Parkinson’s disease can be caused by Streptococcus mutans, a bacterium commonly associated with dental cavities (Image: Pexels)
People often believe that tooth decay is a local problem, painful, inconvenient, but confined to the mouth. New research from South Korea suggests it may not be that simple. A bacterium best known for causing cavities could be quietly influencing the brain, raising fresh questions about how oral health, gut health and neurological disease are deeply connected.
The study, led by researchers at Pohang University of Science & Technology (POSTECH), focused on Parkinson’s disease, a neurological condition that affects movement, balance and muscle control. Parkinson’s impacts around 1–2 percent of people over 65 and has long puzzled scientists searching for its origins.
Earlier studies had hinted that people with Parkinson’s disease often have different gut bacteria compared to healthy individuals. What remained unclear was which microbes mattered, and how they could influence the brain. The POSTECH team found a compelling suspect: Streptococcus mutans, a bacterium commonly associated with dental cavities.
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Researchers discovered unusually high levels of S. mutans in the gut microbiomes of people with Parkinson’s. Once settled in the gut, this bacterium produces an enzyme called urocanate reductase and a compound known as imidazole propionate (ImP). The team found it circulating in the bloodstream and, crucially, reaching the brain. There, it appeared to damage dopamine-producing neurons, the very cells that are lost in Parkinson’s disease.
To test the theory, scientists turned to mouse models. Some mice were given S. mutans directly in their gut, while others received genetically modified bacteria designed to produce the same harmful enzyme. In both cases, ImP levels rose in the blood and brain. As a consequence, the mice developed inflammation in the brain, motor difficulties, and damage to dopaminergic neurons. They also showed increased accumulation of alpha-synuclein, a protein strongly linked to Parkinson’s progression. In essence, the animals began to display Parkinson’s-like features.
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Further experiments revealed that these effects depended on a cellular signalling system called mTORC1. When researchers blocked this pathway using a drug, the damage slowed significantly. Brain inflammationdecreased, neuron loss was reduced, and the mice’s movement improved. This finding suggests that it may be possible to interrupt the harmful chain reaction—from oral bacteria to gut metabolites to brain damage.
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“Our study provides a mechanistic understanding of how oral microbes in the gut can influence the brain,” said Professor Ara Koh, one of the study’s lead researchers.
FAQs on Parkinson’s Disease
1. What is Parkinson’s disease?
Parkinson’s disease is a neurological condition that affects movement, balance, and muscle control, impacting around 1–2 percent of people over 65.
2. How is Parkinson’s disease related to gut bacteria?
Research indicates that gut bacteria, particularly Streptococcus mutans, may play a role in Parkinson’s by producing compounds that damage dopamine-producing neurons in the brain.
3. What did the POSTECH researchers discover about Parkinson’s disease?
The POSTECH team found high levels of Streptococcus mutans in the guts of Parkinson’s patients, linking it to brain damage and neuron loss through the production of harmful compounds.
4. How did the researchers test their theory on Parkinson’s disease?
Scientists used mouse models, introducing Streptococcus mutans in their guts, which led to inflammation, motor difficulties, and neuron damage, mimicking Parkinson’s disease features.
5. Can the harmful effects of Streptococcus mutans be blocked?
The study revealed that blocking the mTORC1 signalling pathway significantly reduced brain inflammation and neuron loss, suggesting a potential way to interrupt the harmful chain reaction caused by this bacterium.
Disclaimer: This article, including health and fitness advice, only provides generic information. Don’t treat it as a substitute for qualified medical opinion. Always consult a specialist for specific health diagnosis.