the skull and additional surrounding membranes that make the brain less accessible for treatment approaches. Scientists had previously discovered pathways going from the bone marrow of the skull towards the brain, allowing immune cell movement. Now, new research revealed that cells in the skull’s bone marrow are unique in their composition and in their disease response. These findings offer new possibilities for the diagnosis and treatment of neurological diseases and revolutionize brain health monitoring in the future with non-invasive skull imaging. The results are now published in Cell.