Antibodies to Toxoplasma gondii in Patients With Schizophrenia: A Meta-Analysis

Abstract

Recent studies have linked infectious agents to schizophrenia. The largest number of studies has involved the analysis of Toxoplasma gondii; these studies were subjected to a meta-analysis. Published articles and abstracts were identified by searches of MEDLINE, Ovid, and Google Scholar; by a search of Chinese publications; through letters to researchers; and by visiting China. Published and unpublished controlled studies that used serological methods for measuring T. gondii antibodies to assess inpatients and/or outpatients diagnosed with schizophrenia were selected for analysis, and source documents were translated as needed. Forty-two studies carried out in 17 countries over 5 decades were identified; 23 of these (6 unpublished) met selection criteria. The combined odds ratio (OR) was 2.73 (95% confidence interval, 2.10 to 3.60; chi-square with 1 df 263; P < .000001). Seven studies that included only patients with first-episode schizophrenia (OR 2.54) did not differ significantly from 16 studies that included patients in all clinical phases (OR 2.79). The results suggest that individuals with schizophrenia have an increased prevalence of antibodies to T. gondii. This association is consistent with other epidemiological studies as well as with animal studies. Although the OR of 2.73 is modest, it exceeds that for genetic or other environmental factors identified to date and suggests that Toxoplasma is in some way associated with a large number of cases of schizophrenia. If an etiological association can be proven, it would have implications for the design of measures for the prevention and treatment of this disease.

The protozoan Toxoplasma gondii: neurotoxicological relevance beyond the typical clinical pictures

“…The authors stated that schizophrenia was 2.7 times more frequent in marker-positive persons than in marker-negative persons. These figures are in line with a previously published meta-analysis on the association of T. gondii and schizophrenia, based on 23 included studies, showing an odds ratio of 2.73 (Torrey et al 2007). …”

Inhibition of Toxoplasma gondii and Plasmodium falciparum Infections in Vitro by NSC3852, a Redox Active Antiproliferative and Tumor Cell Differentiation Agent

“…Latent infections persist as encysted T. gondii in the brain and other tissues. Toxoplasma gondii exposure has been associated with cognitive and behavioral dysfunction, including schizophrenia (Lindova et al, 2006;Flegr, 2007;Mortensen et al, 2007;Torrey et al, 2007;Torrey and Yolken, 2007). Toxoplasma gondii infections are also recognized as a risk factor for cardiovascular disease (Portugal et al, 2004;Yazar et al, 2006;Franco-Paredes et al, 2007).…”

“…Toxoplasma gondii infections are also recognized as a risk factor for cardiovascular disease (Portugal et al, 2004;Yazar et al, 2006;Franco-Paredes et al, 2007). Based on antibody titers, it has been estimated that 20-30% of people worldwide have been infected by T. gondii, and, regionally, the prevalence can rise to 80% or higher (Jeannel et al, 1988;Saygi, 2001;Francisco Fde et al, 2006;Jones et al, 2007;Torrey et al, 2007). Toxoplasma gondii control measures and treatment options are rather limited considering the impact of this pathogen on human health.…”

Toxoplasmosis and psychosis: environment makes a difference

“…In another meta-analysis comparing 23 studies which includes patients with both first episode schizophrenia and those in all clinical phases there was an increased prevalence of T. gondii antibodies among individuals with schizophrenia [31]. In another meta-analysis of eight studies, seven of which were done on serological markers, and one from post-mortem brain tissue, there was a significant association between T. gondii infection and schizophrenia.…”