Associations Between Oral Microbiota Pathogens and Elevated Depressive and Anxiety Symptoms in Men

Systemic inflammation is associated with depression. Certain oral bacterial species contribute to inflammation; however their potential association with mental disorders remains unclear. This study investigated the associations between oral microbiota pathogens and depressive and anxiety symptoms. Data came from 436 men from the Geelong Osteoporosis Study. Oral microbiota was characterized using 16S rRNA sequencing, and an oral pathogen composite was created comprising Porphyromonas gingivalis, Treponema denticola, Fusobacterium nucleatum, and Prevotella nigrescens species relative abundances. Binary variables were created representing elevated depressive and anxiety symptoms using the Hospital Anxiety and Depression Scale. Logistic regression was used to investigate associations between oral pathogens and elevated depressive/anxiety symptoms. Models were adjusted for confounders: age, socioeconomic status, diet, smoking, alcohol, exercise, obesity, and hypertension. We report a modest (nonsignificant) association between the pathogen composite and elevated depressive (OR 1.35 [95% CI 0.974, 1.87]) but not anxiety symptoms. Moreover, some of the comprising species were significantly associated with elevated depressive symptoms, including P. nigrescens (1.61 [1.21, 2.13]). Our exploratory analyses revealed that several other taxa were significantly associated with depression and anxiety symptoms. The findings suggest that specific oral bacteria may contribute to symptoms of depression, warranting further research through larger and longitudinal investigations.