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Why some people with the strongest Alzheimer's gene stay sharp
The full story behind my Short: Columbia researchers show how excess fibronectin, driven by APOE4, makes the blood-brain barrier leaky, explaining why a rare FN1 variant protects some carriers (Nature Aging, 2026).
The short version
About 1 in 5 people carry APOE4, the strongest common genetic risk factor for Alzheimer's. In 2024 Columbia researchers found a rare FN1 (fibronectin) variant linked to 71% lower odds of Alzheimer's in people with two APOE4 copies. Their new Nature Aging study shows why: APOE4 drives fibronectin to pile up around brain blood vessels. APOE4 mice had nearly twice as much fibronectin and a leaky blood-brain barrier; adding fibronectin to astrocytes was enough to cause leaks, and reducing it improved barrier function. Excess fibronectin jams growth signals that keep the barrier sealed. Drugs mimicking the protection are possible, but this is lab and animal work with no treatment yet (Bhattarai et al., Nature Aging 2026, Columbia University).
1 in 5people carry at least one APOE4 copy [2]
−71%odds of Alzheimer's with the FN1 variant, two APOE4 copies (OR 0.29) [3]
~2xfibronectin in APOE4 vs APOE3 mice [1][2]
0treatments yet: lab and animal work [2]
What happened
The team combined human brain tissue and cerebrospinal fluid, genetic and epigenetic analyses, single-cell sequencing, spatial imaging, human stem-cell and 3D blood-vessel models, zebrafish and mice. APOE4 promoted fibronectin build-up around brain blood vessels. Raising human fibronectin in astrocytes was enough to make the barrier leaky; reducing it improved barrier function. Excess fibronectin triggers abnormal integrin and focal adhesion kinase signalling that disrupts VEGF, HB-EGF and IGF-1 growth-factor signals [1][2].
Watch the Short
About this page
The Short uses illustrative photos and images from Wikimedia Commons (credited below) and my own sketches; the person in the opening photo is not connected to the study.
The narration is an AI clone of my own voice, used with my consent.
Why it matters
- A natural shield to copy. The rare FN1 variant points to a target: stop fibronectin piling up, block its signals, or restore the growth factors [2].
- Early, not late. It links a major risk gene to early blood-vessel damage that might be measurable and modifiable [2].
- Careful drug design. Fibronectin is essential for tissue structure and healing, so any drug must target only the harmful build-up [2].
Full narration (transcript)
Can someone explain why some people carry the strongest common Alzheimer's gene, yet stay sharp into their 80s? So let's talk about what's actually happening here. That gene is APOE4, carried by about one in five people. Columbia scientists found a rare protective mutation in a gene called FN1. In people with two APOE4 copies, it cut the odds of Alzheimer's by 71 percent, to under a third. FN1 makes fibronectin, a sticky tissue protein. With APOE4, too much piles up around brain blood vessels. In mice with human APOE4, fibronectin nearly doubled, and the blood-brain barrier leaked. And here's where it gets interesting: adding fibronectin to the barrier's support cells alone caused leaks. It jams the growth signals that keep the barrier sealed. Cut fibronectin back in those cells, and the barrier worked better again. Why it matters: a drug mimicking that mutation could one day protect brains. Caveat: lab and animal work, no treatment yet. For the full story, follow the link in the description.
Sources
- [1] Bhattarai P., Yilmaz E. et al. (2026). “Fibronectin mediates APOE4-driven blood–brain barrier dysfunction in Alzheimer’s disease.” Nature Aging 6(9): 1901. doi.org/10.1038/s43587-026-01204-0
- [2] Columbia University Irving Medical Center (2026). “The Brain’s Blood Vessels May Hold a Key to Alzheimer’s—and Protection From It.” cuimc.columbia.edu
- [3] Bhattarai P. et al. (2024). “Rare genetic variation in fibronectin 1 (FN1) protects against APOEε4 in Alzheimer’s disease.” Acta Neuropathologica. doi.org/10.1007/s00401-024-02721-1
- [4] ScienceDaily (19 Oct 2026). “Why some people escape Alzheimer’s despite carrying a high-risk gene.” sciencedaily.com
Credits
Photos and images via Wikimedia Commons (illustrative): Karen Elder (Unsplash).jpg (Capturing the human heart (zjtcpts) via Unsplash, CC0); Alzheimer's disease brain comparison.jpg (Garrondo, from NIA / ADEAR images, Public domain); DNA Double Helix by NHGRI.jpg (National Human Genome Research Institute, Public domain); Columbia University Medical Center Herbert Irving Pavilion and Millstein Hospital Building.jpg (Beyond My Ken, CC BY-SA 4.0); Alzheimer's disease brain severe.jpg (NIA / ADEAR (US National Institute on Aging), Public domain); Protein FN1 PDB 1e88.png (Emw, CC BY-SA 3.0); Lab mouse mg 3176.jpg (Rama, CC BY-SA 2.0 fr); Astrocyte (NIH BioArt 671 - 764145).png (NIAID (NIH), Alexander Stewart, Public domain); Danio rerio lab left.JPG (Pogrebnoj-Alexandroff, CC BY-SA 3.0); Blood vessels-mouse brain section.png (Antonino Paolo Di Giovanna, Ludovico Silvestri, Marie Caroline Muellenbroich, CC BY-SA 4.0). Sketches and animation: my own. Narration: synthetic voice.