One-Carbon Metabolism in Nepalese Infant-Mother Pairs and Child Cognition at 5 Years Old

BACKGROUND One-carbon metabolism (OCM) refers to the transfer of methyl groups central to DNA methylation and histone modification. Insufficient access to methyl donors and B-vitamin cofactors affects epigenetic maintenance and stability, and when occurring in early life may impact future health and neurodevelopment. OBJECTIVE The objective of this study was to examine the relative associations between one-carbon metabolites in Nepalese mother-infant pairs and child cognition measured at 5 y of age. METHODS This is a cross-sectional study from Bhaktapur, Nepal, in a population at high risk of subclinical B-vitamin deficiencies and cumulative infection burden. Venous blood samples from 500 mother-infant pairs were collected when the infants were 2 to 12 mo old, and metabolite concentrations measured by microbiological assays and GC-tandem MS. We re-enrolled 321 of these children at 5 y and assessed cognition by the Ages and Stages Questionnaire, 3rd edition, and subtests from the Developmental Neuropsychological Assessment, 2nd edition (NEPSY-II). The associations of the independent metabolites or unobserved metabolic phenotypes (identified by latent class analysis) with the cognitive outcomes were estimated by seemingly unrelated regression. We explored direct and indirect relations between the OCM pathway and the cognitive outcomes using path analysis. RESULTS Infant cystathionine concentration was inversely associated with 4 cognitive outcomes (standardized βs ranging from -0.22 to -0.11, P values from