What do we know about the long‐term cognitive effects of iron‐deficiency anemia in infancy?

The topic of iron deficiency and its impact during development is critical as it is thought to affect 20 to 25% of the worldwide population. A 2001 review of existing research concluded that iron deficiency has a negative impact on cognition, behavior, and motor skills that can have long term implications. When it comes to brain regions, it impacts areas associated with spatial navigation, such as the hippocampus. One concern is that this relationship can be confounded by external factors, such as low socioeconomic background. The issue of the affect of iron deficiency is not without controversy. Some argue that its potential long-term negative consequences on cognitive impairment and motor skills are far from either causal or conclusive, and could be largely motivated by a desire to promote the use of supplements. The study by Algar in et al. brings the research upto-date by investigating whether having iron-deficiency anemia (IDA) in infancy affects cognitive inhibition in the long term. They recruited children who were healthy fullterm infants, with no perinatal complications, and no acute or chronic illnesses, but were identified as either having iron-deficiency anemia (IDA) or not at 6, 12, or 18 months. Participants were given an oral iron supplement for a minimum of 6 months and had normal venous hemoglobin concentrations at the end of the study. They were tested again for the present study when they were aged 10 years. Less than 5% of the sample had IDA (defined as low venous hemoglobin concentrations) and were not included in the analyses. Crucially, the researchers ensured that there was no difference in socio-economic status between groups, so that the findings would be relatively free from this influence. The researchers focused primarily on inhibitory control, which is a key aspect of cognition – associated with decision-making and addictive behavior. The results indicated that despite receiving iron treatment in infancy and the absence of IDA at 10 years old, children who had IDA during infancy performed significantly worse in a test of cognitive inhibition. The present research also added to existing research by identifying smaller a P300 amplitude during event-related potentials recordings. This profile of the P300 is consistent with research associating this area with working memory performance. Working memory – the conscious processing of information – is increasingly recognized as one of the most important aspects of intelligence. This fundamental cognitive skill is deeply connected to a great variety of human experience – from our childhood, to our old age, from our education, to our mental health as adults. The implications of the present research are that IDA can contribute to long-term cognitive impairments that may jeopardize the future success of children. There is some evidence that iron supplementation can be useful in improving cognitive performance in iron-deficient (but non-anaemic) females, even during adolescence. However, in those with IDA, perhaps a useful way forward is to utilize both supplementation, as well as cognitive/brain training for maximum support for their learning needs.