Interaction of iron deficiency anemia and neurofunctions in cognitive development

Effect of Iron-Deficiency Anemia on Cognitive Skills and Neuromaturation in Infancy and Childhood

Iron-deficiency anemia in infancy has been consistently shown to negatively influence performance in tests of psychomotor development. In most studies of short-term follow-up, lower scores did not improve with iron therapy, despite complete hematologic replenishment.

The negative impact on psychomotor development of iron-deficiency anemia (IDA) in infancy has been well documented in more than a dozen studies during the last two decades. Two studies will be presented here to further support this assertion. Additionally, we will present some data referring to longer follow-up at 5 and 10 years as well as data concerning recent descriptions of the neurologic derangements that may underlie these behavioral effects.

To evaluate whether these deficits may revert after long-term observation, a cohort of infants was re-evaluated at 5 and 10 years of age. Two studies have examined children aged 5 years who had anemia as infants using comparable tools of cognitive development showing persisting and consistent important disadvantages in those who were formerly anemic. These tests were better predictors of future achievement than psychomotor scores. These children were again examined at 10 years and showed lower school achievement and poorer fine-hand movements. Studies of neurologic maturation in a new cohort of infants aged 6 months included auditory brain stem responses and naptime 18-lead sleep studies. The central conduction time of the auditory brain stem responses was slower at 6, 12, and 18 months and at 4 years, despite iron therapy beginning at 6 months. During the sleep-wake-fulness cycle, heart-rate variability—a developmental expression of the autonomic nervous system—was less mature in anemic infants. The proposed mechanisms are altered auditory-nerve and vagal-nerve myelination, respectively, as iron is required for normal myelin synthesis.

Serum Level of Some Minerals during Three Trimesters of Pregnancy in Iranian Women and Their Newborns: A Longitudinal Study

Concentrations of various trace elements are altered during pregnancy with changes in the mother's physiology and the requirements of growing fetus. The aim of the present longitudinal study was to learn the changes of micronutrients Iron (Fe), Calcium (Ca), zinc (Zn) Magnesium (Mg) and copper (Cu) of pregnant woman and their relations with newborns levels. Serum levels of iron, calcium, zinc, magnesium and copper of 162 pregnant women and their newborns were determined by an inductively couple plasma mass spectrometer (ICP/MS). The results showed that majority (41 %) of pregnant women were in age group 26-36 years 55 % had high school and diploma levels of education and the total income ranged between 3 and 5 Rials million per month There was significant difference in iron levels during first, second and third trimesters, 76.0 ± 17.8, 63.5 ± 15.2 and 70.1 ± 14.4 μg/dl respectively. Significant difference was shown in zinc levels 79.5 ± 15, 74.5 ± 16.1, and 65.3 ± 14.9 μg/dl during three trimesters. Copper levels during pregnancy were significantly different (130.9 ± 43.5, 172.0 ± 38.94, 193.2 ± 28.5 μg/dl. The serum levels of calcium and magnesium during pregnancy were constant (Ca: 8.96 ± 0.48, 8.86 ± 0.47, 8.91 ± 0.42 mg/dl and Mg: 2.10 ± 0.21, 2.08 ± 0.28, 2.09 ± 0.29 mg/dl). Results showed that 13 % of pregnant women had hypocalcaemia and hypomagnesaemia. Thirty eight percent and 42 % of pregnant women had iron and zinc deficiency respectively. In this study, unlike zinc, no pregnant women were found deficient in serum copper levels. Calcium, iron, zinc, copper and magnesium levels in the newborn's cord blood were 8.93 ± 0.43, 106.0 ± 26.1, 85.35 ± 16.6, 57.04 ± 13.8 and 1.99 ± 0.27 mg/dl respectively. In the present study the levels of iron and zinc in cord blood were higher than the levels of iron and zinc in maternal serum. The mean level of copper in cord blood serum in the current study was lower than maternal values. The mean serum calcium and magnesium in the serum cord blood and in the serum of the pregnant women were similar.

