Researchers are exploring a potential but not yet fully established connection between nose-picking and a heightened risk of developing dementia. It seems that when tissue is damaged from this habit, certain harmful bacteria may gain easier access to the brain, prompting a response that resembles symptoms associated with Alzheimer’s disease.
However, there are various uncertainties in this theory, especially since the research has primarily involved mouse models rather than human subjects. Still, these findings warrant further scrutiny, as they might shed light on how Alzheimer’s develops—a topic that continues to puzzle scientists.
A 2022 study from a team at Griffith University in Australia examined a bacterium called Chlamydia pneumoniae, which can infect humans and lead to pneumonia. Interestingly, this bacterium has been found in numerous brains of individuals suffering from late-onset dementia.
The study showed that in mice, the bacteria can ascend the olfactory nerve, which connects the nasal cavity to the brain. Additionally, when there is damage to the nasal lining, the resulting infections appear to worsen. This escalated infection leads to greater deposits of amyloid-beta protein in the brain—a protein linked with Alzheimer’s in humans.
“We’re the first to demonstrate that Chlamydia pneumoniae can enter through the nose and directly reach the brain, causing changes reminiscent of Alzheimer’s,” noted neuroscientist James St John from Griffith University at the time of the study’s release.
The speed at which C. pneumoniae infiltrates the central nervous system in mice was quite surprising; the infection occurred within just 24 to 72 hours. It seems that bacteria and viruses might see the nasal passage as a quick route to the brain.
While it remains unclear if humans would experience similar effects, or if amyloid-beta plaques truly lead to Alzheimer’s, investigating such promising leads is crucial in understanding this pervasive neurodegenerative disease.
St John emphasized the need for further studies in humans to determine whether this pathway behaves similarly. He pointed out that while many have theorized this connection, it has yet to be fully explored. What is known, though, is that these bacteria exist in humans, but how they reach the brain is still unclear.
Nose-picking is far from uncommon—some estimates suggest up to 90% of people engage in this habit, with various species also doing so, although some are perhaps a bit more skilled at it.
The benefits of nose-picking aren’t exactly clear, yet studies like this one prompt us to think twice before indulging in the habit. Future research on this matter in human subjects is forthcoming, but until then, St John and colleagues recommend refraining from nose-picking and hair-plucking due to the potential harm to the protective tissue in the nose.
“We shouldn’t damage the interior of our nose, as doing so may open the door for bacteria to reach the brain,” cautioned St John. One lingering question for the team to explore is whether the accumulation of amyloid-beta proteins is part of the body’s immune response that could potentially reverse once the infection subsides.
A review in 2023 further examined the idea that nose-picking may influence the risk of developing Alzheimer’s and delved into the mechanisms involved. According to this review, conducted by researchers at Western Sydney University in Australia, the olfactory system might represent a plausible entry point for pathogens given its direct anatomical connection to the brain and its involvement in the early stages of Alzheimer’s.
Of course, it’s still uncertain if this hypothetical pathway can explain the onset of Alzheimer’s in humans, but it seems wise to be cautious. “Understanding how pathogens enter through the olfactory route may offer new strategies for prevention,” stated the team.
They noted that enhancing hand hygiene might be an easy preventive measure—something emphasized during the COVID-19 pandemic. “One takeaway from COVID-19 is the importance of hand hygiene, so frequent handwashing and using sanitizers should be standard practices for those prone to nose-picking,” they suggested.
Alzheimer’s is an exceptionally complex condition, evident by the multitude of studies aimed at understanding it better. Yet, each new piece of research brings us closer to possible prevention or treatment options.
St John pointed out, “Once you hit 65, your risk increases significantly, but we’re also examining other causes, as it’s not solely age but also environmental factors that matter.” He believes bacteria and viruses play a vital role in this equation.
The study was published in Scientific Reports.
