A team based in Songkhla, Thailand, investigated the effects of hemoglobin and serum ferritin levels on cognitive function in schoolchildren.
The association between iron-deficiency anemia and cognitive function impairment has been widely reported in young children. However it is still questionable whether the impairment is a result of iron deficiency per se, or a combination of iron deficiency and anemia.
A total of 427 schoolchildren, from 2 schools in socioeconomically deprived communities, were selected in southern Thailand.
Iron status was determined by hemoglobin and serum ferritin concentrations.
Cognitive function in this study was measured by IQ test and school performance, including Thai language and mathematics scores.
| Children with iron-deficiency anemia had poorest cognitive function.
| Asia Pacific Journal of Clinical Nutrition |
In addition, data on demography and socioeconomic status were collected by questionnaire answered by the parents.
The researchers found that cognitive function increased with elevated hemoglobin concentration in children with iron deficiency. However, it did not change with hemoglobin concentration in children with normal serum ferritin level.
Children with iron-deficiency anemia consistently had the poorest cognitive function (IQ, 74.6 points; Thai language score 0.3 standard deviations (SD) below average; and mathematics score 0.5 SD below average).
On the other hand, children with non-anemic iron deficiency, but with high hemoglobin levels, had significantly high cognitive function (IQ, 86.5 points; Thai language score 0.8 SD above average; and mathematics score 1.1 SD above average).
Dr Rassamee Sungthong, of the Prince of Songkla University, concluded on behalf of the group, "This study found a dose-response relationship between hemoglobin and cognitive function in children with iron deficiency, whereas no similar evidence was found in iron sufficient children."