Study suggests association between poor dental health and Alzheimer’s

Researchers find bacteria linked to gum disease in brain in Alzheimer's.

Posted on 29th July 2013

A research team led by scientists at the University of Central Lancashire has reported an association between Alzheimer’s disease and the presence of periodontal disease bacteria in the brain. The findings were published in the Journal of Alzheimer’s Disease.

The team studied postmortem brain tissue from 10 people with Alzheimer’s and 10 people of the same age without the disease, looking for the presence of three major periodontal disease bacteria in the brain. These included Treponema denticola, Tannerella forsythia, and Porphyromonas gingivalis, all associated with poor oral hygiene and gum disease. The team observed signs of
the bacteria Porphyromonas gingivalis in four of the ten brains of those with Alzheimer’s compared to none of those without the disease. They were unable to observe either of the other two periodontal bacteria in the samples they examined.

The researchers propose that the P. gingivalis bacteria could enter the blood stream and reach the brain. While any possible contribution of these bacteria to the disease was not investigated in this study, the researchers suggest that the bacteria could act by triggering the immune system in the brain, which could have a detrimental effect in Alzheimer’s.

Dr Simon Ridley, Head of Research at Alzheimer’s Research UK, the UK’s leading dementia research charity, said:
“This is an early study with a very small number of samples that observed bacteria linked to gum disease in the brains of people with Alzheimer’s. We don’t know whether the presence of these bacteria in the brain contributes to the disease and further research will be needed to investigate this. It is possible that reduced oral hygiene and therefore P. gingivalis infection could be a consequence of later stage Alzheimer’s, rather than a cause.

“Other studies have suggested that infections, including oral infections, could be linked to Alzheimer’s and there is ongoing research in this area. It will be important for future studies to consider looking back at dental records, to correlate these kinds of observations with the level of oral hygiene during life.

“We know that there are likely to be many risk factors for Alzheimer’s and we need to investigate these in more detail to help develop new preventions or treatments. While a causal link between poor oral health and Alzheimer’s is still unclear, people who are worried about their dental health should still visit their dentist regularly.”

To learn more about research into risk factors for Alzheimer’s, explore our virtual dementia lab.

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