Latent <em>Toxoplasma gondii</em> Infection Moderates the Association Between the C677T MTHFR Polymorphism and Cognitive Function in U.S. Adults

• Main Author: Berrett, Andrew Nathan
• Format: Others
• Published: BYU ScholarsArchive 2018
• Subjects: Toxoplasma gondii; MTHFR; folate; cognitive function; reaction time
• Online Access: https://scholarsarchive.byu.edu/etd/7245; https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=8245&amp;context=etd

Sufficient blood concentrations of folate and the products from its metabolism are necessary for several cellular functions. The C677T MTHFR polymorphism, present in over half of the U.S. population, reduces the efficiency of folate metabolism and has been linked to the onset of multiple psychiatric disorders and cognitive decline. The intracellular parasite Toxoplasma gondii can infect the human brain and is associated with increased prevalence of psychiatric disorders and cognitive decline. In vitro studies have found that Toxoplasma gondii may salvage unmetabolized folate from host cells. Since the C677T MTHFR polymorphism and infection by Toxoplasma gondii both affect folate metabolism or availability, I used data from the third National Health and Nutrition Examination Survey to test the hypothesis that latent toxoplasmosis and the C677T MTHFR polymorphism interact to predict worse cognitive functioning in U.S. adults. I found a statistically significant interaction effect between Toxoplasma gondii infection and the C677T MTHFR polymorphism in predicting performance on a test of reaction time. Subjects who were not infected with Toxoplasma gondii experienced declines in reaction time with the presence of one or two alleles for the C677T MTHFR polymorphism. However, this association was reversed for subjects who were seropositive for Toxoplasma gondii. No interaction effects were observed when predicting performance on a test of processing speed or a test of short term memory. In conclusion, these findings suggest that the co-occurrence of Toxoplasma gondii infection and the C677T MTHFR polymorphism maybe associated with improved reaction time.