Toxoplasma gondii in Individuals With Schizophrenia: Association With Clinical and Demographic Factors and With Mortality

The Stanley Research Center at the Sheppard Pratt Health System, 6501 North Charles Street, Baltimore, MD 21204, USA.
Schizophrenia Bulletin (Impact Factor: 8.45). 06/2007; 33(3):737-40. DOI: 10.1093/schbul/sbm005
Source: PubMed


Increased rates of exposure to Toxoplasma gondii have been found in individuals with schizophrenia as compared with control groups, but the correlates of Toxoplasma exposure in schizophrenia have not been defined.
We measured IgG class antibodies to Toxoplasma gondii in 358 individuals with schizophrenia. We correlated Toxoplasma antibody status with clinical and demographic variables and examined the effect of Toxoplasma seropositivity on mortality in a follow-up period of up to 5 years.
Individuals with schizophrenia who had serological evidence of Toxoplasma infection were more likely to be female but did not differ in age, race, total symptom score, or other demographic or clinical characteristics. However, we found that serological evidence of Toxoplasma was associated with a significantly increased risk of dying of natural causes during the follow-up period (Cox proportional hazard ratio of 4.70; 95% confidence interval, 1.27-17.31, P = .020) adjusted for age, gender, and other clinical and demographic variables.
Toxoplasma infection may confer an increased risk for mortality from natural causes in schizophrenia. An understanding of the pathogenesis of Toxoplasma infections in individuals with schizophrenia might lead to new approaches to the management of this disorder.

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    • "In terms of gender difference, we found differences between male and female patients with schizophrenia disorder (P = 0.009). Similar results, that is, higher seropositivity in schizophrenic women than in schizophrenic men, were also reported by Dickerson et al. [48]. "
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    ABSTRACT: Objective. The aim of the present study was to examine the relationship between Toxoplasma gondii and Toxocara spp. infections in patients with schizophrenia disorder. Method. A total of 100 patients with schizophrenia disorder and 95 healthy individuals participated in the study. Participants were tested for the presence of anti-T. gondii and anti-Toxocara spp. antibodies by ELISA and Western blotting. Data were analyzed using Chi-square test and Fisher 9 s exact test. Results. There were no differences in T. gondii IgG seroprevalence between patients with schizophrenia and healthy individuals (P = 0.1), but there were differences in seroprevalence between males and females with schizophrenia (P = 0.009). In contrast, Toxocara spp. IgG seroprevalence was greater in patients with schizophrenia disorder than in healthy individuals (P = 0.02), but there were no differences in seroprevalence between men and women with schizophrenia (P = 0.5). Finally, there were no differences in seroprevalence of T. gondii or Toxocara spp. IgG among different subtypes of schizophrenia, various age groups, residential area, or clinical course of treatment (P > 0.05). Conclusion. The present study suggests that patients with schizophrenia disorder are at elevated risk of Toxocara spp. infection. Moreover, contamination with T. gondii is a risk factor for schizophrenia in women.
    Full-text · Article · Apr 2014
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    • "Latent toxoplasmosis, although frequently dismissed as asymptomatic and clinically unimportant, alters host behavior in both humans and rodents (Burkinshaw et al., 1953; Flegr, 2007; Kannan and Pletnikov, 2012; Webster et al., 2006; Wilson et al., 1980). In addition and possibly related, a growing number of epidemiological studies associate persistent T. gondii infection with an increased likelihood of developing schizophrenia (Dickerson et al., 2007; Torrey et al., 2012). Notably, elevated anti-T. "
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    ABSTRACT: Toxoplasma gondii, an intracellular protozoan parasite, is a major cause of opportunistic infectious disease affecting the brain and has been linked to an increased incidence of schizophrenia. In murine hosts, infection with T. gondii stimulates tryptophan degradation along the kynurenine pathway (KP), which contains several neuroactive metabolites, including 3-hydroxykynurenine (3-HK), quinolinic acid (QUIN) and kynurenic acid (KYNA). As these endogenous compounds may provide a mechanistic connection between T. gondii and the pathophysiology of schizophrenia, we measured KP metabolites in both the brain and periphery of T. gondii-treated C57BL/6 mice 8 and 28days post-infection. Infected mice showed early decreases in the levels of tryptophan in the brain and serum, but not in the liver. These reductions were associated with elevated levels of kynurenine, KYNA, 3-HK and QUIN in the brain. In quantitative terms, the most significant increases in these KP metabolites were observed in the brain at 28days post-infection. Notably, the anti-parasitic drugs pyrimethamine and sulfadiazine, a standard treatment of toxoplasmosis, significantly reduced 3-HK and KYNA levels in the brain of infected mice when applied between 28 and 56days post-infection. In summary, T. gondii infection, probably by activating microglia and astrocytes, enhances the production of KP metabolites in the brain. However, during the first two months after infection, the KP changes in these mice do not reliably duplicate abnormalities seen in the brain of individuals with schizophrenia.
    Full-text · Article · Dec 2013 · Schizophrenia Research
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    • "Dickerson et al. have examined antibodies to T. gondii in 358 patients with schizophrenia and followed-up these peoples up to 5 years. The results indicated that the overall mortality rate was 8.6% for schizophrenia patients who were seropositive to Toxoplasma compared with 1.7% for seronegative schizophrenia patient (P < 0.003) (59). "
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    ABSTRACT: Toxoplasmosis is one of the most common parasitic diseases worldwide. Although estimated that one third of the world's population are infected with Toxoplasma gondii, but the most common form of the disease is latent (asymptomatic). On the other hand, recent findings indicated that latent toxoplasmosis is not only unsafe for human, but also may play various roles in the etiology of different mental disorders. This paper reviews new findings about importance of latent toxoplasmosis (except in immunocompromised patients) in alterations of behavioral parameters and also its role in the etiology of schizophrenia and depressive disorders, obsessive-compulsive disorder, Alzheimer's diseases and Parkinson's disease, epilepsy, headache and or migraine, mental retardation and intelligence quotients, suicide attempt, risk of traffic accidents, sex ratio and some possible mechanisms of T. gondii that could contribute in the etiology of these alterations.
    Full-text · Article · Mar 2012 · Iranian Journal of Parasitology
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