Impact of Fetal-Neonatal Iron Deficiency on Recognition Memory at 2 Months of Age

Abstract

Objective: To assess the effects of fetal-neonatal iron deficiency on recognition memory in early infancy. Perinatal iron deficiency delays or disrupts hippocampal development in animal models and thus may impair related neural functions in human infants, such as recognition memory.

Study design: Event-related potentials were used in an auditory recognition memory task to compare 2-month-old Chinese infants with iron sufficiency or deficiency at birth. Fetal-neonatal iron deficiency was defined 2 ways: high zinc protoporphyrin/heme ratio (ZPP/H > 118 μmol/mol) or low serum ferritin (<75 μg/L) in cord blood. Late slow wave was used to measure infant recognition of mother's voice.

Results: Event related potentials patterns differed significantly for fetal-neonatal iron deficiency as defined by high cord ZPP/H but not low ferritin. Comparing 35 infants with iron deficiency (ZPP/H > 118 μmol/mol) to 92 with lower ZPP/H (iron-sufficient), only infants with iron sufficiency showed larger late slow wave amplitude for stranger's voice than mother's voice in frontal-central and parietal-occipital locations, indicating the recognition of mother's voice.

Conclusions: Infants with iron sufficiency showed electrophysiological evidence of recognizing their mother's voice, whereas infants with fetal-neonatal iron deficiency did not. Their poorer auditory recognition memory at 2 months of age is consistent with effects of fetal-neonatal iron deficiency on the developing hippocampus.

Figure 1

Layout of the EGI 64-channel sensor net and the four regions of interest. The merged ERP waveforms are displayed for each region of interest and group. ID, iron deficiency; IS, iron sufficiency.

Figure 2

Mean LSW amplitude (±SE) in frontal-central and parietal-occipital locations by condition and iron group (* p < .05). There were two interactions involving iron group: condition × hemisphere × group (F (1, 119) = 5.17, p < .05, η_p² = 0.04) and condition × front-back × hemisphere × group (F (1, 119) = 6.02, p < .05, η_p² = 0.05). For infants with sufficiency, there was a significant condition × front-back interaction (F (1, 85) = 5.77, p < .05, η_p² = 0.06). Follow-up analyses indicated LSW amplitude in the frontal-central location was more negative in the stranger vs. mother condition (F (1, 85) = 5.56, p < .05, η_p² = 0.06), whereas LSW amplitude in the parietal-occipital location was more positive in the stranger vs. mother condition (F (1, 85) = 4.91, p < .05, η_p² = 0.06). For infants with iron deficiency, the condition effect was not significant in any region of interest.