Study links gum disease-causing bacteria to Alzheimer's disease

By Ashley Welch

/ CBS News

Researchers say they've found more evidence linking bacteria found in a common type of gum disease to dementia. A new study, published in the journal Science Advances, found a key pathogen associated with chronic periodontal disease in the brains of people with Alzheimer's disease.

The study authors say these results, plus additional testing in mice, provide "solid evidence" of a link between the two diseases and may offer a potential new way to treat Alzheimer's. The devastating illness affects 47 million people worldwide, and there is no cure.

However, Alzheimer's experts not involved in the research caution that it is too early to tell how strong this association is, or whether it could lead to effective treatments.

What the new study found

Scientists from Cortexyme, Inc., a privately held, clinical-stage pharmaceutical company, analyzed the brain tissues of patients with Alzheimer's disease and found evidence of Porphyromonas gingivalis, the bacteria associated with gum disease.

Further tests in mice found that this bacteria could travel from the mouth to the brain and increased production of amyloid beta, a protein strongly associated with Alzheimer's.

In addition to the Porphyromonas gingivalis, the researchers found toxic enzymes produced by the bacteria called gingipains in the neurons of patients with Alzheimer's. Higher levels gingipain were associated with tau and ubiquitin, two other proteins involved in the development of Alzheimer's.

The team also tested drugs in mice aimed at clearing the harmful bacteria and blocking its toxic enzymes. In these lab experiments, scientists were able to reduce the number of Porphyromonas gingivalis bacteria in the infected brains, block the production of toxic proteins, and halt degeneration in the brain.

The researchers hope this will provide the basis for developing a new therapy that could one day treat humans in a similar way.

"The findings of this study offer evidence that P. gingivalis and gingipains in the brain play a central role in the pathogenesis [development] of AD [Alzheimer's disease], providing a new conceptual framework for disease treatment," the study authors write.

Research on infections and Alzheimer's disease

This is not the first study to show a relationship between gum disease and Alzheimer's.

A 2017 study out of Taiwan found that people with chronic gum disease lasting 10 years had a 70 percent increased risk for developing Alzheimer's. Another small study published in 2016 in the journal PLOS ONE found gum disease was associated with a six-fold increase in the rate of cognitive decline in people with mild to moderate dementia.

Other research has looked at whether various bacterial, viral, or fungal infections may play a role in Alzheimer's, but there is currently not enough evidence to say.

"The idea that bacteria and viruses may play a part in brain disease like Alzheimer's is not necessarily new," Rebecca Edelmayer, Ph.D., director of scientific engagement for the Alzheimer's Association, told CBS News. "But what this paper suggests is really an association and not causation and that should be very clearly emphasized when we're talking about studies like this. More research is needed to really identify a causative role for microbes."

In other words, it's unknown whether gum disease increases the risk of Alzheimer's or if people with dementia have an increased risk of gum disease because of poor oral care.

Edelmayer also cautions not to put too much weight on drugs tested in mice. "It really will be important to see how this plays out in human randomized controlled trials, which is the gold standard for understanding whether a therapeutic targeting something like the P. gingivalis mechanism would actually be effective," she said.

Could good oral care help prevent Alzheimer's?

While taking care of your teeth and gums is an important part of healthy aging, Edelmayer says it's too early to say if those steps could help prevent Alzheimer's disease.

Of course, there are many factors that go into someone's individual risk of developing dementia. The Alzheimer's Association has a campaign called "10 Ways to Love Your Brain" to help people lower their risk.

"We think a lot about things like diet, exercise, a good management of cardiovascular health, getting good sleep. All of these things could potentially play a role as a lifestyle intervention for decreasing your risk of developing cognitive decline," Edelmayer said.

Alzheimer's expert shares healthy brain advice

She notes that good oral health could one day fall into one of these categories if there's more evidence to show that gum disease actually increases the risk for developing dementia.

Still, Edelmayer says with so much still unknown about the disease, studies like this are important for gaining a better understanding of Alzheimer's.

"I think the research really reinforces the complexity of Alzheimer's disease," she said. "It highlights the importance of sharing information and experiments and data like this very freely and widely across the research community so this robust discussion about this kind of science takes place."

First published on January 24, 2019

© 2019 CBS Interactive Inc. All Rights Reserved.

Ashley Welch

Ashley Welch covers health and wellness for CBSNews.com

Twitter

Study links gum disease bacteria to Alzheimer's

Scientists found the key pathogen of gum disease in the brains of people with Alzheimer's, but other experts caution more research is needed to understand the connection

updated 5M ago

Florida's secretary of state Mike Ertel resigns after blackface photos surface

The longtime Republican official was forced to resign just 17 days into his new post

updated 2M ago

New Horizons beams back best image yet of Ultima Thule

NASA's New Horizons probe has sent back more photos from the far side of the solar system, a billion miles past Pluto

updated 23M ago

More federal workers seeking new jobs during shutdown

Website's data show a spike in job searches from workers at agencies that have gone unfunded—and it's spreading

updated 35M ago

Americans optimistic about economy – CBS News poll

But they're unhappy about the direction of the country, according to a new CBS News poll

updated 37M ago

Florida's secretary of state Mike Ertel resigns after blackface photos surface

The longtime Republican official was forced to resign just 17 days into his new post

updated 2M ago

More federal workers seeking new jobs during shutdown

Website's data show a spike in job searches from workers at agencies that have gone unfunded—and it's spreading

updated 35M ago

Americans optimistic about economy – CBS News poll

But they're unhappy about the direction of the country, according to a new CBS News poll

updated 37M ago

Elizabeth Warren plans to propose a "wealth tax"

