"Latent" infection with Toxoplasma gondii: Association with trait aggression and impulsivity in healthy adults

Background: Latent chronic infection with Toxoplasma gondii (T. gondii), a common neurotropic pathogen, has been previously linked with suicidal self-directed violence (SSDV). We sought to determine if latent infection with T.gondii is associated with trait aggression and impulsivity, intermediate phenotypes for suicidal behavior, in psychiatrically healthy adults. Methods: Traits of aggression and impulsivity were analyzed in relationship to IgG antibody seropositivity for T.gondii and two other latent neurotropic infections, herpes simplex virus 1 (HSV1) and cytomegalovirus (CMV). One thousand community-residing adults residing in the Munich metropolitan area with no Axis I or II conditions by SCID for DSM-IV (510 men, 490 women, mean age 53.6±15.8, range 20-74). Plasma samples were tested for IgG antibodies to T.gondii, HSV-1 and CMV by ELISA. Self-reported ratings of trait aggression scores (Questionnaire for Measuring Factors of Aggression [FAF]) and trait impulsivity (Sensation-Seeking Scale-V [SSS-V]) were analyzed using linear multivariate methods. Results: T.gondii IgG seropositivity was significantly associated with higher trait reactive aggression scores among women (p<.01), but not among men. T.gondii-positivity was also associated with higher impulsive sensation-seeking (SSS-V Disinhibition) among younger men (p<.01) aged 20-59 years old (median age=60). All associations with HSV-1 and CMV were not significant. Conclusions: Aggression and impulsivity, personality traits considered as endophenotypes for SSDV, are associated with latent T.gondii infection in a gender and age-specific manner, and could be further investigated as prognostic and treatment targets in T.gondii-positive individuals at risk for SSDV.