Iron deficiency and cognition

Lena Hulthén

doi:10.3402/fnr.v47i3.1486

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.

Highlights

Iron deficiency continues to be the single most common nutritional deficiency and the main cause of anaemia in infancy and childhood
The reported prevalence of iron-deficiency anaemia in young children varies in different populations, depending in part on the case definition used, with estimates ranging from 10% in Western societies to around 50% in less developed societies (1)
There is a history of more than 30 years of efforts to document the effects of iron deficiency on developmental delays in young children and infants (3 Á/6)

Summary

Introduction

Iron deficiency continues to be the single most common nutritional deficiency and the main cause of anaemia in infancy and childhood. After the iron-deficient rats were placed on a control diet for 3 weeks, there was a return to normal haemoglobin levels, but the learning capacity remained significantly reduced. It must be recognized, that there are certain limitations in using animal models. Altered behaviour and development are among the most worrying concerns about iron deficiency in infancy, especially because this nutrient deficiency is most prevalent in the period between 6 and 24 months of age Because this age range coincides with a period of maximal brain growth and the unfolding of many neurodevelopmental processes, several investigators have focused on the question of CNS effects of iron deficiency.

Hulthen L

Findings

Conclusion