Sen. Elizabeth Warren plans to propose a "wealth tax" on Americans with more than $50 million in an effort to combat inequality

updated 21M ago

How you can help federal workers during shutdown

Nearly 800,000 government workers will miss their second paychecks Friday due to record-long government shutdown

2H ago

Pompeo pledges $20 million in aid to Venezuela

America's top diplomat called on other nations to shun the "now-defunct" Maduro regime and recognize the Venezuelan opposition

4H ago

"New abnormal": Doomsday Clock still at 2 minutes to midnight

"Though unchanged from 2018​, this setting should be taken not as a sign of stability"

5H ago

Soccer star's audio message from missing plane: "I'm so scared"

Emiliano Sala and his pilot disappeared Monday on the short flight between France and Britain, over the frigid waters of the English Channel

7H ago

Many not sleeping enough – or well enough – and that's a killer

An estimated one-third of Americans suffer chronic "sleep deficit," but it's become such a problem in Japan that some companies are taking action

8H ago

U.S. backing of Venezuelan opposition comes with risks

President Nicolas Maduro shunned by White House and U.S. allies, but some major world powers still have his back

9H ago

Kate Hudson on her "genderless" approach to raising kids

Hudson and Danny Fujikawa's daughter, Rani, is named after Fujikawa's father, Ron

3H ago

Meek Mill, Jay-Z and others launch initiative for criminal justice reform

According to the Reform Alliance, 4.5 million people are currently on parole or probation for unreasonable terms

4H ago

Dad and son dance to "Frozen" in viral video

When his son wanted to dance to "Frozen" songs, this dad put on an Elsa costume – because it's important to just "let it go" and be yourself

7H ago

"The Wizard of Oz" returning to theaters for 80th anniversary

You can see the beloved 1939 film in theaters starting this weekend

15H ago

Carrie Underwood welcomes baby No. 2

The country singer and her former hockey player husband welcomed baby number two on Monday

Jan 23

New Horizons beams back best image yet of Ultima Thule

NASA's New Horizons probe has sent back more photos from the far side of the solar system, a billion miles past Pluto

updated 23M ago

15 senators demand FCC, FTC investigate carriers selling location data

The demand comes after a report found carriers such as AT&T were selling data to buyers such as bounty hunters

updated 25M ago

Scammers impersonating YouTube stars

Video platform says it's working to shut down a scheme targeting fans of popular content creators

1H ago

"New abnormal": Doomsday Clock still at 2 minutes to midnight

"Though unchanged from 2018​, this setting should be taken not as a sign of stability"

5H ago

Under Armour is developing spacesuits for Virgin Galactic

This comes as the race to make commercial space travel a reality is intensifying

8H ago

Study links gum disease bacteria to Alzheimer's

Scientists found the key pathogen of gum disease in the brains of people with Alzheimer's, but other experts caution more research is needed to understand the connection

updated 5M ago

Gold Medal flour recalled over salmonella fears

General Mills says only 5-pound bags with use-by dates of April 20 are affected and no related confirmed illnesses have been reported

3H ago

Many not sleeping enough – or well enough – and that's a killer

An estimated one-third of Americans suffer chronic "sleep deficit," but it's become such a problem in Japan that some companies are taking action

8H ago

Family behind OxyContin maker fueled opioid crisis, Massachusetts AG says

In a lawsuit, the state targets eight members of the Sackler family, alleging they are "personally responsible" for deceptively selling OxyContin

4H ago

Formerly conjoined twins thriving after rare, complex surgery

The girls are among the youngest twins joined at the head​ to be successfully separated

23H ago

More federal workers seeking new jobs during shutdown

Website's data show a spike in job searches from workers at agencies that have gone unfunded—and it's spreading

updated 35M ago

Americans optimistic about economy – CBS News poll

But they're unhappy about the direction of the country, according to a new CBS News poll

updated 37M ago

15 senators demand FCC, FTC investigate carriers selling location data

The demand comes after a report found carriers such as AT&T were selling data to buyers such as bounty hunters

updated 25M ago

Scammers impersonating YouTube stars

Video platform says it's working to shut down a scheme targeting fans of popular content creators

1H ago

Elizabeth Warren plans to propose a "wealth tax"

Sen. Elizabeth Warren plans to propose a "wealth tax" on Americans with more than $50 million in an effort to combat inequality

updated 21M ago

Rape suspect "fooled everybody," says mom of another patient

"He was very loving, very compassionate. Or he pretended to be. And I really trusted him"

6H ago

Man took bank "by force" before killing 5 women, police say

Authorities say Zephen Xaver opened fire inside SunTrust branch in Sebring, Florida

updated 1M ago

Ex-girlfriend gives new details about accused bank shooter

Zephen Xaver has long been fascinated with the idea of killing, former girlfriend tells CBS affiliate

8H ago

Jennie-O to donate $25,000 reward money to Jayme Closs

The FBI and Jennie-O contributed a total of $50,000 for information on Closs' whereabouts; she had been kidnapped for nearly three months

15H ago

5 people killed in Florida bank shooting; suspect in custody

Zephen Xaver, 21, has been taken into custody Wednesday after SWAT team entered SunTrust Bank branch in Sebring, Florida

13H ago