Abstract
Infecting approximately one-third of the world’s human population, Toxoplasma gondii has been associated with cognitive function. Here, we sought to further characterize the association between Toxoplasma gondii and cognitive function in a community sample of adults aged approximately 40 to70 years. Using adjusted linear regression models, we found associations of Toxoplasma gondii seropositivity with worse reasoning (b = -.192, p < .05) and matrix pattern completion (b = -.681, p < .01), of higher anti-Toxoplasma gondii p22 antibody levels with worse reasoning (b = -.078, p < .01) and slower Trails (numeric) performance (b = 5.962, p < .05), of higher anti-Toxoplasma gondii sag1 levels with worse reasoning (b = -.081, p < .05) and worse matrix pattern completion (b = -.217, p < .05), and of higher mean of the anti-Toxoplasma gondii p22 and sag1 levels with worse reasoning (b = -.112, p < .05), slower Trails (numeric) performance (b = 9.195, p < .05), and worse matrix pattern completion (b = -.245, p < .05). Neither age nor educational attainment moderated associations between the measures of Toxoplasma gondii seropositivity or serointensity. Sex, however, moderated the association between the sag1 titer and digit-symbol substitution and the association between the mean of the p22 and sag1 levels and digit-symbol substitution, and income moderated the association between Toxoplasma gondii seropositivity and numeric memory and the association between the p22 level and symbol-digit substitution. Based on the available neuropsychological tasks in this study, Toxoplasma gondii seropositivity and serointensity were associated with some aspects of poorer executive function in adults.
Highlights
Accumulating evidence indicates that some infectious diseases might be associated with cognitive function and dementia [1,2,3]
Toxoplasma gondii is a parasite that reproduces in cats but that can infect other animals and humans
Toxoplasma gondii has an affinity for the brain and infection results in a long-term immune response that may have negative effects
Summary
Accumulating evidence indicates that some infectious diseases might be associated with cognitive function and dementia [1,2,3]. Meta-analyses have shown associations between Chlamydia pneumoniae and dementia and between spirochete infection and dementia [4], and a systematic umbrella review found suggestive evidence of an association between herpesviridae viruses and Alzheimer’s disease [5], findings that together suggest the importance of considering the associations between microbial pathogens and both cognitive decline and dementia [3]. In addition to possibly influencing human behavior [8,9,10] and showing an association with schizophrenia [11], some [12,13,14,15,16,17,18] but not all [19,20,21] evidence suggests that T. gondii in humans is adversely associated with cognitive function. The results of a recent meta-analysis showed an association between T. gondii and dementia [22]
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