A study published in 2022 found a weak but plausible link between nose picking and an increased risk of developing dementia.
In cases where nose picking causes damage to internal tissues, critical species of bacteria have a clearer pathway to the brain, which responds to their presence in ways that resemble signs of Alzheimer’s disease.
There are numerous caveats here, not the least of which is that the supporting research so far is in mice rather than humans, but the findings certainly deserve further investigation—and could improve our understanding of how Alzheimer’s disease begins, which remains a mystery.
Related: Simple new compound reverses Alzheimer’s symptoms in rats
A team of researchers led by scientists from Griffith University in Australia conducted tests with a bacteria called Chlamydia pneumoniaewhich can infect humans and cause pneumonia.
C. pneumoniae it was also found in most human brains affected by late-onset dementia.
The video below contains a summary of the study’s findings:
It was shown that in mice, bacteria could travel up through the olfactory nerve (connecting the nasal cavity and the brain).
Furthermore, when there was damage to the nasal epithelium (the thin tissue along the roof of the nasal cavity), nerve infections worsened.
This caused the mouse brain to deposit more of the beta-amyloid 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 straight into the nose and into the brain, where it can trigger pathologies that look like Alzheimer’s disease,” said neuroscientist James St John of 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.”
Scientists were surprised by the speed of the chariot C. pneumoniae settled into the central nervous system of mice, infection occurred within 24 to 72 hours. Bacteria and viruses are thought to see the nose as a fast track to the brain.
While it is not certain that the effects will be the same in humans, or even that beta-amyloid plaques are a cause of Alzheimer’s disease, it is still important to follow promising leads in the fight to understand this common neurodegenerative condition.
“We need to do this study in humans and confirm whether the same pathway works in the same way,” St John said.
“It’s research that’s been proposed by many people but hasn’t been completed yet. What we do know is that the same bacteria are present in humans, but we haven’t determined how they get there.”
Related: Nasal spray may slow Alzheimer’s disease, study in mice suggests
Picking the nose is not exactly a rare thing. In fact, it’s possible that up to 9 out of 10 people do it…not to mention a bunch of other species (some a little more adept than others).
Although the benefits are not clear, studies like this should give us pause before choosing.
Future studies of the same processes in humans are planned – but until then, St John and his colleagues suggest that picking your nose and pulling your nose hair is “not a good idea” because of the potential damage it causes to the nose’s protective tissue.
“We don’t want to damage the inside of our nose, and picking and plucking can do that,” St John warned.
“If you damage the lining of the nose, you can increase how much bacteria can get into the brain.”
An outstanding question the team will seek to answer is whether or not the increased deposits of beta-amyloid protein are a natural, healthy immune response that can be reversed when the infection is fought.
A 2024 review further advanced the hypothesis that nose picking could play a role in increasing the risk of developing Alzheimer’s disease – revealing more about how the process might play out.
Related: Alzheimer’s Cause May Come From Inside Your Mouth
Alzheimer’s is an incredibly complicated disease, as evidenced by the sheer number of studies into it and the many different angles scientists are taking in trying 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 also looking at other causes, because it’s not just age, it’s also environmental exposure,” St John said.
“And we think bacteria and viruses are critical.”
The research was published in Scientific reports.
An earlier version of this article was published in November 2022.