Of course, gum disease isn’t the only oral condition that can affect the health of your brain. Any infection in the mouth has the potential to spread and do damage – even caries, better known as tooth decay.

From the Mouth to the Heart to the Brain

A couple summers ago, a 49-year old Chicago architect named Jay Keller suddenly began to experience profound fatigue. He ignored it, thinking it was just a cold, but his symptoms continued to worsen. A trip to urgent care provided no help.

Then came an excruciating and persistent headache. With his annual physical coming up, he decided to just tough things out and talk with his doctor then. Bloodwork done at that visit showed that he had endocarditis – an infected heart valve.

The infection had been caused by S. mutans, the main type of bacteria that causes tooth decay.

But that diagnosis wasn’t the end of Keller’s story.

The heart is the central pump of the body, so if part of that pump is infected, blood is flowing past an infected piece of machinery, said Dr. Babak Jahromi, Keller’s neurosurgeon at Northwestern Medicine.

“What that means is pieces of infected junk will just fly off and lodge anywhere,” he noted. “That had happened in Jay… one of these had lodged in his brain, infected the brain arteries.”

The result was a mycotic brain aneurysm. This is an abnormal bulging of a brain artery caused by infection. It can rupture and bleed into the brain. It can cause a stroke. It can damage the brain. It can send you into a coma. It can even kill you.

Fortunately, surgery saved Keller’s life – one operation for the aneurysm, another for a pre-existing heart valve issue that had put him at greater risk for the kind of infection he experienced – infection triggered by microbes from his mouth.

Oral Bacteria Found in Brain Abscesses

When oral bacteria enter the bloodstream – often through small abrasions in the gums – they can be carried to many parts of the body. The brain is one of the most critical sites, for once oral bacteria reach the brain, they assault neurons, which can lead to memory loss and other complications. In severe cases, an abscess can form.

A 2022 study in the Journal of Dentistry noted one particular type of caries-causing bacteria that may raise the risk of a brain abscess: a relative of S. mutans known as S. anginosus, which is commonly found in dental abscesses.

Researchers analyzed records and microbiological data from just under 90 patients who had been admitted to a hospital with brain abscesses. They then looked for the presence of oral bacteria, whether the cause of the abscess had been identified or not.

Over half of the cases had no known cause. These patients were roughly three times as likely to have oral bacteria in their samples. They also had significantly higher counts of S. anginosus.

S. mutans & the Brain

Much of the research on the potential relationship between tooth decay and brain health, though, has focused on S. mutans. Studies have shown, for instance, that it may raise the risk of microbleeds in the brain and cognitive impairment more generally. It may raise the risk of hemorrhagic stroke.

A large 2021 study investigated stroke risk in particular. Researchers collected data from over 6500 individuals who had no history of stroke and followed them for three decades. Through the first 15 years, those who developed caries had a slightly higher risk of stroke. Then, suddenly, their risk skyrocketed.

Over the next 15 years, those who had developed caries had a risk of stroke from brain bleed that was 4.5 times higher than those with healthier mouths – even after adjusting for age, gender, race, and high blood pressure. S. mutans seemed the most likely culprit.

This is especially serious when you consider that while brain bleeds (the clinical term is “intracerebral hemorrhages”) make up only a small portion of all strokes, they’re more deadly than the more common ischemic strokes, which are caused by artery blockages.

Healthy Mouth, Healthy Body

While conditions like these are relatively rare, they serve as an important reminder that oral health plays a role in your overall health and well-being. A healthy mouth supports a healthy body, and an unhealthy mouth raises your risk of many other conditions (not just those involving the brain).

In this respect, it’s also great motivation for visiting us regularly for cleanings and exams (at least twice a year; more frequently if you have active gum disease), and to maintain a good oral hygiene routine at home. Brushing twice and flossing once each day is just the start. It also involves eating healthy, staying physically active, getting enough good quality sleep each night, managing stress, avoiding tobacco, and being moderate if and when you choose to drink alcohol.

All of these things have a demonstrated effect on oral health, just as they do on whole body health. The two ARE connected, after all.