A 2022 study found a tenuous but plausible link between picking your nose and increasing your risk of developing dementia.
In cases where scratching the nose damages internal tissues, critical species of bacteria gain an easier path to the brain, which reacts to the presence of the bacteria in a way that resembles signs of Alzheimer’s disease.
There are plenty of caveats here, including that the supporting research so far has been mouse-based rather than human-based, but the results certainly merit further investigation – and could improve our understanding of how from which Alzheimer’s disease starts, a process that remains something of a mystery.
A team of researchers led by scientists from Griffith University in Australia carried out tests with a bacterium called Chlamydia pneumoniae, which can infect humans and cause pneumonia. The bacterium has also been found in the majority of human brains affected by late onset dementia.
It has been shown that in mice, the bacteria can move up the olfactory nerve (joining the nasal cavity and the brain). Also, when there was damage to the nasal epithelium (the thin tissue along the roof of the nasal cavity), nerve infections worsened.
This led the mice’s brains to deposit more beta-amyloid protein, a protein that is released in response to infections. Plaques (or clumps) of this protein are also found in high concentrations in people with Alzheimer’s disease.
“We are the first to show that Chlamydia pneumoniae can go straight up into the nose and into the brain where it can trigger pathologies that resemble Alzheimer’s disease,” neuroscientist James St John of Griffith University in Australia said in a 2022 statement.
“We’ve seen this happen in a mouse model, and the evidence is potentially frightening for humans as well.”
Scientists were surprised by the speed at which C. pneumoniae settled in the central nervous system of mice, with infection occurring within 24 to 72 hours. Bacteria and viruses are thought to see the nose as a fast track to the brain.
Although it is not certain that the effects are the same in humans, or even that amyloid-beta plaques are the cause of Alzheimer’s disease, it is nevertheless important to follow promising leads in the struggling to understand this common neurodegenerative condition.
“We need to do this study in humans and confirm if the same pathway works the same way,” St John said.
“This is research that has been proposed by many people, but has not yet been completed. What we know is that these same bacteria are present in humans, but we have not understood how they get there.”
Nose picking isn’t 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 bit more adept than others). Although the benefits are unclear, studies like this should give us pause before deciding.
Future studies of the same processes in humans are planned – but until then St John and colleagues suggest nose picking and nose hair removal are ‘not a good idea’ due to the damage potentials this causes to the protective tissue of the nose.
One open question the team will seek to answer is whether increased amyloid beta protein deposition is a natural and healthy immune response that can be reversed when the infection is fought.
Alzheimer’s disease is an incredibly complicated disease, as evidenced by the sheer number of studies on it and the many different angles scientists take to try to understand it – but each research brings us one step closer to finding Alzheimer’s disease. 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.
“And we think bacteria and viruses are essential.”
The research has been published in Scientific reports.
A version of this article was first published in November 2022.