gondii infection profoundly alters the manner in which rodents perceive and respond to stressful stimuli ( Webster,

2007), only two previous studies have investigated whether T. gondii is related to human anxiety ( Groer et al., 2011 and Miman et al., 2010). Groer et al. assessed whether T. gondii seropositivity NU7441 chemical structure and serointensity were associated with anxiety among a cohort of pregnant women enrolled in a study of postpartum thyroiditis, as assessed by the Profile of Mood Disorder States (POMS), a non-clinical diagnostic screening instrument ( Groer et al., 2011). Similar to our study, the authors found a positive correlation between T. gondii serointensity and the POMS tension-anxiety subscale score (r = 0.31, p < 0.04). However, use of the POMS limited Groer et al. to scoring participants on a 5-point anxiety scale, whereas our study utilized buy Cobimetinib a validated survey instrument that enabled us to assign subjects clinical diagnoses of GAD. In addition, generalizability of their findings were limited to pregnant women enrolled in a study of postpartum thyroiditis ( Groer et al., 2011), whereas we included a subset of individuals drawn from a population-based sample in our study. To our knowledge, only one prior study has examined associations between T. gondii and any anxiety disorder as diagnosed by DSM-IV criteria ( Miman et al., 2010). In a case-control study of 142

subjects, Miman et al. found that individuals with psychiatrist-diagnosed

obsessive–compulsive disorder (OCD) were more likely to be seropositive for T. gondii than were healthy controls (chi-square 12.12, p < 0.01). However, the authors did not report continuous or categorical antibody levels. Overall, our study is the first to demonstrate that, in addition to a positive association between T. gondii seropositivity and GAD, there may be a graded relationship between T. gondii IgG antibody levels and odds of GAD. While the underlying PTK6 mechanisms by which T. gondii specifically affects GAD but not PTSD or depression remain uncertain, potential anxiogenic pathways include histopathological, immunological, and neuromodulatory alterations ( Webster, 2007). Rodent studies have failed to uncover a highly selective tropism of T. gondii for a specific brain region; tissue cysts have been detected throughout the brain, with observed distribution patterns varying both between ( Berenreiterova et al., 2011, Haroon et al., 2012 and Vyas et al., 2007) and within ( Berenreiterova et al., 2011) studies. However, cyst density does not appear homogenous across brain regions ( Berenreiterova et al., 2011), while a recent study suggests that cysts may preferentially persist and increase in number in limbic regions known to mediate anxiety, including the amygdala and hypothalamus ( Haroon et al., 2012). In vivo studies of chronically infected rodents indicate that T.