Alzheimer’s could be caused by bad oral hygiene, according to new research — further evidence that bacteria plays a role in developing the disease
By Lindsay Dodgson
Contrary to what a lot of people think, dementia is not an inevitable part of getting older. It is caused by diseases like Alzheimer’s and is the fifth biggest cause of death worldwide.
Alzheimer’s is preventable in some cases, but the problem is the direct causes of it aren’t fully understood.
However, new research, published in the journal Science Advances, suggests Porphyromonas gingivalis, a bacteria that chronic gum disease, may play a role.
Researchers found that people with Alzheimer’s disease had higher concentrations of proteins produced by P. gingivalis in their brains. Also, in experiments on mice, those infected with P. gingivalis showed symptoms of early-stage dementia, and had more inflammation, neural damage, and amyloid plaques in their brains.
The new research, from pharmaceutical firm Cortexyme, also found that two toxic proteins P. gingivalis uses to damage human tissue were found in 91% and 96% of the brains with Alzheimer’s sampled, compared to 39% and 52% of brains without. The concentration of the proteins was “significantly higher” in brain samples from people with Alzheimer’s disease.
Sim Singhrao, from the University of Central Lancashire, told New Scientist this is the first time research has shown how these enzymes can kill neurons and cause dementia.
The company has now developed a drug that could clear this bacterial infection and stop brain deterioration. It’s currently being tested in clinical trials.
“This provides hope of treating or preventing Alzheimer’s disease one day,” Singhrao added.
This research is exciting, and it adds to what researchers already know about the potential role of bacteria in developing Alzheimer’s. But it is in very early stages. According to Alzheimer’s UK, there is “not enough evidence to know whether treating infections would be a good strategy to treat Alzheimer’s or to reduce the risk of the condition.”
Last June, a controversial theory about what causes Alzheimer’s diseasewas reignited. Researchers from from the Icahn School of Medicine at Mount Sinai found that 622 brains from people who had signs of Alzheimer’s had twice the level of herpes virus present than the 322 from people who did not.
As well as herpes, pneumonia and other bacteria have also been linked to Alzheimer’s disease through the DNA sequencing of brain tissue.
However, as Alzheimer’s UK points out, it is not yet clear whether bacterial or viral infections could trigger Alzheimer’s, or the other way around.
New Scientist reported that a team in Melbourne are developing a vaccine for P. gingivalis.
“A vaccine for gum disease would be welcome — but if it also stops Alzheimer’s the impact could be enormous,” the article says.
Overall, Alzheimer’s is likely to be caused by a number of factors, including genetics and lifestyle. For instance, another new study from Washington University School of Medicine in St. Louis found how not getting enough sleep could be linked to having more toxic clumps of tau in the brain — a vital protein that maintains the shape of brain cells, but tangles in and around nerve cells if there’s too much of it.
“The interesting thing about this study is that it suggests that real-life factors such as sleep might affect how fast the disease spreads through the brain,” said David Holtzman, the leaf author of the study.
“We’ve known that sleep problems and Alzheimer’s are associated in part via a different Alzheimer’s protein — amyloid beta — but this study shows that sleep disruption causes the damaging protein tau to increase rapidly and to spread over time.”
There’s no definite answer to what causes Alzheimer’s and dementia, but it’s clear that the more pieces of the puzzle we have, the better.