Picking your nose may raise the risk of dementia, a study suggests.
Damaging the inside of the nostrils creates a shortcut for bacteria to seep into the blood and travel directly to the brain.
Researchers looked at what happens when the nerve that connects the nose to the brain is exposed to Chlamydia pneumoniae, a normally harmless bug that causes sinus issues.
The study — on mice — found detectable levels of the bacteria in the brain within 72 hours.
Within a month, the rodents developed clumps of a protein plaque linked to Alzheimer’s.
Lead study author Professor James St John, from Griffith University in Australia, said: ‘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.
‘We saw this happen in a mouse model, and the evidence is potentially scary for humans as well.’
More than 6million Americans suffer from Alzheimer’s, with 73 per cent of people suffering from the disease being over 75.
In the UK, over 900,000 people have a confirmed case of dementia – of which Alzheimer’s is the leading cause.
The causes of Alzheimer’s are still unknown, but obesity, a poor diet, loneliness and a lack of sleep are all among the many lifestyle factors tied to the disease.
Picking your nose removes mucus and hair, which serve as part of the body’s defense system against bacteria and other bad actors (file photo)
Researchers exposed mice to Chlamydia pneumoniae via their olfactory nerve to see if the bacteria would travel all the way to the brain, and what affects it would have once it was there
Pictured: The peripheral and olfactory nerves of the mice were infected by the bacteria within a few hours. On the left, three days into the study, the nerves from a mouse in the control group are unaffected. On the right, there is infection visible (green)
The team at Griffith University exposed the rodents to Chlamydia pneumoniae through their olfactory canal.
This is the pathway between the brain and the nose – and the fastest way for an invader from outside body to get into the central nervous system.
Highly deadly brain eating amoeba, among other dangerous bacteria, also enter the body and cause harm through this pathway.
Mice were chosen for the research because their olfactory system functions and is structured similarly to that of humans.
What is Alzheimer’s?
Alzheimer’s disease is a progressive, degenerative disease of the brain, in which build-up of abnormal proteins causes nerve cells to die.
This disrupts the transmitters that carry messages, and causes the brain to shrink.
More than 5 million people suffer from the disease in the US, where it is the 6th leading cause of death, and more than 1 million Britons have it.
As brain cells die, the functions they provide are lost.
That includes memory, orientation and the ability to think and reason.
The progress of the disease is slow and gradual.
On average, patients live five to seven years after diagnosis, but some may live for ten to 15 years.
- Loss of short-term memory
- Behavioral changes
- Mood swings
- Difficulties dealing with money or making a phone call
- Severe memory loss, forgetting close family members, familiar objects or places
- Becoming anxious and frustrated over inability to make sense of the world, leading to aggressive behavior
- Eventually lose ability to walk
- May have problems eating
- The majority will eventually need 24-hour care
Source: Alzheimer’s Association
Chlamydia pneumoniae is a common bacteria that causes pneumonia, sore throats, ear infectious, sinusitis and other sinus related issues when a person is infected.
It can spread through respiratory droplets and travel from host-to-host through the air.
The body has some built in mechanisms to prevent the bacteria from entering the brain, though, like hairs and mucus in the nose that serve as a natural barrier.
When a person is picking their nose they remove some of those natural defenses.
Professor St John, co-author of the study and head of the school’s Center for Neurobiology and Stem Cell Research, added:
‘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.’
The results were published in the journal Scientific Reports.
In the study, mice who had the bacteria implanted into their olfactory nerves had their brains infected within 72 hours.
This means the bacteria was able to cross the ‘blood brain barrier’ – the final immune defense for the body’s central nervous system.
Infected mice also showed damage to their brain’s neural pathways that could affect their cognitive function, along with early development of Alzheimer’s within 28 days.
The formulation of amyloid beta plaques were detected on the brains of the mice as well.
It is believed that the bacteria triggers the toxins to form on the brain.
One of the leading theories on the development of Alzheimer’s is tied to the development of this plaque.
The clumps block and disrupt communication between neurons and other cell functions.
Scientists around the world have not been able to prove that these plaques are at the center of the disease’s formation.
A key 2006 University of Minnesota study tying the plaques to Alzheimer’s was also retracted over summer after it was revealed the results were doctored.
Still, Griffith University researchers are hopeful that they have found a potential source for how the perplexing condition forms.
They also may have discovered that the nose’s inherent defense systems are more valuable to the brain than previously believed.
Professor St John said 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 Alzheimer’s Association reports that the 6million Americans living with Alzheimer’s is expected to double to 13million by 2050.
One-in-three seniors will die of Alzheimer’s.