If you hurt the inside of your nose, bacteria can easily get into your blood and go straight to your brain.

Scientists investigated what occurs when the generally harmless bacterium Chlamydia pneumoniae, which causes sinus difficulties, comes into contact with the nerve that connects the nose to the brain.

The mice study revealed bacteria in the brain within 72 hours. Within a month, the rodents got clumps of a protein plaque associated with Alzheimer’s.

“We’re the first,” adds the lead author professor James St. John, “to show that Chlamydia pneumoniae can go directly up the nose and into the brain where it can set off pathologies that look like Alzheimer’s disease.”

They add that this happened “in a mouse model, and the evidence is potentially scary for humans as well”.

Alzheimer’s disease affects more than 6 million people in the United States, with people over the age of 75 accounting for 73% of all Alzheimer’s patients.

Obesity, poor food, isolation, and lack of sleep are some of the lifestyle variables linked to Alzheimer’s disease, while the exact causes remain unknown.

The team from Griffith University put Chlamydia pneumoniae in the rodents’ olfactory canals.

This is the quickest route for an outside intruder to reach the brain and nose, as they are connected through the nasal passages.

Other harmful bacteria, including lethal brain-eating amoeba, can also enter the body through this pathway and kill the host.

The studies relied on mice since their olfactory systems are functionally and structurally similar to those of humans.

When a person becomes infected with Chlamydia pneumoniae, it often results in pneumonia, sore throats, ear infections, sinusitis, and other sinus-related conditions.

It can move from host to host through the air and spread through respiratory droplets.

The nose’s hairs and mucus act as a natural barrier, but the body also has certain built-in defenses against bacteria getting into the brain.

When someone picks their nose, they get rid of some of their body’s natural defenses.

Co-author of the study and director of the university’s Center for Neurobiology and Stem Cell Research, Professor St. John, says:

“Picking your nose and plucking the hairs from your nose are not a good idea.

“We don’t want to damage the inside of our nose and picking and plucking can do that.

“If you damage the lining of the nose, you can increase how many bacteria can go up into your brain.”

Research findings were reported in Scientific Reports.

In the study, mice whose olfactory nerves were implanted with bacteria had infections in their brains within three days.

This means that the bacteria were able to get through the “blood-brain barrier,” which is the last line of defense for the central nervous system’s immune system.

Infected mice also had damage to the nerve pathways in their brains, which could affect their ability to think, as well as early signs of Alzheimer’s within 28 days.

The same kind of amyloid beta plaques were also found in the mice’s brains.

The toxins on the brain are thought to be caused by the bacteria.

The development of this plaque is linked to Alzheimer’s.

The clumps make it hard for neurons and other parts of the cell to talk to each other and do their jobs.

Scientists from all over the world have not been able to show that these plaques are the main cause of the disease.

Over the summer, a critical 2006 University of Minnesota study linking the plaques to Alzheimer’s was also retracted after it was shown that the results were doctored.

The Griffith University team is nevertheless optimistic that they have uncovered a likely source for the mysterious condition’s genesis.

They may also have uncovered that the nose’s natural defensive systems are more important to the brain than previously thought.

According to Professor St John, his team “need to do this study in humans and confirm whether the same pathway operates in the same way.

“It’s research that has been proposed by many people, but not yet completed. What we do know is that these same bacteria are present in humans, but we haven’t worked out how they get there.”

The number of Americans with Alzheimer’s is expected to double by 2050, from 6 million to 13 million, according to the Alzheimer’s Association.

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