Iron deficiency and cognition

Abstract

Iron deficiency is the most prevalent nutritional disorder in the world. One of the most worrying consequences of iron deficiency in children is the alteration of behaviour and cognitive performance. In iron-deficient children, striking behavioural changes are observed, such as reduced attention span, reduced emotional responsiveness and low scores on tests of intelligence. Animal studies on nutritional iron deficiency show effects on learning ability that parallel the human studies. Despite the obvious confounding impact of socioeconomic factors, there is a wealth of clinical, biochemical and neuropathological research that shows that iron deficiency can exert a direct deleterious effect on learning and the brain, and that this can occur with normal haemoglobin levels. Nutritional iron replacement therapy readily corrects haematological iron status in iron-deficient children within 2-3 weeks, but behavioural problems persist for several months or years. This resi stance to iron-replacement therapy and its long-term consequences on learning are not quite understood. A recent study in infants showed that the cognitive deficits in iron deficiency was reversed with iron supplementation. This finding provides evidence that in some settings cognitive deficits are not always permanent. Although further research is required to address these issues, several studies support the theory that iron sufficiency throughout the course of brain development is critical to normal brain iron and behavioural outcome.