Mouse study reveals surprising connection between nose-picking habit and Alzheimer's disease - Video

It's a habit most people don't think twice about, but picking your nose might do more than irritate your nasal passages. A 2022 study from Griffith University in Australia, published in Scientific Reports, uncovered a possible connection between nose picking and dementia risk, specifically Alzheimer’s disease. While the findings come from studies in mice, they raise important questions about how bacteria entering through the nose could reach the brain and trigger early processes linked to neurodegeneration.

Alzheimer’s is characterized by the buildup of amyloid beta plaques in the brain, clumps of protein long associated with memory loss and cognitive decline. The Australian research team, led by neuroscientist Dr. James St John, focused on how infection and inflammation might contribute to this process. Using a mouse model, they introduced a bacterium known as Chlamydia pneumoniae—the same species that causes pneumonia in humans—and tracked its movement through the nasal cavity.

What they found was unsettling: within 24 to 72 hours, the bacteria migrated directly from the nasal passages up the olfactory nerve into the brain, where they triggered immune responses and increased deposits of amyloid beta protein. Damage to the nasal lining made this invasion much easier. When the delicate nasal epithelium was injured — something that can happen through frequent nose picking or plucking nose hairs — the infection spread more quickly and caused heavier plaque accumulation in the mouse brains.

Dr. St John suggests this mechanism could help explain how infections act as environmental triggers for neurodegenerative diseases. The researchers emphasized, however, that the work was done in animals, and similar effects in humans still need to be confirmed.

Follow up studies will aim to test whether the same pathway exists in people and whether amyloid beta buildup in this context represents a harmful process or a protective immune response. Until then, experts advise minimizing injury to the nasal lining.

While more research is needed, the message is clear: the humble nose may hold unexpected clues to how Alzheimer’s begins — and perhaps how to prevent it.

REFERENCE: Chacko, A., Delbaz, A., Walkden, H. et al. Chlamydia pneumoniae can infect the central nervous system via the olfactory and trigeminal nerves and contributes to Alzheimer’s disease risk. Sci Rep 12, 2759 (2022). https://doi.org/10.1038/s41598-022-06749-9