Association between Toxoplasma gondii infection and anxiety disorders: a case-control study in North of Iran

Anxiety disorders are a leading cause of disability worldwide, influenced by genetic, environmental, and infectious factors. Toxoplasma gondii (T. gondii), a neurotropic parasite, has been implicated in various psychiatric disorders, but its association with anxiety remains unclear. This study aimed to evaluate the relationship between T. gondii infection and anxiety disorders in a case-control study. We recruited 90 anxiety disorder patients and 90 healthy controls from Shahid Yahyanezhad Hospital, Babol, Iran. Anxiety severity was assessed using the Beck Anxiety Inventory. Serum samples were analyzed for anti-T. gondii IgG antibodies via ELISA. Statistical analyses included chi-square tests and logistic regression models, adjusting for potential confounders. The seroprevalence of T. gondii was lower in anxiety patients (65.55%; 95% CI 54.8–75.2%) than in controls (82.22%; 95%CI 72.7–89.5%). Univariable (OR = 0.41, 95% CI: 0.21–0.82) and multivariable (OR = 0.37, 95% CI: 0.17–0.79) analyses suggested a significant protective effect of T. gondii against anxiety. This association was particularly notable in moderate anxiety cases (OR = 0.37, 95% CI: 0.14–0.96). Higher antibody levels correlated with lower anxiety scores, reinforcing this potential protective role. T. gondii infection may reduce anxiety disorder risk, particularly in moderate cases. These findings challenge conventional views on T. gondii’s neuropsychiatric effects and warrant further research into the underlying mechanisms.