Toxoplasma gondii infection and common mental disorders in the Finnish general population

We investigated whether T. gondii seropositivity is associated with 12-month depressive, anxiety and alcohol use disorders and current depressive symptoms and whether inflammation, measured by C-reactive protein (CRP) level, explains these associations.

Health 2000 study (BRIF8901), conducted in years 2000-2001, is based on a nationally representative sample of Finns aged 30 and above, with 7112 participants and 88.6% response rate. DSM-IV depressive, anxiety and alcohol use disorders were assessed with the Composite International Diagnostic Interview and depressive symptoms with the Beck Depressive Inventory (BDI-21). We used logistic regression to investigate the association of T. gondii seropositivity with mental disorders and linear regression with BDI-21 scores.

T. gondii seroprevalence was significantly associated with 12-month generalized anxiety disorder but not with other anxiety, depressive or alcohol use disorders. T. gondii seropositivity was associated with higher BDI-21 scores (beta 0.56, 95% CI 0.12-1.00, P = 0.013) and with having a comorbid depressive and anxiety disorder (OR 1.86, 95% CI 1.16-2.97, P = 0.010). Higher CRP levels were associated with these outcomes and with T. gondii seropositivity, but adjusting for CRP did not change the effect of T. gondii seropositivity.

Cross-sectional study design with no information on the timing of T. gondii infection.

T. gondii seropositivity is associated with generalized anxiety disorder, depressive symptoms and comorbid depressive and anxiety disorders, which is not mediated by inflammation.