A study published in 2022 found a slight but plausible link between picking your nose and an increased risk of developing dementia.
In cases where the collection from your nose causes damage to internal tissues, critical species of bacteria have a clearer path to the brain, which responds to their presence in ways that resemble signs of Alzheimer’s disease.
There are several caveats here, not the least of which is that the supporting research so far is in mice rather than humans, but the findings are certainly worth further investigation – and may improve our understanding of how Alzheimer’s disease begins, which remains something of a mystery.
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A team of researchers led by scientists from Griffith University in Australia did tests with a bacterium called Chlamydia pneumoniaewhich can infect humans and cause pneumonia.
C. pneumoniae it has also been discovered in the majority of human brains affected by late-onset dementia.
The video below summarizes the study’s findings:
It has been shown that in mice, bacteria can travel in the olfactory nerve (connects to the nasal cavity and the brain).
In addition, when there was damage to the nasal epithelium (the thin tissue along the roof of the nasal cavity), the nerve infections got worse.
This caused the mouse brains to deposit more of the amyloid-beta protein – a protein that is released in response to infections.
Plaques (or clumps) of this protein are also found in significant concentrations in people with Alzheimer’s disease.
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“We are the first to show this Chlamydia pneumoniae it can go up directly into the nose and brain where it can trigger pathologies similar to Alzheimer’s disease,” said neuroscientist James St John from Griffith University in Australia, when the study was published in October 2022.
“We’ve seen this happen in a mouse model, and the evidence is potentially scary for humans as well.”
The scientists were surprised by the speed with which C. pneumoniae took hold in the central nervous system of mice, with infection occurring within 24 to 72 hours. It is believed that bacteria and viruses see the nose as a quick route to the brain.
While it is not certain that the effects will be the same in humans, or even that amyloid-beta plaques are a cause of Alzheimer’s, it is nevertheless important to follow promising results in the fight to understand this common neurodegenerative condition.
“We want to do this study in humans and confirm if the same pathway operates in the same way,” said San Gwann.
“It is research that has been proposed by many people, but it has not yet been completed. What we know is that these same bacteria are present in humans, but we have not worked out how they get there.”
Related: Nasal Spray May Suppress Alzheimer’s Disease, Mice Study Suggests
Nose picking isn’t exactly uncommon. In fact, it is possible that 9 out of 10 people do this… not to mention a bunch of other species (some a little more adept than others).
While the benefits are unclear, studies like this should give us pause before we gather.
Future studies on the same processes in humans are planned – but until then, San Juan and his colleagues suggest that picking your nose and plucking your nose hair is “not a good idea” because of the potential damage it does to the nose’s protective tissue.
“We don’t want to damage the inside of our nose and picking and plucking can do that,” warned San Ġwann.
“If you damage the lining of the nose, you can increase how much bacteria can get into the brain.”
One outstanding question the team will be looking to answer is whether the increase in amyloid-beta protein deposits are a natural and healthy immune response that can be reversed when the infection is fought.
A 2024 review further advanced the hypothesis that nose picking may play a role in increasing the risk of developing Alzheimer’s disease – revealing more about how the process may occur.
Related: The Cause of Alzheimer’s May Be Coming From Inside Your Lips
Alzheimer’s is an incredibly complicated disease, as is clear from the large number of studies about it and the many different angles that scientists are taking to try to understand it – but each piece of research brings us a little closer to finding a way to stop it.
“Once you’re over 65, your risk factor goes up, but we’re looking at other causes as well, because it’s not just age – it’s also environmental exposure,” said St John.
“And we think that bacteria and viruses are critical.”
The research was published in Scientific Reports.
An earlier version of this article was published in November 2022.