How dental health may impact brain health; experts describe how poor oral hygiene is linked to higher risk of developing dementia

Bad dental hygiene could affect your mental health in the future, according to a study that says the risk of Alzheimer’s is 21 per cent higher in people with poor hygiene and gum disease. Photo: Professor Nicola West A build-up of plaque and tartar on teeth creates a breeding ground for bacteria that can lead to gum disease – and inflammation that can affect the brain

People with poor dental hygiene are 21 per cent more likely to develop Alzheimer’s disease, a recent study suggests, so regular flossing and brushing are vital

Listen to this article

This is the 31st instalment in a series on dementia , including the research into its causes and treatment, advice for carers, and stories of hope.

In a photograph of my mother on my desk, she is smiling broadly, an even, white-toothed smile. It was taken 18 months before she died. Her dementia was evident everywhere in our lives by then – but not in that picture: from the photo you’d never guess. She looks self-possessed and whole. In fact, she looks like a commercial for geriatric dental care with that wide, white smile.

I wish she’d always had teeth like that; she used to be very conscious of her smile when she had her own teeth. Two years before the photo in question, she’d had her top teeth removed, all of them. They were loose and discoloured. Her “falsies” transformed her face.

What I never imagined was that those teeth might have been another marker, another risk factor, for the dementia later. Anthea Rowan’s mother pictured 18 months before she died. She wore dentures after her own teeth were removed. Photo: courtesy of Anthea Rowan Nicola West is a professor of periodontology and head of the Clinical Trials Unit at the School of Oral and Dental Sciences at the UK’s University of Bristol. Her team’s recent MySmile study into this connection was prompted when links between Alzheimer’s disease and gum disease began to stack up.

Oral health – that is, the state of your teeth and gums – is linked to more than just fillings and dentures. West says poor oral health is associated with many common diseases, including cardiovascular disease , neurodegenerative diseases, diabetes and rheumatoid arthritis.

Dentist Dr Raymond Lee at Pacific Dental and Orthodontic Care in Hong Kong stresses that good oral care isn’t just about supporting teeth and gum health.

“It influences our overall physical well-being,” he says. How? The mouth is connected to important systems – respiratory, digestive and cardiovascular – and contains numerous bacteria and microorganisms, some of which can harm our health.

Our body’s defence system usually keeps these in check. But, if we don’t brush and floss regularly, if we ignore oral health, a build-up of plaque and tartar on our teeth creates a breeding ground for bad bacteria which can lead to gum disease, Lee says. Good teeth and gum health support overall physical well-being, says Hong Kong dentist Dr Raymond Lee. Photo: Dr Raymond Lee There are two types: gingivitis, which affects only the soft gum and is reversible, and periodontitis (symptoms include bad breath, loosening teeth and painful chewing), which is “an advanced form of gum disease that can’t be reversed – the damage to the bone and gum tissue is permanent leading to tooth loss”.

Every Friday

Discover news and insights on women trailblazers, social issues and gender diversity in Asia

By submitting, you consent to receiving marketing emails from SCMP. If you don’t want these, tick here

By registering, you agree to our T&C and Privacy Policy

Part of what explains the close link between oral health and whole body health lies in the body’s immune system, he explains, which responds to damage or disease by inflammation.

“Inflammation can help the body heal – but if it persists, it can become chronic and lead to more severe problems. Periodontal disease, diabetes, heart disease, respiratory infections and dementia are all diseases associated with an inflammatory response.” What is inflammation? Causes, symptoms, and treatment for chronic cases25 May 2022

What happens, explains West, is that the build-up of disease-causing bacteria (pathogens) within infected gums – even if the patient is unaware of this infection – may overwhelm and travel through blood vessels infecting and triggering inflammation in the bloodstream and other body tissues, including in the brain, which is situated very close to the teeth and gums and “has direct routes to them”, West says.

According to one study, losing a tooth is linked to an extra year of brain ageing, while severe gum disease is linked to 1.3 years of brain ageing. Professor Nicola West led the team that conducted the recent MySmile study into the links between gum disease and Alzheimer’s disease. Photo: University of Bristol Dental School Although the precise relationship between poor dental health and loss of brain volume is unclear, says Lee, research in Finland shows that people with poor dental hygiene are 21 per cent more likely to develop Alzheimer’s disease.

Other studies have identified a bacteria called Porphyromonas gingivalis which is involved in periodontal disease. This and the enzyme it produces (gingipains) present as strong risk factors for Alzheimer’s disease. Both can cross the blood-brain barrier, says Lee, “and both were found in the brain tissue of people suffering from Alzheimer’s”.

Researchers at the School of Dentistry at the University of Central Lancashire in the UK found that when the gingipains enzyme interacts with nerve cells in the brain, “it releases a protein that causes the cell to self-destruct, leading to cell death.

“Once the nerve cell dies, the protein may attach itself to healthy neighbouring nerve cells, repeating the process and causing further damage to the brain as the disease spreads.” ‘I’ll swallow my toothache’: Hong Kong’s dentist shortage leaves poor without care15 Apr 2023

Alzheimer’s is linked to a build-up of amyloid-beta protein in the brain. Lee says researchers have identified that amyloid-beta protein is abundant around the surfaces of infected teeth and diseased gums.

“The suggestion is these proteins may filter into the bloodstream and […]

Read more at www.scmp.com