New Delhi, Dec 30 : Abundance of severe gum disease -- periodontitis -- may worsen disability for people with multiple sclerosis (MS), a chronic autoimmune disease of the central nervous system.

Previous studies have shown that periodontitis may contribute to central nervous system disorders through chronic inflammation. However, its role in multiple sclerosis has been unclear.

The new research, published in the journal Scientific Reports, found that high levels of Fusobacterium nucleatum -- a bacterium found in the mouth -- were associated with about ten-fold higher odds of severe disability in multiple sclerosis patients.

"While the gut microbiome has been extensively investigated in multiple sclerosis, the potential involvement of the oral microbiome has remained largely unexplored. Because the oral cavity is a major source of chronic inflammation and represents a potentially modifiable factor, clarifying its relationship with multiple sclerosis severity is important for understanding disease mechanisms and developing new preventive strategies," said Masahiro Nakamori, an associate professor and lecturer at Hiroshima University Hospital.

The team noted that nearly two-thirds (61.5 per cent) of multiple sclerosis patients with a high relative abundance of Fusobacterium nucleatum fell into the moderate-to-severe disability range, compared with roughly one-fifth (18.6 per cent) of those with milder disease.

No such association was observed in patients with neuromyelitis optica spectrum disorder or myelin oligodendrocyte glycoprotein antibody-associated disease. MS patients with both Fusobacterium nucleatum and at least one other periodontal pathogen showed even higher disability.

"Fusobacterium nucleatum may act as a hidden 'bridge bacterium' -- not only bridging bacterial communities in dental biofilms, but also potentially linking oral inflammation to neurological disability," said Nakamori.

MS is a central inflammatory demyelinating disease that targets the myelin sheath, the protective layer that wraps around some nerve cells.

While the specific cause of multiple sclerosis remains unknown, viral infections, smoking, vitamin deficiencies, and genetic predispositions are thought to be possible contributing factors.

The team now hopes to conduct larger, multi-center studies to validate the association between oral bacteria and multiple sclerosis severity.

/IANS