A growing body of evidence suggests that changes in the gut microbiota play a significant role in the development of anxiety, depression and other psychiatric disorders. However, little is known about how the oral microbiome affects mental health. To remedy this, researchers at Xi'an Jiaotong University conducted a case-control study on the topic and found an association between specific oral bacteria and the development of depression and anxiety.
According to the World Health Organization, about 264 million people in the world suffer from anxiety disorders and 322 million from depression. The high prevalence of these mental illnesses and their negative consequences have made them quite worrisome, the study authors said.
The researchers aimed to evaluate the relationship between salivary gland and tongue microbiomes and psychiatric disorders. To this end, they analyzed the individual genetic predisposition of a large cohort of British Biobank participants with depression and anxiety compared to controls for their salivary gland and dorsum of tongue microbiome using the most recent pooled data from the genome-wide oral microbiome association study.
The team identified significant interactions between the microbiomes of the salivary glands and the back of the tongue and anxiety and depression. They found that oral bacteria such as Centipeda periodontii, Granulicatella and Eggerthia are associated with both mental illnesses.
There may be several mechanisms of association between poor oral health and psychiatric disorders. It is known that periodontitis affects the gums and periodontium and that bacteria can enter the bloodstream through gum injury and, if the blood-brain barrier is weakened, can also enter the brain. Through “messenger substances” that promote inflammation, periodontal disease can also indirectly affect the central nervous system.
The exact mechanisms by which these conditions develop, and possible ways of prevention, such as dental care (periodontal prevention), oral hygiene, and nutritional strategies, now need to be further explored.
“This work highlights the need for more research into the potential role of the oral microbiome in psychiatric disorders to improve our understanding of disease pathogenesis, potentially leading to new diagnostic targets and early intervention strategies,” the study authors concluded.