Why some people escape Alzheimer’s despite carrying a high-risk gene — SkimNews
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- Columbia University researchers published a study in Nature Aging identifying how excess fibronectin damages the blood-brain barrier in carriers of APOE ε4, the strongest common genetic risk factor for Alzheimer's disease.
- APOE ε4 carriers showed nearly twice as much fibronectin accumulation in the brain compared to mice carrying APOE ε3, with the buildup directly linked to a leakier blood-brain barrier.
- A rare FN1 gene mutation found in some APOE ε4 carriers who remain cognitively sharp into their 80s limits fibronectin accumulation around brain blood vessels, preserving barrier integrity.
- Excess fibronectin activates abnormal integrin and focal adhesion kinase signaling, disrupting the VEGF, HBEGF, and IGF1 growth factor networks that astrocytes and blood vessel cells use to maintain a healthy barrier.
- Human brain tissue and cerebrospinal fluid samples showed elevated fibronectin associated with astrocyte inflammation, with genetic analyses connecting FN1 to blood vessel disease and VEGFA changes.
- APOE ε4 is carried by approximately one in five people and increases Alzheimer's likelihood without guaranteeing the disease, making the protective mutation a potential template for treatment.
- Three potential treatment strategies emerged from the findings: preventing fibronectin buildup, blocking the abnormal integrin signaling, or restoring the disrupted growth factor communication between astrocytes and blood vessel cells.
Why it matters: Roughly one in five people carry APOE ε4, the strongest common Alzheimer's risk gene, yet some remain cognitively sharp into their 80s — and this study reveals the vascular mechanism (fibronectin-driven blood-brain barrier breakdown) that a rare FN1 mutation naturally blocks. That gives drug developers concrete molecular targets and biomarkers for measuring whether experimental therapies are protecting the barrier before symptoms appear.
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