Alzheimer’s “Starts in the Nose”: The Evidence So Far — SkimNews
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- Aviv Regev said at an August conference that “we now know that Alzheimer’s starts in the nose,” a claim that prompted Fry’s inquiry into the hypothesis.
- People with Alzheimer’s often lose their sense of smell years before memory-loss symptoms; a 2014 study found that smell loss predicted death within five years in older people better than a cancer diagnosis.
- A six-month study placed essential-oil diffusers beside older people’s beds, and participants receiving olfactory enrichment performed better on memory tests than the control group, though the sample was small.
- A 2022 mouse experiment introduced Chlamydia pneumoniae through the mice’s noses; within 72 hours, the bacteria traveled through nasal nerves into the brain and triggered beta-amyloid accumulation.
- Stray dogs in Mexico that breathed polluted air had microscopic metal particles in their brains alongside inflammation and beta-amyloid; dogs living in cleaner, rural environments did not show the same pattern.
- Studies of children and young adults who died from gun violence or car accidents found metal-rich particles thought to come from exhaust and brake dust, alongside inflammation and beta-amyloid, in brains sometimes only a few years old.
- The cribriform at the top of the nose is riddled with holes where olfactory fibres pass through, creating a potential route past the brain’s defenses; Fry concludes that no one nose has the answer.
Why it matters: For Alzheimer’s researchers and clinicians, the 72-hour mouse result and pollution findings in children’s brains expand research beyond plaques to candidate nasal triggers. Because the source establishes no causation in people, the evidence changes what can be investigated without settling prevention or treatment priorities.
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