Research controls interrogate newly published studies and how they are reported in the media. The analysis is carried out by one or more academics who are not involved in the study, and is reviewed by another to make sure it is accurate.
No matter your age, we all pick our noses.
However, if exciting headlines around the world are any indication, this habit could increase your risk of Alzheimer’s disease, the most common form of dementia.
An international news report said:
‘SCARING EVIDENCE’ How a common habit could increase your risk of Alzheimer’s and dementia
Other ran with:
Risk of Alzheimer’s disease increases when picking your nose and hair, study warns
An Australian news article I couldn’t resist a play on words:
Can nose picking cause dementia? Australian investigators are investigating.
However, if we look at the research study behind these news reports, we may not have to worry so much. The evidence linking nose picking to dementia risk is still inconclusive.
What prompted these headlines?
Queensland researchers published your study in February 2022 in the journal Scientific Reports.
However, the results were not widely reported in the media until about eight months later, after a Press release from Griffith University in late October.
The press release had a headline similar to the multiple news articles that followed:
New research suggests nose picking may increase risk of Alzheimer’s and dementia
The press release clearly stated that the research was done on mice, not humans. But it did cite one researcher who described the evidence as “potentially frightening” to humans as well.
What the studio did
The researchers wanted to learn more about the role of chlamydia pneumonia bacteria and Alzheimer’s disease.
This species of bacteria can cause respiratory infections such as pneumonia. Not to be confused with the Chlamydia species that causes sexually transmitted infections (that’s C.trachomatis).
The researchers were interested in knowing where C pneumoniae was, how quickly it traveled from the nose to the brain, and whether the bacteria would create a hallmark of Alzheimer’s disease found in brain tissue, amyloid β protein.
So they did a little study on mice.
The researchers injected C pneumoniae in the noses of some mice and compared their results with other mice given a dose of salt water instead.
They then waited one, three, seven or 28 days before sacrificing the animals and examined what was going on in their brains.
What the study found
As expected, the researchers detected more bacteria in the part of the brain closest to the nose in the mice that received the infectious dose. This was the olfactory brain region (involved in the sense of smell).
Mice that had the bacteria injected into their noses also had clumps of β-amyloid protein around the bacteria.
Mice that did not receive the dose what’s more they had the protein present in their brains, but it was more spread out. The researchers did not compare which mice had more or less protein.
Finally, the researchers found that genetic profiles related to Alzheimer’s disease were more abundant in mice 28 days after infection compared to seven days after infection.
How should we interpret the results?
The study doesn’t actually mention nose picking or plucking nose hairs. But the press release quoted one of the researchers saying this was not a good idea as this could damage the nose:
If you damage the lining of your nose, it can increase the number of bacteria that can enter your brain.
The press release suggested that you could protect your nose (by not picking) and thus reduce your risk of Alzheimer’s disease. Once again, this was not mentioned in the study itself.
At best, the study results suggest infection by C pneumoniae it can spread rapidly to the brain, in mice.
Until we have stronger, more definitive studies in humans, I’d say the link between nose picking and dementia risk remains low. –Joyce Siette
Blind peer review
Nose picking is a common human practice throughout life. Nine out of ten people admit having done it.
At the age of 20, about 50% of people have evidence of C pneumoniae in his blood. That rises to 80% in people ages 60 to 70.
But are these factors connected? Does one cause the other?
The study behind these media reports raises some interesting points about C pneumoniae in the nasal cavity and its association with β-amyloid protein deposits (plaques) in the brain of mice, not humans.
We cannot assume that what happens in mice also applies to humans, for several reasons.
Weather C pneumoniae bacteria can be more common in people with late-onset Alzheimer’s disease, the association with the distinctive amyloid plaques in the mouse study does not necessarily mean that one is the cause of the other.
The mice were also euthanized within a maximum of 28 days after exposure, well before they had time to develop any resulting disease. This isn’t likely anyway, because mice don’t get Alzheimer’s naturally.
Although mice can accumulate the plaques associated with Alzheimer’s, are not shown memory problems seen in people.
Some researchers have also argued that β-amyloid protein deposits in animals are different from those in humans, and therefore might not be suitable for comparison.
So what’s the verdict?
Risk factors for developing Alzheimer’s disease are worth investigating.
But suggest picking your nose, which introduces C pneumoniae in the body, can increase the risk of Alzheimer’s in humans, according to this study, is overreaching. –Mark Patrick Taylor