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There is concern that high iron uptake during the critical period of early brain development carries potential risks, especially for nonanemic infants. This study examined the neurocognitive functioning of 16-year-olds who were nonanemic as infants and received iron supplementation. We studied 562 Chilean adolescents (M 16.2 years; 52.7% female) who participated in a randomized controlled iron supplementation trial in infancy. Between 6 and 12 months, 346 consumed an iron-fortified formula (12.7 Fe mg/L) or, if primarily breastfed, liquid vitamins with 15 mg elemental iron as ferrous sulfate, and 216 consumed unmodified cow milk without iron or liquid vitamins without iron if primarily breastfed. Compared to adolescents in the no-added iron condition in infancy, those in the iron-supplemented condition had poorer visual-motor integration, quantitative reasoning skills, and incurred more errors on neurocognitive tasks. Consuming larger amounts of iron-fortified formula in infancy was associated with lower arithmetic achievement. Of adolescents who had high hemoglobin at 6 months (Hb ≥ 125 g/L), those in the iron supplemented condition had poorer performance on arithmetic, quantitative reasoning, and response inhibition tests than those in the no-added iron condition. Of adolescents who had marginally low 6-month hemoglobin (Hb > 100 and < 110 g/L), those who received no-added iron incurred more errors on a visual searching task than those in the iron-supplemented condition. The physiologic need for iron during the period of rapid and critical brain development in young infants should be considered vis-à-vis the risks associated with supplementing nonanemic infants with high levels of iron. Clinical Trials number: NCT01166451 [ABSTRACT FROM AUTHOR]

Objective: This study examined how the lower cognitive skills in children who consumed iron-fortified formula in infancy relate to outcomes in young adulthood. Methods: Participants were 443 Chilean young adults (M age = 21.2y, 55% female) who took part in a randomized controlled iron-deficiency anemia preventive trial during infancy (6–12 m). Slightly over half of participants (n = 237) received iron-fortified formula (12.7 mg/L) and 206 received a low-iron formula (2.3 mg/L). Spatial memory, IQ, and visual-motor integration were measured at age 10, and neurocognition, emotion regulation, educational level, and attainment of adult developmental milestones were assessed at age 21. Results: Consumption of iron-fortified formula in infancy was associated with poorer performance on neurocognitive tests in childhood, and these effects related to poorer neurocognitive, emotional, and educational outcomes in young adulthood. Dosage effects associated with consumption of iron-fortified formula were found for lower educational attainment and, marginally, slower mental processing. Those who received iron-fortified formula and had low age 10 cognitive abilities performed most poorly on neurocognitive tests at age 21. Conclusion: Findings suggest that the long-term development of infants who consume iron-fortified formula may be adversely affected. Clinical Trials number: NCT01166451 [ABSTRACT FROM AUTHOR]

Objective: To determine the relationship between iron deficiency (or iron-deficient, ID) and neural correlates of recognition memory depending on ID timing (gestation vs. infancy) and infant age at testing (9 vs. 18 months). Study design: Event-related potentials (ERP) were used in a visual recognition memory task (mother vs. stranger face) to compare healthy term infants according to iron status at birth and 9 months. Fetal-neonatal ID was defined as cord serum ferritin < 75 µg/l or zinc protoporphrin/heme ratio > 118 µmol/mol, postnatal ID as ≥ 2 abnormal iron measures at 9 months with normal cord-blood iron status, and iron-sufficient as not ID at birth or 9 months. Recognition of mother faces was measured by negative component (Nc) and late slow wave (LSW). These ERP components reflect attention and memory updating processes, respectively. Results: All groups showed differences in Nc amplitude elicited by mother and stranger faces at 9 months. At 18 months, only postnatal ID and iron-sufficient groups showed condition differences in Nc amplitude. However, the 2 groups were different in the involved brain regions. For LSW, only the 2 ID groups showed condition differences in amplitude at 9 months. At 18 months, condition differences were not observed in any group. Conclusions: This study indicates that the timing of ID in early life (fetal-neonatal vs. postnatal) modulates the impact of ID on recognition memory. Such impact also varies depending on the age of infants at testing (9 vs. 18 months). [ABSTRACT FROM AUTHOR]

Objective: The aim of the current study was to examine the unique and joint contributions of iron deficiency, iron supplementation, and psychosocial stress in infancy and stress in adolescence to neurocognitive functioning in adolescence. Methods: The current study (N = 796; Mage = 14.4y) involved a prospective cohort of low- and middle-socioeconomic status adolescents in Santiago, Chile. As infants, they had participated in an iron supplementation trial. Infant iron status was assessed at 12–18 months, and mothers answered questions about family psychosocial stress at 6–12 months and in adolescence (maternal depressive symptoms, home support for child development, stressful life events, father absence, socioeconomic status, and parental education). Neurocognitive functioning was assessed in adolescence using the Balloon Analogue Risk Task, Stockings of Cambridge, Trail Making Test, Purdue Pegboard Test, and Wisconsin Card Sorting Test. Results: Greater psychosocial stress in infancy predicted less risk-taking, poorer planning abilities and fluid cognition, and slower processing speed in adolescence. Iron deficiency anemia in infancy predicted less risk-taking. Greater adolescent psychosocial stress predicted difficulties in set-shifting. There were no interactions between infant psychosocial stress and iron deficiency predicting adolescent neurocognitive functioning. Conclusion: These results suggest that interventions to reduce infant psychosocial stress may be more likely to prevent multiple neurocognitive deficits in adolescence than interventions to reduce infant iron deficiency. [ABSTRACT FROM AUTHOR]