Alzheimer's disease may begin in the nose, according to hopeful research highlighted by the charity Alzheimer's Research UK, which notes that the olfactory system can reveal more about health than many realise.
Mathematician and Celebrity Traitors star Hannah Fry has also suggested that the nose could offer crucial clues to understanding the disease. In an Instagram video, she said: "One of the few areas where [the brain] has a connection to the outside is through your nose."
Mouse Study and Pollution Findings
Professor Fry explained that a group of scientists took mice and squirted chlamydia pneumonia up their noses. She described it as "a sort of bacterial cousin of the one that gives you an STI."
"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," she said.
She also pointed to a study comparing stray dogs in Mexico's polluted cities with those in rural areas. Researchers found tiny metal particles in the city dogs, thought to come from vehicle emissions. Those fragments were "surrounded again by the same plaques, same inflammatory responses that you end up seeing in Alzheimer's."
Charity's Position on the Link
Emma Taylor, Senior Information Officer at Alzheimer's Research UK, said the nose may hold clues that could help better understand the disease, but more research is needed.
She said: "Possibly. Researchers are becoming increasingly interested in the link between the nose and the brain. We know that changes in a person's sense of smell can happen years before symptoms of some diseases that cause dementia appear. Scientists are also investigating whether factors such as air pollution, inflammation and infections could affect brain health through the nose."
On whether dementia starts in the nose, Taylor added: "It's an intriguing idea, but we don't know enough yet to say that's the case. Changes in a person's sense of smell can happen years before symptoms of some diseases that cause dementia appear. Researchers are exploring whether this means the nose is simply an early warning sign, or whether it could be involved in some of the earliest stages of disease."
She stressed: "For now, the evidence isn't strong enough to say that dementia begins in the nose."
Potential for Diagnosis and Treatment
While there is no cure, Taylor said there is hope that the nose could hold the key to more answers. She concluded: "Because of the close connection between the nose and the brain, researchers are exploring whether smell tests, nasal samples or medicines delivered through the nose could help diagnose or treat diseases that cause dementia. While these approaches show promise, more research is needed before they become part of routine care."
Alzheimer's disease is a condition that progressively damages the brain, eventually leading to dementia and problems with memory and thinking. It is the most common cause of dementia.
The most common early symptoms include language problems, changes in mood, changes to how people see and hear things, thinking and reasoning difficulties, and memory problems. Alzheimers.gov warns that a loss of smell, known as anosmia, is a key early sign of Alzheimer's-related cognitive impairment and may appear before diagnosis.
