Abstract
The prevalence of anxiety, mood and trauma- and stress-related disorders are on the rise; however, efforts to develop new and effective treatment strategies have had limited success. To identify novel therapeutic targets, a comprehensive understanding of the disease etiology is needed, especially in the context of the holobiont, i.e., the superorganism consisting of a human and its microbiotas. Much emphasis has been placed on the role of the gut microbiota in the development, exacerbation, and persistence of psychiatric disorders; however, data for the oral microbiota are limited. The oral cavity houses the second most diverse microbial community in the body, with over 700 bacterial species that colonize the soft and hard tissues. Periodontal diseases encompass a group of infectious and inflammatory diseases that affect the periodontium. Among them, periodontitis is defined as a chronic, multi-bacterial infection that elicits low-grade systemic inflammation via the release of pro-inflammatory cytokines, as well as local invasion and long-distance translocation of periodontal pathogens. Periodontitis can also induce or exacerbate other chronic systemic inflammatory diseases such as atherosclerosis and diabetes and can lead to adverse pregnancy outcomes. Recently, periodontal pathogens have been implicated in the etiology and pathophysiology of neuropsychiatric disorders (such as depression and schizophrenia), especially as dysregulation of the immune system also plays an integral role in the etiology and pathophysiology of these disorders. This review will discuss the role of the oral microbiota associated with periodontal diseases in anxiety, mood and trauma- and stress-related disorders. Epidemiological data of periodontal diseases in individuals with these disorders will be presented, followed by a discussion of the microbiological and immunological links between the oral microbiota and the central nervous system. Pre-clinical and clinical findings on the oral microbiota related to periodontal diseases in anxiety, mood and trauma- and stress-related phenotypes will be reviewed, followed by a discussion on the bi-directionality of the oral-brain axis. Lastly, we will focus on the oral microbiota associated with periodontal diseases as a target for future therapeutic interventions to alleviate symptoms of these debilitating psychiatric disorders.
Highlights
Depression and anxiety disorders are among the most prevalent neuropsychiatric disorders (NPDs), with an estimated 322 million people living with depression and 264 million living with an anxiety disorder in 2015, according to the World Health Organization (WHO) global health estimates [1]
Of the top 12 pathways shared between distress and inflammation, all had opposite relationships with each factor [102], which is interesting given that, as noted above, several studies have reported a strong association between stress-related disorders and a pro-inflammatory state [61, 62, 65,66,67, 112, 113]
There is an epidemiological association between diseases with altered oral microbiota such as periodontitis and anxiety, mood and trauma- and stress-related disorders, as reported by systematic reviews and meta-analyses
Summary
Depression and anxiety disorders are among the most prevalent neuropsychiatric disorders (NPDs), with an estimated 322 million people living with depression and 264 million living with an anxiety disorder in 2015, according to the World Health Organization (WHO) global health estimates (https://apps.who. int/iris/bitstream/handle/10665/254610/WHO-MSD-MER2017.2-eng.pdf) [1]. Depressive disorders impose 1.84 disabilityadjusted life years (DALYs) while anxiety disorders impose 1.13 DALYs as recently described These neuropsychiatric disorders are chronic and debilitating and many patients do not respond to or adhere to the available treatment options. Adherence to psychiatric medications is further hindered by their side-effect profiles [5], and, due to the limited efficacy of antidepressants, nearly a third of patients do not respond to treatment [6]. The COVID-19 pandemic created an environment where several determinants of poor mental health are exacerbated resulting in a global increase of 27.6% in cases of major depressive disorder and a global increase of 25.6% in anxiety cases during the pandemic [7]. The significant burden of these disorders and the current limitations in their treatment highlight the need to identify all role players in their etiology to discover novel therapeutic targets to lighten disease burden
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