Why iron deficiency is important in infant development

Infants who experience iron deficiency during the first 6-12 mo of life are likely to experience persistent effects of the deficiency that alter functioning in adulthood. A lack of sufficient iron intake may significantly delay the development of the central nervous system as a result of alterations in morphology, neurochemistry, and bioenergetics. Depending on the stage of development at the time of iron deficiency, there may be an opportunity to reverse adverse effects, but the success of repletion efforts appear to be time dependent. Publications in the past several years describe the emerging picture of the consequences of iron deficiency in both human and animal studies. The mechanisms for iron accumulation in the brain and perhaps redistribution are being understood. The data in human infants are consistent with altered myelination of white matter, changes in monoamine metabolism in striatum, and functioning of the hippocampus. Rodent studies also show effects of iron deficiency during gestation and lactation that persist into adulthood despite restoration of iron status at weaning. These studies indicate that gestation and early lactation are likely critical periods when iron deficiency will result in long-lasting damage.

Risk factors for moderate to severe anemia among children in Benin and Mali: insights from a multilevel analysis

BACKGROUND

Anemia currently affects 2 billion people throughout the world. Although the immediate causes of anemia among children are known (including malnutrition and infections), the importance of contextual determinants and their relationships with individual effects have rarely been explored.

OBJECTIVE

To identify anemia risk factors at the individual, household, and community levels among Beninese and Malian children, using simple and multilevel regression methods.

METHODS

An analysis was undertaken of nationally representative data collected in 2001 in Benin (n = 2,284) and Mali (n = 2,826) by the Demographic and Health Surveys. Sixteen potential risk factors for anemia were considered at the individual, household, and community levels. Comparative analyses were carried out using simple and multilevel logistic regression models.

RESULTS

Simple and multilevel logistic regression analyses yielded broadly similar results. Risk factors for moderate to severe anemia included incomplete immunization, stunted growth, recent infection, absence of bednet, low household living standard, rural residency (Mali), low maternal education, and low community development index (Benin). In addition, multilevel analysis indicated a clustering level of anemia in communities (intraclass correlation) of 14% and 19% in Benin and Mali, respectively.

CONCLUSIONS

Risk factors for child anemia appeared at all three levels (individual, household and community). Community-level clustering seemed to be low. Therefore, interventions to address anemia need not be village- or region-specific. Identifying a successful and replicable program is now a priority in child survival endeavors. It is likely that such a program would include a focus on improving immunization coverage, increased bednet usage, and reduced protein-energy malnutrition.

Cellular iron concentrations directly affect the expression levels of norepinephrine transporter in PC12 cells and rat brain tissue

Neurological development and functioning are adversely affected by iron deficiency in early life. Iron-deficient rats are known to have elevations in extracellular DA and NE, suggesting alterations in reuptake of these monoamines. To explore possible mechanisms by which cellular iron concentrations may alter NE transporter functioning, we utilized NET expressing PC12 cells and iron-deficient rats to explore the relationship between NET protein and mRNA expression patterns and iron concentrations. Treatment of PC12 with the iron chelator, desferrioxamine mesylate (DFO, 50 microM for 24 h), significantly decreased [3H] NE uptake by more than 35% with no apparent change in Km. PC12 cells exposed to increasing concentrations of DFO (25-100 microM) exhibited a dose response decrease in [3H] NE uptake within 24 h (38-73% of control) that paralleled a decrease in cellular NET protein content. Inhibition of protein synthesis with cycloheximide resulted in NET disappearance rates from DFO-treated cells greatly exceeding the rate of loss from control cells. RT-PCR analysis revealed only a modest decrease in NET mRNA levels. Rat brain locus ceruleus and thalamus NET mRNA levels were also only modestly decreased (10-15%) despite a 40% reduction in regional brain iron. In contrast, NET proteins levels in thalamus and locus ceruleus were strongly affected by regional iron deficiency with high correlations with iron concentrations (r > 0.94 and r > 0.80 respectively). The present findings demonstrate that NET protein concentrations and functioning are dramatically reduced with iron deficiency; the modest effect on mRNA levels suggests a stronger influence on NET trafficking and degradation than on protein synthesis.