Griffith University
researchers have demonstrated that a bacteria can travel through the olfactory
nerve in the nose and into the brain in mice, where it creates markers that are
a tell-tale sign of Alzheimer’s disease.
The study, published in the journal Scientific
Reports, showed that Chlamydia pneumoniae used
the nerve extending between the nasal cavity and the brain as an invasion path
to invade the central nervous system. The cells in the brain then responded by
depositing amyloid beta protein which is a hallmark of Alzheimer’s disease.
Professor James St John, Head of the
Clem Jones Centre for Neurobiology and Stem Cell Research, is a co-author of
the world first research.
“We’re the first 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,” Professor St John said. “We
saw this happen in a mouse model, and the evidence is potentially scary for
humans as well.”
The olfactory nerve in the nose is
directly exposed to air and offers a short pathway to the brain, one which
bypasses the blood-brain barrier. It’s a route that viruses and bacteria have
sniffed out as an easy one into the brain.
The team at the Centre is already
planning the next phase of research and aim to prove the same pathway exists in
humans.
“We 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.”
There are some simple steps to look
after the lining of your nose that Professor St John suggests people can take
now if they want to lower their risk of potentially developing late-onset Alzheimer’s
disease.
“Picking your nose and plucking the
hairs from your nose are not a good idea”, he said.
“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.”
Smell tests may also have potential as
detectors for Alzheimer’s and dementia says Professor St John, as loss of sense
of smell is an early indicator of Alzheimer’s disease. He suggests smell tests
from when a person turns 60 years old could be beneficial as an early detector.
“Once you get over 65 years old, your risk factor goes right up, but we’re looking at other causes as well, because it’s not just age—it is environmental exposure as well. And we think that bacteria and viruses are critical.”
Journal article: https://www.nature.com/articles/s41598-022-06749-9
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