Negative confounding by essential fatty acids in methylmercury neurotoxicity associations

TY - JOUR

T1 - Negative confounding by essential fatty acids in methylmercury neurotoxicity associations

AU - Choi, Anna L

AU - Mogensen, Ulla Brasch

AU - Bjerve, Kristian S

AU - Debes, Frodi

AU - Weihe, Pal

AU - Grandjean, Philippe

AU - Budtz-Jørgensen, Esben

N1 - Copyright © 2014 Elsevier Inc. All rights reserved.

PY - 2014/3/1

Y1 - 2014/3/1

N2 - BACKGROUND: Methylmercury, a worldwide contaminant of fish and seafood, can cause adverse effects on the developing nervous system. However, long-chain n-3 polyunsaturated fatty acids in seafood provide beneficial effects on brain development. Negative confounding will likely result in underestimation of both mercury toxicity and nutrient benefits unless mutual adjustment is included in the analysis.METHODS: We examined these associations in 176 Faroese children, in whom prenatal methylmercury exposure was assessed from mercury concentrations in cord blood and maternal hair. The relative concentrations of fatty acids were determined in cord serum phospholipids. Neuropsychological performance in verbal, motor, attention, spatial, and memory functions was assessed at 7 years of age. Multiple regression and structural equation models (SEMs) were carried out to determine the confounder-adjusted associations with methylmercury exposure.RESULTS: A short delay recall (in percent change) in the California Verbal Learning Test (CVLT) was associated with a doubling of cord blood methylmercury (-18.9, 95% confidence interval [CI]=-36.3, -1.51). The association became stronger after the inclusion of fatty acid concentrations in the analysis (-22.0, 95% confidence interval [CI]=-39.4, -4.62). In structural equation models, poorer memory function (corresponding to a lower score in the learning trials and short delay recall in CVLT) was associated with a doubling of prenatal exposure to methylmercury after the inclusion of fatty acid concentrations in the analysis (-1.94, 95% CI=-3.39, -0.49).CONCLUSIONS: Associations between prenatal exposure to methylmercury and neurobehavioral deficits in memory function at school age were strengthened after fatty acid adjustment, thus suggesting that n-3 fatty acids need to be included in analysis of similar studies to avoid underestimation of the associations with methylmercury exposure.

AB - BACKGROUND: Methylmercury, a worldwide contaminant of fish and seafood, can cause adverse effects on the developing nervous system. However, long-chain n-3 polyunsaturated fatty acids in seafood provide beneficial effects on brain development. Negative confounding will likely result in underestimation of both mercury toxicity and nutrient benefits unless mutual adjustment is included in the analysis.METHODS: We examined these associations in 176 Faroese children, in whom prenatal methylmercury exposure was assessed from mercury concentrations in cord blood and maternal hair. The relative concentrations of fatty acids were determined in cord serum phospholipids. Neuropsychological performance in verbal, motor, attention, spatial, and memory functions was assessed at 7 years of age. Multiple regression and structural equation models (SEMs) were carried out to determine the confounder-adjusted associations with methylmercury exposure.RESULTS: A short delay recall (in percent change) in the California Verbal Learning Test (CVLT) was associated with a doubling of cord blood methylmercury (-18.9, 95% confidence interval [CI]=-36.3, -1.51). The association became stronger after the inclusion of fatty acid concentrations in the analysis (-22.0, 95% confidence interval [CI]=-39.4, -4.62). In structural equation models, poorer memory function (corresponding to a lower score in the learning trials and short delay recall in CVLT) was associated with a doubling of prenatal exposure to methylmercury after the inclusion of fatty acid concentrations in the analysis (-1.94, 95% CI=-3.39, -0.49).CONCLUSIONS: Associations between prenatal exposure to methylmercury and neurobehavioral deficits in memory function at school age were strengthened after fatty acid adjustment, thus suggesting that n-3 fatty acids need to be included in analysis of similar studies to avoid underestimation of the associations with methylmercury exposure.

KW - Attention

KW - Child

KW - Cohort Studies

KW - Denmark

KW - Fatty Acids, Essential

KW - Fatty Acids, Omega-3

KW - Female

KW - Fetal Blood

KW - Food Contamination

KW - Humans

KW - Infant, Newborn

KW - Male

KW - Mental Recall

KW - Methylmercury Compounds

KW - Neuropsychological Tests

KW - Neurotoxins

KW - Pregnancy

KW - Prenatal Exposure Delayed Effects

KW - Seafood

U2 - 10.1016/j.ntt.2014.02.003

DO - 10.1016/j.ntt.2014.02.003

M3 - Journal article

C2 - 24561639

SN - 0892-0362

VL - 42

SP - 85

EP - 92

JO - Neurotoxicology and Teratology

JF - Neurotoxicology and Teratology

ER -