09 February 2023

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Scientists find link between oral microbiome, depression and anxiety

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There is growing evidence to suggest that changes in the gut microbiota play an important role in the development of anxiety, depression and other psychiatric disorders. However, little has been studied about how the oral microbiome affects mental health. To change this, researchers from Xi'an Jiaotong University conducted a case-control study on the subject and found a link between specific oral bacteria and the development of depression and anxiety.

According to the World Health Organization, anxiety disorders and depression are prevalent mental illnesses, with around 264 million suffering from anxiety and 322 million being affected by depression worldwide. The high prevalence of these mental illnesses and negative consequences have made them worrisome, the study authors said.

The research team sought to assess the relationship between salivary and dorsum tongue microbiomes and anxiety and depression. To this end, they analyzed the individual genetic predisposition of a large cohort of UK Biobank participants with depression and anxiety against controls regarding salivary and back of the tongue microbiomes. Researchers used the most recent summary data from an oral microbiome genome-wide association study.

The team identified significant interactions between salivary and dorsum tongue microbiomes and anxiety and depression. They found oral bacteria such as Centipeda periodontii, Granulicatella and Eggerthia associated with both mental illnesses.

There may be several mechanisms for the link between poor oral health and mental disorders. It is known that periodontal disease affects the gums and periodontium and that bacteria can enter the bloodstream through damage to the gums. If the blood-brain barrier is weakened, bacteria can also enter the brain. Through messenger substances that promote inflammation, periodontal disease can also indirectly influence the central nervous system.

The exact mechanisms by which these conditions develop and possible forms of prevention, for example, dental care or periodontal prophylaxis, oral hygiene and nutritional strategies, now need to be further investigated.

"This work highlights the need for more research on the potential role of the oral microbiome in mental health disorders to improve our understanding of disease pathogenesis, which could lead to new diagnostic targets and early intervention strategies," the study authors concluded.

This article originally appeared in Odontologia33. 

Chun'e Li et al. "A genetic association study reveals the relationship between the oral microbiome and anxiety and depression symptoms." Front. Psychiatry, 10 November 2022 Sec. Behavioral and Psychiatric Genetics. Volume 13 - 2022. https://doi.org/10.3389/fpsyt.2022.960756