Association between latent toxoplasmosis and major depression, generalised anxiety disorder and panic disorder in human adults
Latent infection with the apicomplexan Toxoplasma gondii (Nicolle et Manceaux, 1908) has been associated with schizophrenia, bipolar disorder and self-harm behaviour. However, the potential relationship between T. gondii immunoglobulin G antibody (IgG) seropositivity and generalised-anxiety disorder (GAD) and panic disorder (PD) has not been investigated. The associations between serum reactivity to T. gondii and major depressive disorder (MDD), GAD and PD were evaluated in a total sample of 1 846 adult participants between the ages of 20 and 39 years from the United States Center for Disease Control's National Health and Nutrition Examination Survey (NHANES). Approximately 16% of the overall sample was seropositive for T. gondii and 7% of the sample met criteria for MDD, 2% for GAD and 2% for PD. There were no significant associations between T. gondii IgG seroprevalence and MDD (OR = 0.484, 95% CI = 0.186-1.258), GAD (OR = 0.737, 95% CI = 0.218-2.490) or PD (OR = 0.683, 95% CI = 0.206-2.270) controlling for sex, ethnicity, poverty-to-income ratio and educational attainment. However, limited evidence suggested a possible association between absolute antibody titres for T. gondii and GAD and PD but not MDD. Toxoplasma gondii seroprevalence was not associated with MDD, GAD or PD within the context of the limitations of this study, although there may be an association of T. gondii serointensity with and GAD and PD, which requires further study.