A controlled prospective study of Toxoplasma gondii infection in individuals with schizophrenia: Beyond seroprevalence

Abstract

Toxoplasma gondii (TG) infection has been reported to be more frequent in schizophrenia. The interaction of the lifelong persisting parasite with the host's immune system involves T-cell/interferon-gamma-induced degradation of tryptophan and provides a challenge to the host well beyond a possible role in the etiology of schizophrenia. The hypothesis we tested in this study was that TG infection may be more frequent (serofrequency) and/or more intense (serointensity) in patients with schizophrenia or major depression compared with psychiatrically healthy controls. In addition, these measures are associated with the clinical course. We did a cross-sectional, prospective investigation of individuals with schizophrenia (n = 277) and major depression (n = 465) admitted to our department (2002)(2003)(2004)(2005) and of healthy controls (n = 214), with all groups adjusted for age and geographic home region. Serofrequency was comparable between the groups, but serointensity was significantly higher in the patients. In individuals with schizophrenia, serointensity was significantly positively associated with C-reactive protein levels and leukocyte counts, and firstepisode patients yielded significantly higher serotiters. Immunomodulatory medication was associated with decreased serotiters. In addition, the route of infection appears to differ between patients and controls. Thus, our results support increased host responses to TG infection in the patients, as well as increased titers in first-episode patients with schizophrenia; this may relate to the shifted T-helper 1/2 status described in these patients. Therefore, we suggest that TG infection, particularly in individuals with schizophrenia, is an important environmental factor in the interaction between psychiatric vulnerability, genetic background, immunomodulation, and the neurotransmitter systems.

Differences in onset of disease and severity of psychopathology between toxoplasmosis‐related and toxoplasmosis‐unrelated schizophrenia

“…Or Toxoplasma-inhibitory features of antipsychotic and mood stabilising drugs can be utilised in treatment of Toxoplasma-infected patients (64,65) to modify the course of disease (66). Anti-Toxoplasma immune response modulation also warrants further attention because it may improve the clinical course of schizophrenia or prevent chronicity in first-episode patients (67).…”

Toxoplasma gondii: 25 years and 25 major advances for the field

“…In humans, there have been several reports of correlations between being sero-positive for Toxoplasma and certain behaviors (e.g., risk of being in a car accident (Flegr et al, 2002)) or psychiatric conditions (e.g., schizophrenia ((Destounis, 1966; Derouin et al, 2002; Hinze-Selch et al, 2007)), some dating back many years. Unfortunately, teasing out all other possible confounders will be an enormous challenge.…”

Toxoplasma gondii‐induced neuronal alterations

“…Interestingly, the results revealed not only personality disturbances but also prominent gender and age differences (45, 52-55). Intriguingly, classical psychiatric diseases such as schizophrenia, mood disorders, psychosis, and self-directed violence were also linked to toxoplasmosis, as Toxoplasma seropositivity was elevated in neuropsychiatric patients compared to heathy volunteers in numerous studies (56)(57)(58)(59)(60)(61)(62). Although it is difficult to establish a clear mechanistic correlation, the timing (childhood or adulthood onset of the psychiatric disease) and the route of infection (cyst or oocyst) could also vary between the cases and thus influence differently the development of such mental disorders.…”