Podbit · The Peter Attia Drive
Astrocytes synthesize cholesterol via the desmosterol pathway, and plasma desmosterol correlates strongly with CSF desmosterol and brain cholesterol production. Studies show low plasma desmosterol is associated with higher rates of cognitive impairment — making it a clinically measurable proxy for brain cholesterol health.
Where this was said
At 44:50 · chapter starts 41:45
Peter asks about the two cholesterol synthesis pathways that share a common trunk before bifurcating at their penultimate sterol. Tom explains that in peripheral tissues, the lathosterol pathway dominates; in the brain, it is the desmosterol pathway — used by astrocytes — that is predominant. When neurons are young and actively synthesizing cholesterol, they use the lathosterol pathway; after age 10, when neurons stop making cholesterol, lathosterol production in the brain essentially ceases. Desmosterol, by contrast, continues to be produced by astrocytes throughout life and reflects ongoing brain cholesterol synthesis [1] — Tom Dayspring "Desmosterol as brain cholesterol marker: Plasma desmosterol correlates highly with cerebrospinal fluid desmosterol and brain tissue cholest…" 1:18:20 . The remarkable clinical implication: plasma desmosterol correlates highly with cerebrospinal fluid desmosterol, meaning a routine blood test can serve as a window into the brain's cholesterol factory. A study using mass spectrometry found that people with low desmosterol have higher rates of cognitive impairment and Alzheimer's disease. Tom also notes that desmosterol is commercially measurable, unlike 24S-hydroxycholesterol, which remains confined to research settings — though both are valuable biomarkers of brain cholesterol health.
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