Association of infection withToxoplasma gondiiandToxocaraon cognitive function among US adults aged 60 and over, NHANES 2011–2014

Abstract

BackgroundToxoplasma gondiiandToxocaraare common parasites that infect humans globally. Our aim was to examine the relationship betweenT. gondiiandToxocarainfection and cognition.MethodsMultivariate logistic regression was used to test the association ofT. gondiiandToxocaraseropositivity on indices of cognitive function (a word list learning trial with delayed recall from the Consortium to Establish a Registry for Alzheimer’s Disease, an animal fluency test (AFT) and a digit symbol substitution test (DSST)) among 2643 adults aged 60 years and older in the 2011–2014 National Health and Nutrition Examination Survey.ResultsSeropositivity toT. gondiiorToxocarawere both associated with lower scores in all three cognitive function measures examined in univariate analyses. Except for the DSST, these associations were not significant after adjustment for age, gender, race and Hispanic origin, poverty level, education, US birth status, depression and hypertension. On stratification to account for significant interactions,Toxocaraseropositivity was associated with worse scores on the AFT among those born outside the USA, worse scores on the DSST among those aged 60–69 years, female, Hispanic and with a high school diploma or less. Lower DSST scores withToxocarainfection was greater for adults living below compared with at or above the poverty level.ConclusionsSeropositivity to these parasites, particularly toToxocara, may be associated with diminished cognitive performance in certain subgroups of older adults.