Scientists have identified a possible link between nose picking and an increased risk of developing Alzheimer’s disease, although the evidence remains preliminary and largely based on animal studies.
According to research published in 2022 by a team at Griffith University in Australia, damage to the inside of the nose may allow certain bacteria to reach the brain more easily. This process could trigger biological responses similar to those seen in Alzheimer’s disease.
The study focused on a bacterium called Chlamydia pneumoniae, which is known to infect humans and cause pneumonia. The bacterium has also been found in most human brains affected by late-onset dementia.
In experiments conducted on mice, researchers discovered that the bacteria could travel from the nasal cavity to the brain via the olfactory nerve, which directly connects the nose to the brain.
The findings showed that when the nasal epithelium, the thin tissue lining the roof of the nasal cavity, was damaged, infections in the nervous system became more severe. This led to increased deposits of amyloid-beta protein in the brain.
Amyloid-beta is released as part of the body’s response to infection, and clumps of this protein are commonly found in high concentrations in people with Alzheimer’s disease.
Researchers were also surprised by how quickly the infection spread in mice, reaching the central nervous system within 24 to 72 hours. Scientists believe the nose may serve as a rapid pathway for bacteria and viruses to access the brain.
Despite these findings, researchers emphasize that the results have not yet been confirmed in humans. It is also unclear whether amyloid-beta plaques directly cause Alzheimer’s disease or are part of a protective immune response.
Nose picking is a common behavior, with estimates suggesting that up to 90 percent of people engage in it. However, the researchers caution that damaging the lining of the nose, whether through picking or plucking nose hairs, may increase the risk of bacteria entering the brain.
A 2023 review led by researchers from Western Sydney University further explored this hypothesis. The review suggested that the olfactory system could be a plausible pathway for pathogens to enter the brain, given its direct anatomical connection and its involvement in the early stages of Alzheimer’s disease.
While the link between nose picking and Alzheimer’s disease remains unproven, researchers say the hypothesis warrants further investigation. They also suggest that basic hygiene practices, such as regular handwashing, may help reduce potential risks.
