Association between periodontal diseases and bipolar disorder: implications for therapeutic interventions: A narrative review

Abstract

Chronic low-grade inflammation plays a role in the pathophysiology of bipolar disorder. Recent studies have shown that periodontitis can affect the central nervous system by activating inflammatory mediators in the brain. However, only a few studies have examined the association between periodontitis and bipolar disorder. Here, we aimed to review the current evidence on the association between periodontal diseases and bipolar disorder, its potential mechanisms, and future research directions. Studies so far suggested that periodontal diseases were more common in patients with bipolar disorder than in the general population. Patients with bipolar disorder generally have poor oral hygiene owing to poor self-care, smoking, alcohol abuse, and the effects of psychotropic medications. Proposed mechanisms underlying this association include the effects of inflammatory mediators, direct invasion of oral microbiota, modulation of the neurotransmitter system, and impact on the vagus nerve and hypothalamus-pituitary- adrenal axis. Additional clinical studies examining the prevalence of periodontal diseases and their association with the clinical features of bipolar disorder are necessary. Clinical studies targeting the treatment of periodontal diseases for primary or secondary prevention of bipolar disorder are warranted.