Toxoplasmosis in schizophrenia, bipolar and depressive disorders versus healthy controls: Immunologic and epidemiologic findings

Individuals with schizophrenia may have increased prevalence and seropositivity of Toxoplasma gondii (Tg), a chronic neurotropic parasitic infection modulating among others relevant neurotransmitter systems (1,2). Thus, we investigated whether this is specific to schizophrenia and whether psychotic exacerbations are associated with activity of Tg infection. Specific serology and in vitro investigations on peripheral blood cells are performed in individuals with schizophrenia, bipolar or depressive disorder and in healthy controls.

Compared to controls, the prevalence of Tg infection is significantly increased in subjects with schizophrenia or depressive disorder older than 40 years. For the first time, we demonstrated that during acute infection or exacerbation specific in vitro proliferative response is suppressed paralleled by acute exacerbation of psychosis. Further investigations on TH1/TH2 response by 4 colour FACS scan and a placebo controlled antitoxoplasmatic treatment trial in seropositive acutely exacerbated schizophrenic and depressive patients are under way.

Our preliminary results support the notion that infection with Tg might play a role not only in schizophrenia but also in major depression.

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Yolken RH et al. Clin Infect Dis 2001; 32:842–844.

Acknowledgement: This study is supported by a grant of the ‘Treatment Trial for Schizophrenia Program’ of the Stanley Medical Research Institute.