Background: Helicobacter pylori (H. pylori) infection is associated with cognitive deficits in humans, an association potentially mediated or moderated by folate concentration or inflammation.
Materials and methods: We used the National Health and Nutrition Examination Survey (NHANES) datasets to examine whether folate concentration or inflammation mediates or moderates the relationship between H. pylori and cognitive function. Models were performed using linear, Poisson, and zero-inflated Poisson regression, and we performed separate analyses for groups aged 20-59 and 60-90 years with sample sizes ranging from 700 to 1700.
Results: We did not find evidence of mediation in either age group. In the 20- to 59-year group, interactions between H. pylori and ferritin (p values ranging from .004 to .039) were associated with worse processing speed, better working memory, and worse reaction time. Interactions between H. pylori and fibrinogen (p values ranging from .023 to .045), C-reactive protein (CRP) (p = .023), and the inflammatory index (p = .045) were associated with worse processing speed. In 60- to 90-year-olds, H. pylori interacted with ferritin and the inflammatory index to predict fewer mathematical errors (p values of .036 and .023). Interactions with folate (p values of .016 and .006) and C-reactive protein (p values ranging from <.001 to .048) were inconsistent in directionality.
Conclusions: In this dataset, representative of the US population, inflammation and folate concentrations moderated but did not mediate the association between H. pylori seropositivity and cognition.
Keywords: Helicobacter pylori; C-reactive protein; cognition; ferritin; folate; inflammation.
© 2016 John Wiley & Sons Ltd.