Our nose does far more than help us smell flowers, food, or fresh air. It may also act as a hidden doorway into the brain.
A new study from Griffith University has found that certain bacteria can travel directly from the nose into the brain, possibly setting off changes linked to Alzheimer’s disease.
This discovery gives scientists a new way of thinking about how infections might influence this serious condition.
The research was led by Professor James St John and published in Scientific Reports. His team focused on a type of bacteria called Chlamydia pneumoniae. Most people know this bacteria for causing lung infections, sinus infections, or other respiratory problems.
But the researchers found something unexpected. They discovered that the bacteria can move through the olfactory nerve, which is the nerve responsible for helping us smell.
This nerve is unusual because it is directly exposed to the outside environment. Most of the brain is protected by the blood-brain barrier, which works like a security system to keep harmful things out. But the olfactory nerve bypasses this barrier, which means it provides a shortcut straight into the brain.
To explore this pathway, the scientists carried out experiments on mice. They introduced the bacteria into the nose and found that it traveled along the olfactory nerve and entered the brain. Once inside, the presence of the bacteria triggered the brain to produce amyloid beta, a sticky protein that is strongly linked to Alzheimer’s disease.
These proteins can clump together over time and form plaques. Many experts believe these plaques interfere with how brain cells communicate, eventually causing memory loss and other symptoms of Alzheimer’s.
One surprising part of the study involved everyday habits like picking your nose or plucking nose hairs. These actions can damage the delicate lining inside the nose. When this lining is damaged, it becomes easier for harmful bacteria to enter the body.
The research team warns that if bacteria gain access more easily, they might be more likely to reach the brain. This may increase the risk of developing long-term brain problems.
Another interesting point relates to smell. Losing the sense of smell is one of the earliest signs of Alzheimer’s disease. It often shows up years before memory problems begin.
Because of this, the researchers suggest that simple smell tests starting around age 60 could help detect early brain changes. If someone begins losing their sense of smell unexpectedly, it might be a clue that something is happening inside the brain.
Although the current study was done on mice, the researchers are already planning to study humans to see if this direct infection pathway also exists in people.
If they confirm it, this discovery could lead to new ways to detect, prevent, or treat Alzheimer’s disease. For example, doctors might eventually be able to treat infections in the nose to protect the brain or create new tests based on smell loss.
For now, people can take simple steps to protect their nose and possibly reduce risk. Avoid picking your nose or plucking nose hairs, as these habits can harm the sensitive inner lining. Keeping the nasal passages healthy may help prevent bacteria from traveling where they do not belong.
This study offers a fascinating look at how our sense of smell, infections, and brain health are connected. It opens the door to new possibilities for early detection of Alzheimer’s and reminds us that small everyday habits—even involving the inside of our nose—can play a role in long-term brain health.
If you care about Alzheimer’s disease, please read studies that bad lifestyle habits can cause Alzheimer’s disease, and strawberries can be good defence against Alzheimer’s.
For more information about brain health, please see recent studies that oral cannabis extract may help reduce Alzheimer’s symptoms, and Vitamin E may help prevent Parkinson’s disease.
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