Single type of bacteria in the mouth linked to more severe MS symptoms

People living with multiple sclerosis (MS) who have higher levels of a particular type of mouth bacteria may be more likely to experience more severe symptoms, according to new research from Japan. The bacterium, Fusobacterium nucleatum, is known to play a role in periodontitis, a serious gum infection. This study adds to growing evidence that oral health and the immune system may be more closely linked to MS than previously understood.

Researchers are increasingly exploring how the bacteria that live in and on our bodies may influence MS. While much attention has focused on changes in the gut microbiome, this study highlights that bacteria in other areas of the body could also play an important part.

Periodontal disease is very common worldwide and has already been linked with several systemic health conditions. Previous studies have suggested that people with chronic periodontitis may have a higher risk of developing MS, although the reasons behind this remain unclear.

In this new study, tongue surface samples were collected from 98 people. This included 56 people living with MS, with an average age of 48.6. Researchers looked for four types of bacteria associated with periodontitis and compared levels across the group. Brushing habits and dental care routines were similar among all participants.

The findings showed that only Fusobacterium nucleatum was linked with more severe MS symptoms. People with higher levels of this bacterium were significantly more likely to have an Expanded Disability Status Scale score of four or above. This suggests a greater level of disability compared with those who had lower levels of the bacterium.

This association did not appear in people with other neurological conditions included in the study. Even when researchers accounted for other possible influences, the link between higher levels of F. nucleatum and increased disability remained strong.

People who had high levels of F. nucleatum alongside high levels of other periodontal bacteria had a much higher median disability score than those with lower levels. High levels of F. nucleatum alone increased the likelihood of more severe disability by around ten times.

The researchers concluded that the presence of this bacterium in the mouth may be associated with greater MS severity. The study does not show that the bacterium directly causes symptoms to worsen, but it highlights an important area for future research. Understanding more about the connection between oral health, bacteria and MS could help inform new approaches to managing long-term wellbeing.