Skull bone marrow grows measurably fattier with age in people
The inside of your skull contains bone marrow that becomes progressively fattier as you age. Until now, measuring this change in large human populations was not feasible. A new AI tool makes it possible using routine brain scan data.
Researchers developed an artificial neural network that localises bone marrow in the skull (calvarium) on T1-weighted MRI head scans. The study, published in eLife, applied this tool to large datasets collected primarily for brain research but containing usable skull information as well.
What the scans revealed
Bone marrow fat in the skull increases with age. Post-menopausal women showed an accelerated rise. Men had higher average fat content than women across the lifespan. The researchers identified 41 genetic locations significantly associated with the trait, including six that were sex-specific.
A notable feature of calvarial bone marrow is that it has direct vascular channels connecting it to the meninges. Blood cells travel in both directions between skull and brain through these channels. This makes it biologically plausible that calvarial marrow state could influence the brain. The researchers also found statistical associations between skull marrow fat and cognitive ability and Parkinson’s disease, though they emphasise these are correlations, not causal links.
Why this matters for aging research
Calvarial bone marrow converts from red to yellow later in life than marrow in the limbs, potentially making it a useful normative marker of aging. The AI tool makes it feasible to measure this at population scale in existing MRI biobanks without additional scanning.
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- bone marrow adiposity MRI aging
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