Iron deficiency and behavior: criteria for testing causality

Article Abstract:

Many research studies have found a relationship between iron deficiency (ID) and poor intellectual or behavioral performance. In a typical study, children were given various tests measuring their cognitive or mental and behavioral abilities and their blood iron levels were evaluated; the two factors were then analyzed to see if there was a relationship between them. Scientists have theorized that ID may, in some way, cause poor test scores, but the studies have not demonstrated a cause-and-effect relationship. This controversy will continue until large, well-designed studies produce evidence supporting or refuting a causal relationship. To show that ID affects cognitive performance, ID must precede poor performance in time. Also, all other factors that might be involved must be eliminated. For example, some believe that socioeconomic conditions, such as the financial or educational resources of the family, cause poor cognitive performance regardless of the children's iron status. This theory suggests that ID, poor socioeconomic conditions, and low test scores all coexist but the cause-and-effect relationship does not involve ID. The authors describe the way future research studies should be conducted in order to answer the question of whether or not ID and cognitive performance are related. If it is shown that ID causes intellectual and behavioral deficits, public health policy should then respond with efforts to prevent and correct ID through iron supplementation programs. Iron supplementation would serve to support children's intellectual and behavioral development and this goal would be used to justify funding for such public health programs.

Methods, Testing, Behavioral assessment of children, Childhood behavioral assessment

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Effects of iron deficiency on attention and learning processes in preschool children: Bandung, Indonesia

Article Abstract:

Researchers have collected evidence suggesting that iron deficiency interferes with attention span and learning in children. A distinction is made between iron-depletion (ID) and iron-deficiency anemia (IDA). IDA is a more severe form of this nutritional disorder. In both ID and IDA, the hemoglobin concentration in red blood cells is reduced and, as a result, the red blood cells cannot carry adequate amounts of oxygen to body tissues. This study evaluated 205 preschool children in Indonesia. They were divided into three categories: iron-replete, or normal; iron-depleted, or ID; and iron-deficient anemic, or IDA. Of the ID and IDA children, half received iron supplements of ferrous sulfate for eight weeks and the other half received placebos, inactive substances. The ID and IDA children who received ferrous sulfate showed desirable increases in their blood iron levels following treatment. The blood tests of IDA children were no longer in the anemic range. The cognitive or mental tests demonstrated that IDA had an adverse effect on mental processes, specifically those involved with visual attention and the learning of concepts. The deficits in these processes were successfully reversed by the eight weeks of iron supplementation. ID and normal children did not differ in their test performance, suggesting that iron depletion is not severe enough to alter cognitive functioning, whereas iron-deficiency anemia does produce alterations.

Evaluation, Physiological aspects, Indonesia, Iron compounds, Ferrous sulfate

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Summary and conclusions of the International Conference on Iron Deficiency and Behavioral Development, October 10-12, 1988

Article Abstract:

The authors summarize findings from an international conference on research concerning iron deficiency (ID) and child development. Some studies focused on the cognitive, or mental, and behavioral performance of children from infancy to adolescence; others used animal models to investigate the topic. As with any association between two conditions, an important question is whether one condition causes or influences the other, or whether a third factor influences both. Various environmental and family characteristics that frequently coexist with ID could also explain the cognitive deficits that have been identified in anemic children. The authors conclude that there is sufficient evidence to suggest that ID does cause less than optimal child development. Some investigators discovered that anemic children given iron supplements over a period of time improved on learning and motor ability tests. This evidence supports widespread public health efforts to prevent and treat ID in all children. More research is needed to establish the mechanism by which ID affects the brain, and how long iron therapy should continue. There are data which also suggest that some of the damage to cognitive processes associated with ID may be permanent.

Prevention, Iron, Iron (Metal), Motor ability in children, Nutrition disorders in children

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