The World, the Universe and Us The Radical Theory That Could Force Us To Rethink Alzheimer’s
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Mar 11, 2026 Alice Klein, New Scientist reporter who covers research and investigations, explores a radical idea that Alzheimer’s might begin outside the brain. She outlines surprising genomic evidence, links to gum, lung and gut health, the role of inflammation and barrier tissues, and why amyloid and tau may not tell the whole story.
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Plaques Could Be A Defensive Response
- Some researchers think amyloid and tau may be defensive responses, not primary causes of damage.
- Mini‑brain experiments show adding herpes virus can provoke plaque formation, suggesting response-to-infection.
Genomic Study Points To Barrier Tissues
- A large genomic reanalysis looked at thousands of genomes and gene activity across brain and 40 body regions.
- Alzheimer risk variants showed far higher activity in barrier tissues like skin, lungs and gut than in brain cells.
Risk Genes Cluster In Immune Barrier Tissues
- Many Alzheimer's risk genes are linked to immune regulation and are active in barrier tissues that face germs and toxins.
- That pattern suggests inherited inflammatory responses in these tissues might set off processes that later affect the brain.