Bacteria behind gum disease linked to Alzheimer’s

Female scientist in a lab looks into a petri dish she is holding in front of her face. Her black hair is down. She wears a white lab coat, plastic goggles, and purple gloves.

By Alice Tuohy | Wednesday 23 January 2019

Scientific Advances: Porphyomonas gingivalis in Alzheimer’s disease brains: evidence for disease causation and treatment with small-molecule inhibitors

Researchers have found Porphyomonas gingivalis, a bacteria linked to gum disease, present in the brains of people with Alzheimer’s disease. The international team of researchers also found that treating mice who have an oral P. gingivalis infection with a drug targeting the toxic substances released by the bacteria could prevent the build-up of the hallmark Alzheimer’s protein, amyloid. The results are published today (Wednesday 24 January) in the scientific journal Science Advances.

Dr David Reynolds, Chief Scientific Officer from Alzheimer’s Research UK, said:
“Previously the P. gingivalis bacteria associated with gum disease has been found in the brains of people with Alzheimer’s but it remains unclear what role, if any, it plays in the development of the disease. In this well-conducted study, researchers were able to show that when mice were given P. gingivalis, the bacteria was found in the brain alongside higher levels of the hallmark Alzheimer’s protein, amyloid.

“While some studies have found higher levels of bacteria in the brain during Alzheimer’s, it has been difficult to tell if they have played a direct role in the development of the disease.

“We know diseases like Alzheimer’s are complex and have several different causes, but strong genetic evidence indicates that factors other than bacterial infections are central to the development of Alzheimer’s, so these new findings need to be taken in the context of this existing research.

“Maintaining good dental health is an important part of a healthy lifestyle, and while we don’t yet fully know the extent to which it can affect our dementia risk, the presence of a single type of bacteria is extremely unlikely to be the only cause of the condition.

“Drugs targeting the bacteria’s toxic proteins have so far only shown benefit in mice, yet with no new dementia treatments in over 15 years it’s important that we test as many approaches as possible to tackle diseases like Alzheimer’s. It’s important we carefully assess all new potential treatments, and this drug is currently in an early phase clinical trial to establish if it is safe for people. We will have to see the outcome of this ongoing trial before we know more about its potential as a treatment for Alzheimer’s.”


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Alice Tuohy