Few openly admit it, but all pick their noses. Whether you’re treasure hunting, out of irritation, boredom, or habit, it’s natural to indulge every now and then. Most start picking their fingers in the head as young children and continue to occasionally pick and wiggle as adults. But nose picking recently hit the headlines in a rather alarming and misleading way.
An Alzheimer’s study published in the newspaper scientific reports this February has generated a lot of buzz over the last week after Griffith University in Australia published a Press release linking nose picking to a risk factor for late-onset Alzheimer’s disease. The reason, both the article and one of the study’s authors suggested, is that a harmful bacterium chlamydia pneumonia it could travel through the nose to the brain, where it could create signs of Alzheimer’s disease. (popular science contacted the same study author for comment, but did not get a response).
Days after the initial press release, some media outlets ran fear-mongering headlines such as “nose picking can cause dementia!” and “How Nose Picking May Raise Risk of Alzheimer’s and Dementia.” But there’s a catch: The study never showed that nose picking leads to future neurodegenerative disease. Instead, it describes a map of how external pathogens might enter and infect the brain. “The study was very well done, but it’s important not to take it out of context,” he says. James Giordano, a professor of neurology and biochemistry at Georgetown University Medical Center, who was not involved in the research. “They never said in the findings that if you pick your nose, you’re going to get Alzheimer’s.” This is what the study actually found.
What was the Alzheimer’s study about “nose picking” about?
Alzheimer’s, the most common form of dementia in the US, it affects parts of the brain that control memory, often in adults older than 65. But researchers are still trying to fully understand the exact mechanisms that trigger the disease. Past studies have suggested that certain bacteria and infections may be involved in damaging the same brain areas and functions commonly associated with Alzheimer’s disease. But the evidence has not been clear..
In the February study, the authors found a potential nasal route for bacteria to reach the brain. When the olfactory mucosa, a membrane found in the upper region of the nose, is damaged, it allows invading bacteria to enter an area heavily innervated with olfactory nerve endings. The olfactory nerve controls a person’s sense of smell and is one of the shortest cranial nerves as it starts in the brain to the top roof of the nose. If the bacteria bypass the olfactory mucosa, they can travel directly to the brain. Giordano describes the journey as a “minimum toll road” to the brain, with the nasal mucosa being the only area where you are forced to stop.
“If the nasal mucosa toll booth is down, it can take the olfactory nerve highway and go up through the brain.”
The connection to Alzheimer’s is the bacterial species used in the study. chlamydia pneumoniawhich is not the same species behind the STIs, is a bacteria that causes pneumonia and has been considered as a possible contributor to Alzheimer’s disease. past investigations has found a great presence of chlamydia pneumonia in people with Alzheimer’s brains. However, few studies have shown direct evidence that the bacteria cause neurodegenerative disease.
The team observed signs that the brain was fighting an infection days after the olfactory mucosa was injured. In addition, they noted an increase chlamydia pneumonia levels, a buildup of beta-amyloid plaques (groups of proteins that can block cell signaling at synapses) in the brain, and altered genes linked to Alzheimer’s disease. The authors speculate that the bacterium infected and hid within glial cells, or non-neuronal cells, giving it time to clone itself and spread to other parts of the brain.
Although not directly studied, Giordano theorizes that the bacteria could influence the development of Alzheimer’s disease by extending the time the brain is in a pro-inflammatory state. As the brain increases inflammatory responses to fight bacterial infection, it could cause an increase in chemicals called superoxides. Superoxides alter the metabolism of brain cells, which can then produce abnormal structural and functional proteins, such as beta-amyloid and Tau—fibers that can become entangled and slow down memory recall.
Can nose picking damage your nose and trigger Alzheimer’s?
Extremely unlikely. As Giordano points out, the scientific reports study never set out to find out if chlamydia pneumonia leads to Alzheimer’s disease or dementia. Instead, their goal was to determine the likelihood that repeated intrusion of the nasal mucosa would give infectious agents the means to reach the brain via the olfactory nerve, which is a few degrees away from developing the actual condition.
“What they suggest is that people with repeated violations of the nasal mucosa have a high enough chance that bacteria and viruses will migrate to the brain and potentially activate a pro-inflammatory state, which then has the potential to induce neurodegeneration.” In other words, the study presents theoretical scenarios that explain how bacteria might trigger Alzheimer’s, but doesn’t answer whether nose picking might be a cause.
Giordano points to three other problems with drawing conclusions from this type of research. First, it only included mice. While the species is often an excellent model for studying alzheimer’s and other diseases, at a minimum, it would take 3,000 times more infectious agent damage the olfactory mucosa in a larger subject. The second problem is that the study does not address whether the human immune system is better able to respond to environmental or airborne agents that cause disease. This would mitigate any damage that pathogens might have on the nose. Lastly, the neuroscientists involved in the research did not observe the mice for hours until they picked their noses. Their experimental model involved inserting enough bacteria into the noses of mice to break down the nasal mucosa, which is not the way people naturally encounter foreign pathogens.
Does this mean you can go back to picking your nose as much as you want?
Yes, but you still want to be cautious. Sticking your fingers up your nose is not on the list of things that can cause serious injury to the nasal mucosa; It could cause more damage if you cut your nose hairs or if a foreign object gets stuck there. Still, there’s a big difference between someone who picks their nose once in a while and someone who tries their nose all the time.
If you pick your nose aggressively or with a dirty finger, you may get blood from scratching the inside of your nose. Also, frequent nose picking increases the chance of introduce or spread other types of bacteria or viruses they may try to invade your brain. This has been a concern with SARS-CoV-2, as it could directly infect the olfactory epithelium and affect a person’s sense of smell, Giordano explains. “That’s why the study is very good. He wonders if other infectious agents use similar vectors to access the brain.”
It’s a valid question to ask, and one that could perhaps lead to more targeted research on devastating diseases like Alzheimer’s. But the jump from nose picking to Alzheimer’s is too far. So for now, it’s best not to spread scary assumptions.