• Suicide Attempts and Perceived Social Support among Chinese Drug Users: The Mediating Role of Self-Esteem and Depression

      Deng, Yali; Li, Xuemeng; Liu, Liu; Chui, Wing Hong (MDPI AG, 2020-12-30)
      Suicidal behavior is a severe problem among drug users. This study examines influential factors related to suicide attempts and analyzes possible mediators of the relationship between perceived social support and suicide attempts amongst Chinese drug users under compulsory institutional drug treatment. Taking perceived social support as the independent variable, we found that the relationship between suicide attempts and perceived social support is mediated by self-esteem as a protective factor and depression as a risk factor. Path analysis shows that self-esteem contributes relatively more to the indirect effects than depression does, accounting for 31.1% and 24.2% of the total effect, respectively. Generally speaking, the findings of this study point to an urgent need for addressing suicide attempts among Chinese drug users while treating self-esteem as the protective factor that deserves as substantial attention as depression receives. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
    • 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.