Abstract

Introduction: Many studies have found an association between Toxoplasma gondii seropositivity and behavioral and cognitive changes in animal models and in humans. In addition, early findings have suggested an association between T. gondii seropositivity and Alzheimer's disease (AD). We sought to determine whether there is an association between T. gondii seropositivity and AD as well as cognitive functioning (including memory, working memory, processing speed, language functioning, executive functioning) in a large, well-characterized sample of subjects with AD and matched controls without dementia. Method: Using ELISA assays, we determined anti-T. gondii IgG antibody titers in 114 control subjects and in 105 subjects diagnosed with AD through an Alzheimer's Disease Research Center. We compared the seroprevalence between the two groups using propensity score matching (PSM). We also compared associations between T. gondii seropositivity and cognitive functioning using both PSM and linear regressions. Results: We found no differences between groups in age, ethnicity, or gender. Education and socioeconomic status was slightly higher in the control group. Using PSM, we did not find a significant difference in having AD due to T. gondii seropositivity between the two groups. Using PSM, we found T. gondii seropositivity was associated with worse performance on the WAIS-R Digit Symbol test. Within the AD group, we found T. gondii seropositivity was associated with worse performance on the WAIS Block Design and Trail Making B tests. Conclusion: In this sample, we found no evidence of an association between T. gondii seropositivity and AD in a larger study than previous studies. We found evidence of a negative association between processing speed and T. gondii seropositivity as well as a negative association between processing speed, executive functioning, and T. gondii seropositivity in those with AD.

Degree

PhD

College and Department

Family, Home, and Social Sciences; Psychology