Could gum disease and poor dental health be an early sign of Alzheimer's disease?
- - Bugs that cause gum disease were found in brains of dementia patients
- - These bugs can enter the bloodstream through eating and dental surgery
- - From there scientists claim they can enter the brain and destroy neurons
By ELLIE ZOLFAGHARIFARD and JENNY HOPE
Bad teeth and gum disease could be linked to Alzheimer’s, say scientists.
The bacteria caused by poor oral hygiene can kill off nerve cells once they reach the brain, causing the confusion and memory loss associated with dementia.
Researchers who examined the brains of ten dead Alzheimer’s patients found signs of the bug P. gingivalis.
Previous research has shown people who look after their teeth and gums have lower risk of dementia - particularly women. Inflammation triggered by gum disease has also been implicated in heart disease and diabetes
Scientists at the University of Central Lancashire suspect that the microbe leads to the death of brain cells by triggering a chemical immune response.
Despite the findings, reported in the Journal of Alzheimer’s Disease, it ‘remains to be proven’ whether poor dental hygiene can lead to dementia in healthy people.
‘It is also likely that these bacteria could make the existing disease condition worse,’ said Professor StJohn Crean, of the university’s School of Medicine & Dentistry.
Dr Simon Ridley of the charity Alzheimer’s Research UK said oral bacterial infection could be a consequence of later stage Alzheimer’s, rather than a cause.
However, Dr Sim Singhrao, of the University of Central Lancashire, said: 'We are working on the theory when the brain is repeatedly exposed to bacteria or their debris from our gums, subsequent immune responses may lead to nerve cell death and possibly memory loss.
'Continued visits to dental hygiene professionals throughout one's life may be more important than currently envisaged with inferences for health outside of the mouth only.'
Dr Singhrao and her colleagues looked at tissue from 20 people - half of whom were suffering from dementia where the presence of products from Porphyromonas gingivalis were identified.
This bacterium is commonly associated with chronic gum disease and enters the bloodstream through daily activities such as eating, chewing and brushing teeth - but especially following invasive dental treatment.
From there it potentially gets into the brain on a regular basis and causes already primed brains cells to release more chemicals that kill neurons.
This could be one of the mechanisms that leads to changes in the brain which is typical of Alzheimer's and could be responsible for causing symptoms such as confusion and deteriorating memory.
Finding P. gingivalis in the brain of dementia sufferers, compared to those without, is significant as its presence has not been documented previously.
Brain samples from patients with the mental illness were infected with bugs that cause gum disease. The researchers believe when they reach the brain they trigger an immune response that destroys neurons
It also adds to a growing body of evidence that suggests an association between poor oral health and dementia.
Recent so far unpublished studies on animals by the same researchers has confirmed P. gingivalis in the mouth finds its way to the brain once gum disease becomes established.
Dean of dentistry Professor Stjohn Crean said: 'The bacteria could be a trigger that sets off a chain reaction in people pre-disposed to dementia.
'We are not saying this bacteria causes Alzheimer's, but it was present in the brains of the patients and not the control group.
'So people should pay particular attention to brushing their teeth and visiting the dentist to reduce the amount of bugs in their mouths - especially those with a history of dementia in their family.
'Whereas previous studies have indicated a link between dementia and other bacteria and viruses such as the Herpes simplex virus type I, this new research indicates a possible association between gum disease and individuals who may be susceptible to developing Alzheimer's disease if exposed to the appropriate trigger.
Dr Singhrao and colleagues looked at tissue from twenty people - half of whom were suffering from dementia where the presence of products from Porphyromonas gingivalis were identified
'It remains to be proven whether poor dental hygiene can lead to dementia in healthy people which obviously could have significant implications for the population as a whole. It's also likely these bacteria could make the existing disease condition worse."
Dr Singhrao said: "To help us prove our hypothesis we are hoping to use the Brains for Dementia Research tissue resource to examine brain tissue from people with both intact and compromised memory who have relevant dental records.
"The future of the research aims to discover if P. gingivalis can be used as a marker - via a simple blood test - to predict the development of Alzheimer's disease in at risk patients."
Previous research has shown people who look after their teeth and gums have lower risk of dementia - particularly women.
Inflammation triggered by gum disease has also been implicated in heart disease and diabetes.
A study of almost 5,500 elderly people found those who brushed their teeth less than once a day were up to 65 per cent more likely to develop dementia than those who brushed three times a day.
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