Oral hygiene habits have been drilled into us from an early age – we must brush our teeth twice a day, and ideally floss. The given reasons (everything from avoiding stinky breath to the threat of a painful dentist visit) make a pretty compelling argument.
Despite this, the oral health of the nation is not in good shape. Gingivitis – the precursor to gum disease – affects most adults in the UK to some degree at some point, while one study found that only 17 per cent of UK adults did not have any sign of gum disease. And the consequences can be more significant than a bleeding gum or a steep dentist’s bill.
Alzheimer’s is the most common cause of dementia and accounts for around six in every 10 cases of dementia. It was the leading cause of death in the UK in 2022, and affects around 940,000 people in the UK. That number is expected to rise to over one million by 2030.
There are several lifestyle behaviours thought to increase the risk of Alzheimer’s, including smoking, drinking, hypertension and high cholesterol. And there is increasingly, strong evidence that a potential cause of developing Alzheimer’s disease can be found in unhealthy gums.
Jing Kang is a senior lecturer in medical statistics at King’s College, London researching the connection between oral health and Alzheimer’s. She says there seems to be a bi-directional relationship between our mouths and our brains.
On the one hand, maintaining good oral health can be a significant challenge for people with Alzheimer’s, with dementia inadvertently leading to gum disease and tooth loss. And on the other hand, she says, “gum disease or having painful, bleeding gums has been linked to a higher chance of onset of dementia. There is scientific evidence showing one type of bacteria that is commonly found in people who have gum disease (Porphyromanos gingivalis), has recently been found in the brains of Alzheimer’s patients.”
If you don’t take care of your teeth, the small gap between the tooth and gum can widen as bacteria builds up. This causes increasing inflammation, eventually leading the gum to pull further away from the tooth. And in this gap, it’s thought that the bacteria can enter our bloodstream, eventually travelling to, and perhaps damaging, the brain.
Alzheimer’s involves the accumulation of misfolded proteins called amyloid plaques, which are associated with cell death and cognitive decline. There are specific cells that are responsible for fighting off amyloid plaque but the bacteria in gum disease seems to inhibit the body’s ability to do so. “The damage in the brain might be caused by the gum bacteria, and it’s possibly connected to memory loss or cognitive decline,” adds Kang. “As it is accumulated over time it could lead to the onset of dementia.”
Different studies have found other connections between periodontitis and Alzheimer’s. One found that people with fewer than 10 teeth have a smaller brain region that is critical for memory, suggesting tooth loss may precede development of dementia. And studies have reported lower odds of people developing Alzheimer’s disease when patients with frequent gum disease had their oral infection treated, though their risk would increase if they exceeded four extractions. This suggests chronic inflammation in particular increased the risk of Alzheimer’s.
Kang also points to additional studies where people who have gum disease are treated and then their cognitive function is measured over the years afterwards. “Some have shown a slower rate of cognitive decline compared with people who have gum disease but did not receive treatment. The scale of the study is quite small (these kinds of clinical studies take a long time and are very costly) but there is data and evidence showing that treating gum disease at an early stage reduces the rate of cognitive decline.”
More data is required before anyone can conclusively say that taking care of your oral health can prevent dementia. But scientists, including Kang, think that protecting your oral health as a preventative measure is a very good idea.
“People are still investigating how it works biologically, but if we say our hypothesis is that the bacteria from the mouth can penetrate the gum and travel through the whole body and reach parts of the brain, then stopping the bacteria from entering the gum by keeping good hygiene would reduce the risk of dementia later in life.”
Plus, there is a risk of other chronic, degenerative or even fatal diseases if you don’t take care of your oral health. Gum disease can increase your risk of diabetes, rheumatoid arthritis, heart disease and respiratory diseases.
How to stop gum disease
“Prevention is key when it comes to reducing the chance of the Porphyromonas gingivalis bacteria growing within oral cavities,” explains Dr Smita Mehra, principal dentist at The Neem Tree Dental Practice.
This means going for regular dental check-ups and trips to the hygienist, as well as developing consistent oral hygiene habits. “Small steps like brushing your teeth twice a day, having regular dental check-ups, flossing, and treating gum disease as early as possible will all make a huge difference later in our life” adds Kang.
This will also help reduce the number of tooth extractions, which could be key in preventing the development of Alzheimer’s.
“Clinicians must have conversations with patients about the benefits of good oral hygiene practices as well as the importance of retaining as many natural teeth as possible as they age,” explains Shalini Kanagasingam, specialist endodontist and clinical lecturer at the University of Central Lancashire.
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