• Psychological Stress: A Predisposing and Exacerbating Factor in Periodontitis

      Spector, Anna M.; Postolache, Teodor T.; Akram, Faisal; Scott, Alison J.; Wadhawan, Abhishek; Reynolds, Mark A. (Springer Science and Business Media B.V., 2020-08-20)
      Purpose of Review: This review focuses on recent advances in our understanding of the interactions between psychological stress, the immune system, and periodontitis, including the dynamic role of host stress responses in altering immune function, altering the oral microbiome and biofilm formation, and promoting local and systemic disease progression. Recent Findings: Within the context of periodontal health and disease, stress leads to an impairment of effective antimicrobial defense, shifts in oral microbiome profiles toward more pathogenic gene expression and taxa composition, increased translocation, and biofilm formation. The link between stress and periodontitis is multiform and includes hypothalamic–pituitary–adrenal (HPA) axis and catecholamine activation, production of immune mediators of inflammation and, clinically, syndromes of depression, bipolar disorder, anxiety disorders, and sleep-wake disorders. Summary: Psychological stress appears to be an important modifiable risk factor for the development and progression of periodontitis and other periodontal diseases. © 2020, The Author(s).
    • Toxoplasma gondii, Suicidal Behavior, and Intermediate Phenotypes for Suicidal Behavior

      Postolache, Teodor T; Wadhawan, Abhishek; Rujescu, Dan; Hoisington, Andrew J; Dagdag, Aline; Baca-Garcia, Enrique; Lowry, Christopher A; Okusaga, Olaoluwa O; Brenner, Lisa A (Frontiers Media S.A., 2021-06-11)
      Within the general literature on infections and suicidal behavior, studies on Toxoplasma gondii (T. gondii) occupy a central position. This is related to the parasite's neurotropism, high prevalence of chronic infection, as well as specific and non-specific behavioral alterations in rodents that lead to increased risk taking, which are recapitulated in humans by T. gondii's associations with suicidal behavior, as well as trait impulsivity and aggression, mental illness and traffic accidents. This paper is a detailed review of the associations between T. gondii serology and suicidal behavior, a field of study that started 15 years ago with our publication of associations between T. gondii IgG serology and suicidal behavior in persons with mood disorders. This "legacy" article presents, chronologically, our primary studies in individuals with mood disorders and schizophrenia in Germany, recent attempters in Sweden, and in a large cohort of mothers in Denmark. Then, it reviews findings from all three meta-analyses published to date, confirming our reported associations and overall consistent in effect size [ranging between 39 and 57% elevation of odds of suicide attempt in T. gondii immunoglobulin (IgG) positives]. Finally, the article introduces certain links between T. gondii and biomarkers previously associated with suicidal behavior (kynurenines, phenylalanine/tyrosine), intermediate phenotypes of suicidal behavior (impulsivity, aggression) and state-dependent suicide risk factors (hopelessness/dysphoria, sleep impairment). In sum, an abundance of evidence supports a positive link between suicide attempts (but not suicidal ideation) and T. gondii IgG (but not IgM) seropositivity and serointensity. Trait impulsivity and aggression, endophenotypes of suicidal behavior have also been positively associated with T. gondii seropositivity in both the psychiatrically healthy as well as in patients with Intermittent Explosive Disorder. Yet, causality has not been demonstrated. Thus, randomized interventional studies are necessary to advance causal inferences and, if causality is confirmed, to provide hope that an etiological treatment for a distinct subgroup of individuals at an increased risk for suicide could emerge.