Published: Sun, January 27, 2019
Medicine | By Tracy Klein

Alzheimer's linked to infection of the brain by gum disease bacterium

Alzheimer's linked to infection of the brain by gum disease bacterium

New Scientist said a number of teams had been investigating Porphyromonas gingivalis, the bacteria behind chronic gum disease, and found that it attacks and inflames brain regions affected by Alzheimer's.

Researchers from the institute conducted the study in collaboration with neurologists from the Washington University School of Medicine in St. Louis and the Huntington Medical Research Institutes in Pasadena.

Dr. David Reynolds, a chief scientific officer at the charity Alzheimer's Research UK who did not work on the paper, commented: "The presence of a single type of bacteria is extremely unlikely to be the only cause of the condition".

"Infectious agents have been implicated in the development and progression of Alzheimer's disease before, but the evidence of causation hasn't been convincing", stated Stephen Dominy, lead author of the study.

'The upcoming clinical trial will be a crucial test to see if this can be a potential treatment for Alzheimer's'.

It's possible that news of the possible link will lead to people spending more time on their dental health than they now do, though: One study found less than one third of Americans floss daily.

Although it is still unknown if getting more sleep protects one against Alzheimer's, Holtzman agreed that it might help to slow down the process if it has already begun. "They did a lot of different experiments to build the case that gingipains are a drug target in Alzheimer's disease", he says. Each research organization was responsible for bringing in the trial's clinical patients and collecting the resources and data the USC team used to inform its findings. In both mice and human brain tissue, scientists discovered a drop in receptors for glutamate, a neurotransmitter in the brain necessary for both learning and short-term memory retention.

Mice are nocturnal animals, tau levels in fluids surrounding brain cells were found to be twice as high at night when they were more awake and active than during the day when they dozed more frequently; disturbing rest during the day caused daytime tau levels to double.

In the study, "Neuropsychological Deficit Profiles, Vascular Risk Factors, and Neuropathological Findings in Hispanic Older Adults with Autopsy-Confirmed Alzheimer's Disease" in the Journal of Alzheimer's Disease, autopsies of 14 Hispanic and 20 non-Hispanic persons were reviewed, all with autopsy-confirmed physiological evidence of AD.

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There was also caution about the fact the drug tests had been in mice.

The new study found that toxic enzymes from the bacteria Pg, called gingipains, were also found in the brains of Alzheimer's disease patients and that their levels correlated with levels of tau.

A drug developed by the company, COR38, is now in human trials.

Firstly, researchers looked at post-mortem brain tissue samples from around 100 people with and without Alzheimer's disease. "We would send patients off for more specific Alzheimer's tests if the results come back showing a cause for concern", Professor Masters said.

"An even more notable aspect of this study is demonstration of the potential for a class of molecule therapies targeting major virulence factors to change the trajectory of AD, which seems to be epidemiologically and clinically associated with periodontitis", Potempa said. In the United Kingdom, 850,000 people live with dementia, according to the Alzheimer's Society.

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