Toxoplasma gondii Infection and Self-directed Violence in MothersToxoplasma Gondii and Self-directed Violence.
CONTEXT Two studies based on clinical samples have found an association between Toxoplasma gondii infection and history of suicide attempt. To our knowledge, these findings have never been replicated in a prospective cohort study. OBJECTIVE To examine whether T gondii-infected mothers have an increased risk of self-directed violence, violent suicide attempts, and suicide and whether the risk depends on the level of T gondii IgG antibodies. DESIGN Register-based prospective cohort study. Women were followed up from the date of delivery, 1992 to 1995 until 2006. SETTING Denmark. PARTICIPANTS A cohort of 45 788 women born in Denmark whose level of Toxoplasma-specific IgG antibodies was measured in connection with child birth between 1992 and 1995. MAIN OUTCOME MEASURES Incidence rates of self-directed violence, violent suicide attempts, and suicide in relation to T gondii seropositivity and serointensity. RESULTS T gondii-infected mothers had a relative risk of self-directed violence of 1.53 (95% CI, 1.27-1.85) compared with noninfected mothers, and the risk seemed to increase with increasing IgG antibody level. For violent suicide attempts, the relative risk was 1.81 (95% CI, 1.13-2.84) and for suicide, 2.05 (95% CI, 0.78-5.20). A similar association was found for repetition of self-directed violence, with a relative risk of 1.54 (95% CI, 0.98-2.39). CONCLUSION Women with a T gondii infection have an increased risk of self-directed violence.
Available from: Motamed Elsayed Mahmoud
- "As a mood disorder , depression is characterized by loss of interest, pleasure, cognitive function, sleep, appetite, and energy . Retrospective studies have referred to T. gondii seroprevalence in psychiatric disorders such as schizophrenia, bipolar mood disorder , and self-directed violence  . However, the causal link between T. gondii and bipolar disease is controversial, with some studies showing that T. gondii seroprevalence is not associated with major depressive disorder, generalized-anxiety disorder, or panic disorder . "
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ABSTRACT: Although Toxoplasma gondii (T. gondii) infection is relevant to many psychiatric disorders, the fundamental mechanisms of its neurobiological correlation with depression are poorly understood. Here, we show that reactivation of chronic infection by an immunosuppressive regimen caused induction of depressive-like behaviors without obvious sickness symptoms. However, the depression-related behaviors in T. gondii-infected mice, specifically, reduced sucrose preference and increased immobility in the forced-swim test were observed at the reactivation stage, but not in the chronic infection. Interestingly, reactivation of T. gondii was associated with production of interferon-gamma and activation of brain indoleamine 2, 3-dioxygenase, which converts tryptophan to kynurenine and makes it unavailable for serotonin synthesis. Furthermore, serotonin turnover to its major metabolite, 5-hydroxyindoleacetic acid, was also enhanced at the reactivation stage. Thus, enhanced tryptophan catabolic shunt and serotonin turnover may be implicated in development of depressive-like behaviors in mice with reactivated T. gondii.
- "Furthermore , T. gondii has been associated with suicidal self-directed violence (SSDV: a term that includes death by suicide, and history of suicide attempts [the most important predictor of suicide]). Nonfatal SSDV (NF-SSDV) has also been found to be associated with T. gondii IgG seropositivity in patients with schizophrenia (Okusaga et al., 2011), patients with mood disorders (Arling et al., 2009), in samples with mixed psychiatric disorders versus healthy controls (Yagmur et al., 2010; Zhang et al., 2012), and in a prospective cohort study of Danish women (Pedersen et al., 2012). The association of T. gondii seropositivity with death by SSDV was also reported in women of post-menopausal age (Ling et al., 2011). "
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ABSTRACT: Toxoplasma gondii (T. gondii) chronic infection and elevated kynurenine (KYN) levels have been individually associated with non-fatal suicidal self-directed violence (NF-SSDV). We aimed to test the hypothesis that the association between T. gondii seropositivity and history of NF-SSDV would be stronger in schizophrenia patients with high plasma KYN levels than in those with lower KYN levels. We measured anti-T. gondii IgG antibodies and plasma KYN in 950 patients with schizophrenia, and used logistic regression to evaluate the relationship between NF-SSDV and KYN in patients who were either seropositive or seronegative for T. gondii. For those with KYN levels in the upper 25th percentile, the unadjusted odds ratio for the association between NF-SSDV history and KYN in T. gondii seropositive patients was 1.63 (95% CI 1.01 to 2.66), p = 0.048; the adjusted odds ratio was 1.95 (95% CI 1.15 to 3.30), p = 0.014. Plasma KYN was not associated with a history of NF-SSDV in T. gondii seronegative patients. The results suggest that T. gondii and KYN may have a nonlinear cumulative effect on the risk of NF-SSDV among those with schizophrenia. If confirmed by future longitudinal studies, this result is expected to have both theoretical and clinical implications for the prevention and treatment of suicidal behavior.
Available from: Kelly Marie Salisbury
- "In turn this would increase an imbalance in serotonin, which would exacerbate a depressive state, potentially resulting in inward-directed violence. Pedersen et al. (2012) also found that infected women were twice as likely to commit suicide, and 1.5 times more likely to attempt suicide, than uninfected women. Further evidence as to the role of T. gondii in depression arose from Yagmur et al. (2010) who found a 48% prevalence rate of T. gondii infection among patients admitted to hospital following a suicide attempt, in relation to 23% in those admitted for other reasons. "
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DESCRIPTION: Since 1908,Toxoplasma gondii was largely thought to only cause physical disease in humans. The congenital, ocular, acute and chronic effects of toxoplasmosis were well documented throughout the medical community. Later research revealing the importance of felids in the lifecycle of T. gondii shed light on the role of humans and pathways of infection. However, the recent discovery of a potential link between some mental disorders and T. gondii infection has resulted in a surge of research into the neurological and psychological effects. Such research has revealed a potential role in the development of schizophrenia, depression and suicidal behaviour. In spite of this, very little research was undertaken into whether T. gondii prevalence has a role in causing outward-directed aggression, namely homicide. One small study of 20 European countries found a correlation between the two factors. This study aimed to expand upon such research by including a wider data, comprising of European, Asian, Oceanian, African and American populations. It was found that there was a significant, strong positive correlation between T. gondii prevalence and homicide count across all 114 countries included. However, findings per region differed, resulting in significant, strong positive correlations in the Americas, Europe and Asia, a non-significant, positive correlation in Africa and a non-significant negative correlation in Oceania. It was surmised that these results, while indicative of a relationship, still required further research in order to establish a direction. Implications on existing research, potential avenues for further research and potential social and ethical implications of the findings were discussed.
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