The Oral-Brain Axis: Periodontal Bacteria Linked to Increased Multiple Sclerosis Severity
A groundbreaking medical discovery from Japan has revealed a concerning link between gum health and chronic neurological disease. The study suggests that the presence of a specific oral bacterium, Fusobacterium nucleatum, is closely associated with the severity of disability in patients with Multiple Sclerosis (MS). This research highlights a unique "oral-brain axis," where chronic inflammation in the mouth may trigger immune responses that accelerate damage to the central nervous system.
The findings emphasize that for patients with neurological disorders, maintaining oral hygiene is no longer just an aesthetic routine; it is a critical factor in managing the progression of their disease.
The Data: Key Indicators from the Study
Led by a team at Hiroshima University, the study analyzed tongue coating samples from patients with various demyelinating diseases. The data points to a strong correlation:
Higher Disability Risk: MS patients with high levels of Fusobacterium nucleatum were 10 times more likely to experience severe disability.
Significant EDSS Scores: The abundance of this bacterium correlated with higher Expanded Disability Status Scale (EDSS) scores—specifically a score of 4 or more, indicating significant mobility limitations.
Disease Specificity: This link was uniquely found in MS patients and was absent in similar conditions like neuromyelitis optica (NMOSD) or MOGAD.
Severity Statistics: Approximately 61.5% of patients with high bacterial levels fell into the moderate-to-severe disability category, compared to only 18.6% in the low-level group.
The Underlying Mechanism: How Bacteria Influence the Nervous System
Researchers explain that this bacterium acts as a catalyst for systemic inflammation through several pathways:
The "Bridge" Bacterium: Fusobacterium nucleatum is known as a "bridge bacterium." It helps various microbial communities attach to one another, forming stronger, more destructive dental plaque (biofilm).
Triggering Neuroinflammation: Gum infections release inflammatory molecules into the bloodstream. These molecules can potentially disrupt the blood-brain barrier or influence cranial nerves, worsening inflammation within the brain.
Immune System Interference: The presence of this bacterium is thought to activate immune cells that mistakenly attack the myelin sheath—the protective coating of nerves—speeding up the loss of nerve function in MS patients.
Clinical and Patient Implications
The results of this study offer a new direction for integrative care for neurological patients:
Mandatory Dental Screenings: Neurologists are encouraged to include routine dental check-ups as a standard part of the long-term management protocol for MS patients.
Microbiome Management: Controlling harmful bacterial populations through professional periodontal treatment may help minimize the inflammatory triggers that worsen a patient's physical condition.
Patient Awareness: Individuals with MS need to be aware that untreated gum infections have a direct impact on their future risk of physical disability.
Potential New Therapies: These findings open doors for research into targeted therapies, such as specific antiseptics or probiotics designed to suppress F. nucleatum in at-risk patients.
Original Article Details
Original Title: Study links periodontal bacterium to multiple sclerosis disability severity
Source: Oral Health Group / Hiroshima University
Publication Date: December 2025