Neurophysiologic and neurobehavioral evidence of beneficial effects of prenatal omega-3 fatty acid intake on memory function at school age

Abstract

Background: The beneficial effects of prenatal and early postnatal intakes of omega-3 (n-3) polyunsaturated fatty acids (PUFAs) on cognitive development during infancy are well recognized. However, few studies have examined the extent to which these benefits continue to be evident in childhood.

Objective: The aim of this study was to examine the relation of n-3 PUFAs and seafood-contaminant intake with memory function in school-age children from a fish-eating community.

Design: In a prospective, longitudinal study in Arctic Quebec, we assessed Inuit children (n = 154; mean age: 11.3 y) by using a continuous visual recognition task to measure 2 event-related potential components related to recognition memory processing: the FN400 and the late positive component (LPC). Children were also examined by using 2 well-established neurobehavioral assessments of memory: the Digit span forward from Wechsler Intelligence Scales for Children, 4th edition, and the California Verbal Learning Test-Children's Version.

Results: Repeated-measures analyses of variance revealed that children with higher cord plasma concentrations of docosahexaenoic acid (DHA), which is an important n-3 PUFA, had a shorter FN400 latency and a larger LPC amplitude; and higher plasma DHA concentrations at the time of testing were associated with increased FN400 amplitude. Cord DHA-related effects were observed regardless of seafood-contaminant amounts. Multiple regression analyses also showed positive associations between cord DHA concentrations and performance on neurobehavioral assessments of memory.

Conclusion: To our knowledge, this study provides the first neurophysiologic and neurobehavioral evidence of long-term beneficial effects of n-3 PUFA intake in utero on memory function in school-age children.

FIGURE 1

Examples of items presented during the continuous recognition memory task. Children pressed the new button to the first presentation of an item and the old button to each subsequent presentation of that item. Lags represent the number of items intervening between 2 subsequent presentations of the same item.

FIGURE 2

Grand average event-related potentials (ERPs) for the continuous recognition task (n = 154). Dotted lines represent ERPs for correctly identified new pictures, and continuous lines represent ERPs for correctly identified old pictures. Frontocentral electrodes showed a negative deflection that occurred between 300 and 500 ms and reached a maximal amplitude at the Fz electrode, which is referred to as the FN400 component, and was followed by positive activity in the 500–800-ms interval and reached a maximal amplitude at the parietal electrodes, which is referred to as the late positive component (LPC). Both components showed more positive voltage for old than for new pictures, which is a phenomenon known as the FN400 and LPC old/new effects.

FIGURE 3

Grand average event-related potentials (ERPs) for participants with low cord docosahexaenoic acid (DHA) concentrations (<3.42% of fatty acids; n = 75; gray lines) compared with high cord DHA concentrations (≥3.43% of fatty acids; n = 74; black lines). Dotted lines represent ERPs for correctly identified new pictures, and continuous lines represent ERPs for correctly identified old pictures. In the high-DHA group, the FN400 component (Fz) reached its peak earlier, and the late positive component (LPC; Pz) was larger.

FIGURE 4

Mean (±SD) differences in FN400 latency at Fz averaged for new and old stimuli by exposure group. Exposure groups were created by using the median values of each exposure variable. Latencies were adjusted for child age at testing, maternal age at delivery, and breastfeeding duration. *,**Significant differences between groups in pairwise post hoc comparisons (ANCOVA): *P < 0.05, **P < 0.01. DHA, docosahexaenoic acid; Hg, mercury; PCB 153, polychlorinated biphenyl congener 153.

FIGURE 5

Mean (±SD) differences in late positive component (LPC) amplitude at Pz averaged for new and old stimuli by exposure group. Exposure groups were created by using the median values of each exposure variable. Amplitudes were adjusted for maternal education, socioeconomic status, maternal Raven's score, tobacco during pregnancy, current blood lead concentrations, and maternal age at delivery. *,**Significant differences between groups in pairwise post hoc comparisons (ANCOVA): *P < 0.05, **P < 0.01. DHA, docosahexaenoic acid; Hg, mercury; PCB 153, polychlorinated biphenyl congener 153.

FIGURE 6

Mean (±SD) differences in FN400 amplitude at Fz averaged for new and old stimuli by exposure group. Exposure groups were created by using the median values of each exposure variable. Amplitudes were adjusted for child sex, socioeconomic status, tobacco during pregnancy and cord lead concentrations. *,**Significant differences between groups in pairwise post hoc comparisons (ANCOVA): *P < 0.05, **P < 0.01. DHA, docosahexaenoic acid; Hg, mercury; PCB 153, polychlorinated biphenyl congener 153.