Written by Viva Voong '26
Edited by Evan MacLure '26
Ninety one percent of the population reports picking their noses. You may have heard that nose picking introduces viruses, bacteria, and other contaminants into the nose. Many people are also aware that nose picking spreads bacteria and viruses from the nose onto surfaces in the environment and damages the tissues and structures inside the nose. A recent mouse study conducted by Griffith University and the Clem Jones Center for Neurobiology and Stem Cell Research in Queensland, Australia shows that this common habit can be linked to an increased risk for neurodegenerative diseases, such as Alzheimers and dementia.
How do bacteria and other particles reach the brain? First, an abundance of bacteria, viruses, dust, dirt and other airborne particles can enter the nasal cavity every time we breathe. Hairs and mucus attempt to trap these particles and prevent them from moving past the nasal cavity. However, some particles bypass these protective mechanisms and make their way towards the olfactory nerves; these nerves form the shortest nerve in the head and give people a sense of smell. Particles subsequently move through the olfactory bulb to the olfactory tract as shown in the diagram above. Finally, they enter the brain, where they have the potential to influence neurological processes and functions. This pathway is significant because it allows bacteria to bypass the blood-brain barrier (BBB) and directly enter the brain. Upon entering the brain, these bacteria can lead to the deposition of proteins associated with Alzheimer’s disease.
Chlamydia pneumoniae is a bacteria linked to pneumonia, among other respiratory diseases. In this study, it takes 72 hours for C. pneumoniae to travel up the nerves and infect the brain. At the 7th and 28th day mark, mice displayed “dysregulation of key pathways involved in Alzheimer’s.” In vitro studies indicated that C. pneumoniae was able to infect the peripheral nerve and glia.
Peripheral nerves. The body consists of two nervous systems: the central nervous system and the peripheral nervous system. The central nervous system includes the brain and the spinal cord, while the peripheral nervous system includes the nerves that connect the brain and spinal cord to the rest of the body.
Glia. The brain includes neurons and glia. The main function of a neuron is to send and receive signals, while glia serve to protect neurons.
The researchers at Griffith University believe that C. pneumoniae can affect the central nervous system by surviving in glia and causing beta-amyloid deposition. This interferes with the function of the endoplasmic reticulum in cells, affecting protein production and proper folding.
The results of this study suggest that nose picking damages the lining of the nose, allowing C. pneumoniae to travel through the olfactory pathway and enter the brain. Upon its arrival, C. pneumoniae causes the deposit of the beta-amyloid protein, which is a sticky compound associated with Alzheimer’s disease. The beta amyloid hypothesis states that Alzheimer’s disease is caused by a build up of multiple substances in the brain. Normally functioning tau proteins are involved in maintaining cell structure through the stability of microtubules, a component of a cell’s cytoskeleton. Tau proteins involved with Alzheimer’s disease cause filaments to build up and form “tangles” in neurons. This causes the formation of plaques around neurons. These “plaques” contain beta-amyloid peptides, which are adhesive substances that interfere with normal brain processes and function.
James St. John, a co-author of this study, is excited about the new research questions this study can inspire. According to St. John, the next step in this research is to prove that this pathway exists in humans. St. John believes it is important for people to avoid habits that can potentially damage the lining of the nose. In the future, he is interested in conducting research on whether smell tests can be an indicator of the onset of Alzheimer’s.
In conclusion, a recent study has shown a possible association between nose picking and the onset of Alzhemier’s disease through the damaging of nose tissues and transport of bacteria into the brain. Although causation cannot be concluded without further research, this study allows scientists to consider less expected causes of Alzhiemer’s. In addition, it opens many doors of possibilities in Alzheimer’s research. Creative ideas based upon prior research can help neuroscientists reach new frontiers in the cutting edge research they diligently conduct everyday.
References
Chacko A, Delbaz A, Walkden H, Basu S, Armitage CW, Eindorf T, et al. Chlamydia pneumoniae can infect the central nervous system via the olfactory and trigeminal nerves and contributes to Alzheimer’s disease risk. Scientific Reports [Internet]. 2022 Feb 17;12(1):2759. Available from: https://www.nature.com/articles/s41598-022-06749-9#citeas
Archive VA, feed G author R. How picking your nose could increase risk of Alzheimer’s and dementia [Internet]. New York Post. 2022. Available from: https://nypost.com/2022/10/31/how-picking-your-nose-could-increase-risk-of-alzheimers/
News N. Nose Picking Could Increase Risk for Alzheimer’s and Dementia [Internet]. Neuroscience News. 2022 [cited 2023 Apr 10]. Available from: https://neurosciencenews.com/olfaction-nose-alzheimers-21742/
Nield D. Mouse Study Suggests a Surprising Link Between Nose-Picking And Alzheimer’s [Internet]. ScienceAlert. 2022. Available from: https://www.sciencealert.com/mouse-study-suggests-a-surprising-link-between-nose-picking-and-alzheimers
Alzheimer’s and dementia: How picking your nose may increase your risk [Internet]. www.medicalnewstoday.com. 2022. Available from: https://www.medicalnewstoday.com/articles/picking-your-nose-may-increase-alzheimers-dementia-risk
Nose picking: Why people do it and how to stop [Internet]. www.medicalnewstoday.com. 2020. Available from: https://www.medicalnewstoday.com/articles/nose-picking