A surprising link between picking your nose and Alzheimer’s was found in a study with mice

link between picking your nose and Alzheimer's

A surprising link between picking your nose and Alzheimer’s was found in a study with mice

A new study found a possible but weak link between picking your nose and having a higher chance of getting dementia.

When picking your nose hurts your internal tissues, certain types of bacteria have an easier time getting to your brain. When they do, your brain reacts in ways that look like Alzheimer’s disease.


There are a lot of things that need to be taken into account, like the fact that the research so far has only been done on mice and not on humans. However, the results are interesting enough to warrant more research, and they could help us figure out how Alzheimer’s starts, which is still a bit of a mystery.

Scientists from Griffith University in Australia led a group of researchers who did tests with a bacteria called Chlamydia pneumoniae. This bacteria can infect people and cause pneumonia. The bacteria has also been found in the brains of most people with dementia that comes on later in life.


It was shown that the bacteria could move up the olfactory nerve in mice (joining the nasal cavity and the brain). Also, nerve infections got worse when there was damage to the nasal epithelium, which is the thin tissue that lines the roof of the nose.

This caused the mice’s brains to make more amyloid-beta protein, which is a protein that is made when there is an infection. People with Alzheimer’s disease also have a lot of clumps of this protein, which are called plaques.

Neuroscientist James St. John from Griffith University in Australia says, “We’re the first to show that Chlamydia pneumoniae can go straight up the nose and into the brain, where it can cause pathologies that look like Alzheimer’s disease.”


“We saw this happen in a mouse model, and the evidence suggests that it could happen to people, too.”

Scientists were surprised by how quickly C. pneumoniae infected the mice’s central nervous systems. It took only 24 to 72 hours for the infection to start. People think that bacteria and viruses use the nose to get to the brain quickly.

Even though it’s not certain that the effects will be the same in humans or that amyloid-beta plaques are a cause of Alzheimer’s, it’s important to follow up on promising leads in the fight to understand this common neurodegenerative disease.


St. John says, “We need to do this study on people to see if the same pathway works the same way.”

“Many people have thought of this research, but it hasn’t been done yet. We do know that these bacteria can be found in people, but we don’t know how they get there.”

Nose picking isn’t that uncommon. It’s possible that as many as 9 out of 10 people do it, plus a lot of other species (some a little more adept than others). Even though the benefits aren’t clear, this study should make us think twice before picking.


Human studies of the same processes are planned for the future, but until then, St. John and his colleagues say that picking your nose and plucking your nose hair is “not a good idea” because it could hurt the tissues that protect your nose.

The team will try to find out if the increased amyloid-beta protein deposits are a normal, healthy immune response that can go away when the infection is gone.

Alzheimer’s is a very complicated disease, which is clear from how many studies are being done on it and how many different ways scientists are trying to understand it. However, each study brings us closer to finding a way to stop it.


“Once you’re over 65, your risk goes way up,” says St. John. “But we’re also looking at other causes, because it’s not just age; it’s also environmental exposure, and we think that viruses and bacteria are very important.”


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


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