A common oral bacterium best known for causing tooth decay may also be quietly damaging the brain and increasing the risk of Parkinson’s disease, according to new scientific research from South Korea.
The findings come from a collaborative study led by scientists at Pohang University of Science and Technology (POSTECH), Sungkyunkwan University School of Medicine and Seoul National University, shed light on how microbes in the mouth — once they reach the gut — may trigger inflammation and nerve damage associated with Parkinson’s.
Parkinson’s disease is one of the world’s most common neurodegenerative disorders, affecting up to 2 percent of people over 65. While earlier studies have suggested that gut bacteria play a role, scientists have long struggled to identify which microbes are involved — and how they influence the brain.
The study published in the journal Nature Communications identifies a familiar suspect: Streptococcus mutans, the bacterium responsible for dental caries (cavities). Researchers found that Parkinson’s patients had higher levels of this bacterium in their gut. More importantly, the microbe produces a compound called imidazole propionate (ImP) that can enter the bloodstream and travel to the brain.
Animal experiments showed what happened next. When mice were exposed to the bacterium — or to gut microbes engineered to produce the same chemicals — ImP levels rose in their blood and brain. Over time, the mice developed key features seen in Parkinson’s disease: loss of dopamine-producing brain cells; increased brain inflammation; movement difficulties; higher accumulation of alpha-synuclein protein.
Researchers were also able to block the damage by shutting down a specific brain-signalling pathway known as mTORC1, suggesting a potential new avenue for treatment.
“Our study provides a mechanistic understanding of how oral microbes in the gut can influence the brain,” said Professor Ara Koh of POSTECH, one of the study’s lead authors. “It highlights the potential of targeting the gut microbiota as a therapeutic strategy.”
The research team says the findings strengthen the idea that Parkinson’s may begin in the gut years before symptoms appear — and that preventive strategies might one day include strengthening oral and digestive health.
While further work is needed to confirm the role of this bacterium in humans, neurologists say the study adds to a growing body of evidence linking lifestyle, microbes and long-term brain health.
And for now, the takeaway may sound surprisingly simple: good oral hygiene could be good for your brain too.
