'Alzheimer's may start in the nose', says BBC Traitors star Professor Hannah Fry

'Alzheimer's may start in the nose', says BBC Traitors star Professor Hannah Fry Research has found an interesting link between our brains and our nose There is a theory that Alzheimer's could "start in the nose" long before signs of memory loss become obvious, a TV professor has shared. Celebrity Traitors star and mathematician Professor Hannah Fry spoke about the research in her column for New Scientist. The broadcaster, who lost her father to Alzheimer's in 2025, explained that the theory suggests that "maybe [Alzheimer's] starts way, way, way, way, way before we thought". Experts are suggesting that "this isn't just something that goes wrong in your brain". Hannah claims that this new theory comes from several forms of research that the condition may have more to do with our noses than experts have ever believed. In an Instagram video, she explained how our brains are "locked away" inside our skulls, with very little able to get inside. She said: "One of the few areas where [the brain] has a connection to the outside is through your nose. Just behind your eyes, sitting behind your nose, there is like a little bit of your skull that is covered in tiny holes through which your olfactory nerves will dangle to give you your sense of smell." This collection of research found that this could be a potential route for infection into the brain. Professor Fry shared that the studies involved mice, dogs and people living in heavily polluted areas. She said: "A group of scientists took a bunch of mice, and then they squirted chlamydia up their noses. Now it was chlamydia pneumonia, which is a sort of bacterial cousin of the one that gives you an STI, but why let facts get in the way of a good sentence? "To their surprise, within 72 hours, these mice who just had something put into their nose had an infection that travelled up into their brains that had then triggered the same kind of inflammatory response and plaques that you see in brains that are riddled with Alzheimer's." Similar research found that stray dogs in Mexico living in cities with severe pollution had "tiny little flecks of metals embedded inside of their brain". Hannah said: "[The study found] each one of those fragments was then surrounded again by the same plaques, same inflammatory responses that you end up seeing in Alzheimer's." The latest research has examined young children and adults who grew up in heavily polluted areas and found the same pattern. It theorised that something "sniffed up from the environment" was fought off by the brain. The areas were then surrounded by these plaques and by an inflammatory response commonly seen in people with Alzheimer's. Alzheimer's disease is a progressive condition and the most common cause of dementia in the UK, according to the NHS. For help and support on navigating the condition, click here for more information from the Alzheimer's Society.