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Effects of haemoglobin and serum ferritin on cognitive function in school children
Rassamee Sungthong1, Ladda Mo-suwan, Virasakdi Chongsuvivatwong
1Epidemiology Unit, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand. sburapat@medicine.psu.ac.th
Insights
Iron deficiency impacts cognitive function in children. Cognitive function improves with higher hemoglobin levels in children with iron deficiency, showing a dose-response relationship.
Area of Science:
- Pediatric Nutrition
- Cognitive Neuroscience
- Hematology
Background:
- The relationship between iron deficiency anemia and cognitive impairment in young children is established.
- However, the distinct roles of iron deficiency versus anemia, and their interaction, on cognitive outcomes remain unclear.
Purpose of the Study:
- To investigate the independent and combined effects of iron deficiency and anemia on cognitive function and school performance in school-aged children.
- To explore the dose-response relationship between hemoglobin levels and cognitive function in children with varying iron status.
Main Methods:
- A cross-sectional study involving 427 school children from socioeconomically deprived communities in Thailand.
- Iron status assessed via hemoglobin and serum ferritin levels.
- Cognitive function measured using IQ tests and school performance scores (Thai language, mathematics) adjusted for grade and school.
Main Results:
- Children with iron deficiency anemia exhibited the lowest cognitive function scores.
- Conversely, children with non-anemic iron deficiency and adequate hemoglobin levels demonstrated significantly higher cognitive function.
- A positive dose-response relationship was observed between hemoglobin concentration and cognitive function in children with iron deficiency, but not in iron-sufficient children.
Conclusions:
- Both iron deficiency and anemia negatively impact cognitive function in children.
- Cognitive function is sensitive to hemoglobin levels, particularly in the presence of iron deficiency, suggesting a critical role for iron in cognitive development.
Abstract:
The association between iron deficiency anaemia and cognitive function impairment has been widely reported in young children, but whether the impairment is a result of iron deficiency per se or a combination of iron deficiency and anaemia, and how these conditions interact, is still questionable. Four hundred and twenty-seven school children from two schools in socioeconomically deprived communities were selected in southern Thailand. Iron status was determined by haemoglobin and serum ferritin concentrations. Cognitive function in this study was measured by IQ test and school performance, including Thai language and mathematics scores, using z-scores based on distributions within the same grade and school. Data on demography and socioeconomic status were collected by questionnaire answered by the parents. Linear regression models were used to investigate the effect of anaemia and iron deficiency, reflected by haemoglobin and serum ferritin concentration, on cognitive function and school performance. We found that cognitive function increased with increased haemoglobin concentration in children with iron deficiency, but did not change with haemoglobin concentration in children with normal serum ferritin level. Children with iron deficiency anaemia had consistently the poorest cognitive function (IQ, 74.6 points; Thai language score, 0.3 SD below average; and mathematics score, 0.5 SD below average). Children with non-anaemic iron deficiency but with high haemoglobin 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). This study found a dose-response relationship between haemoglobin and cognitive function in children with iron deficiency, whereas no similar evidence was found in iron sufficient children.