Dental News - Study links oral microbiome to depression and anxiety

Franziska Beier, Dental Tribune International

Tue. 17. January 2023

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XI’AN, China: An increasing body of evidence has suggested that changes in the gut microbiota play a significant role in the development of anxiety, depression and other psychiatric disorders. However, how the oral microbiome affects mental health has been little studied. To change this, researchers from Xi’an Jiaotong University have conducted a case–control study on the topic 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, around 264 million suffering from the former and 322 million from the latter globally. The high prevalence of these mental illnesses and their negative consequences have made them highly concerning, stated the study authors.

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

The team identified significant interactions between salivary and tongue dorsum microbiomes and anxiety and depression. They found oral bacteria such as Centipeda periodontii, Granulicatella and Eggerthia to be 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 gingivae and periodontium and that bacteria can enter the bloodstream via damage to the gingivae and, if the blood–brain barrier is weakened, can also enter the brain. By means of inflammation-promoting messenger substances, periodontal disease can also indirectly influence the central nervous system.

The exact mechanisms by which these conditions develop and possible ways of prevention, for example dental care (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, potentially leading to new diagnostic targets and early intervention strategies,” concluded the study authors.

The study, titled “A genetic association study reveals the relationship between the oral microbiome and anxiety and depression symptoms”, was published online on 10 November 2022 in Frontiers in Psychiatry.