Beyond the association. T oxoplasma gondii in schizophrenia, bipolar disorder, and addiction: systematic review and meta‐analysis

Objective To perform a meta‐analysis on studies reporting prevalence of T oxoplasma gondii ( T . gondii ) infection in any psychiatric disorder compared with healthy controls. Our secondary objective was to analyze factors possibly moderating heterogeneity. Method A systematic search was performed to identify studies into T . gondii infection for all major psychiatric disorders versus healthy controls. Methodological quality, publication bias, and possible moderators were assessed. Results A total of 2866 citations were retrieved and 50 studies finally included. Significant odds ratios ( OR s) with I g G antibodies were found in schizophrenia ( OR 1.81, P  < 0.00001), bipolar disorder ( OR 1.52, P  = 0.02), obsessive–compulsive disorder ( OR 3.4, P  < 0.001), and addiction ( OR 1.91, P  < 0.00001), but not for major depression ( OR 1.21, P  = 0.28). Exploration of the association between T . gondii and schizophrenia yielded a significant effect of seropositivity before onset and serointensity, but not I g M antibodies or gender. The amplitude of the OR was influenced by region and general seroprevalence. Moderators together accounted for 56% of the observed variance in study effects. After controlling for publication bias, the adjusted OR (1.43) in schizophrenia remained significant. Conclusion These findings suggest that T . gondii infection is associated with several psychiatric disorders and that in schizophrenia reactivation of latent T . gondii infection may occur.