The Relationship Between Toxoplasma Gondii Infection and Mood Disorders in the Third National Health and Nutrition Survey

Biological Psychiatry. Available online 10 February 2012.




Toxoplasma gondii (T. gondii) is a neurotropic protozoan parasite that causes persistent infection in humans. A substantial literature suggests that schizophrenia is associated with increased seroprevalence of T. gondii, but a possible link of the parasite with mood disorders has not been as thoroughly investigated.

Methods
The association of Toxoplasma-specific immunoglobulin G results with mood disorder outcomes were examined in 7440 respondents from the third National Health and Nutrition Survey. Regression models were adjusted for numerous potential confounders, including tobacco smoking and C-reactive protein levels.

Results
- No statistically significant associations were found between T. gondii seroprevalence and a history of major depression, severe major depression, dysthymia, or dysthymia with comorbid major depression- all p values were > .05, including analysis stratified by gender.
- There was a significant relationship between T. gondii seroprevalence and bipolar disorder type I for respondents in which both manic and major depression symptoms were reported.

Conclusions
In a population-based sample, T. gondii seroprevalence is not elevated in unipolar mood disorders but is higher in a subset of respondents with a history of bipolar disorder type 1.