Two Landmark Studies Challenge Dogma About our Brain Immune Cells and Aging

Two Landmark Studies Challenge Dogma About our Brain Immune Cells and Aging

August 30, 2026 · 44 min

About this episode

The episode discusses two landmark studies that challenge existing beliefs about brain immune cells and their role in aging.

This podcast is meant to complement my recent Ground Truths post Why Our Memory Slips After Age 50 which has all the relevant links to the 2 papers, key graphics, and other related publications. If you haven’t had a chance to read that, it would be helpful to spend a few minutes to do so before listening to this podcast. Links to the 2 papers for those who don’t want to look back Zemke et al in Science https://www.science.org/doi/10.1126/science.adt8307 Belk et al in Nature https://www.nature.com/articles/s41586-026-10939-0 It’s a major and fascinating discovery. We’re talking about a “hostile takeover” of blood monocyte cells that invade the brain and ultimately completely replace the brain microglia. The problem is these new microglia are pro-inflammatory. A surprising finding is about CHIP (blood stem cells with mutations known as clonal hematopoiesis of indeterminate potential) that was shown to be protective. It’s surprising because CHIP is common with age and until now it has been linked to bad things such as cardiovascular disease, clotting, and cancer. If this pans out, it introduces the concept of immunotherapy of the blood (“brain immunotherapy”). We discussed recent…

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