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Iron status in early infancy is associated with trajectories of cognitive development up to pre-school age in rural Gambia.

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Mason, Luke 
Milosavljevic, Bosiljka  ORCID logo
Mbye, Ebrima 
Touray, Ebou 


INTRODUCTION: Iron deficiency is among the leading risk factors for poor cognitive development. However, interventions targeting iron deficiency have had mixed results on cognitive outcomes. This may be due to previous interventions focusing on the correction of iron deficiency anaemia in late infancy and early childhood, at which point long lasting neural impacts may already be established. We hypothesise that the relationship between iron status and cognitive development will be observable in the first months of life and will not be recovered by 5 years of age. METHODS: Using data from the Brain Imaging for Global Health (BRIGHT) Study in Gambia (n = 179), we conducted mixed effects modelling to assess the relationship between iron status at 5 months of age and trajectories of cognitive development from 5 months- 5 years using (i) a standardised measure of cognitive development (Mullen Scales of Early Learning) and (ii) an eye-tracking assessment of attention processing (visual disengagement time). RESULTS: All infants were iron sufficient at 1 month of age. At 5 and 12 months of age 30% and 55% of infants were iron deficient respectively. In fully adjusted analyses, infants in the lowest tercile of soluble transferrin receptor (sTfR) (best iron status) achieved MSEL Cognitive Scores on average 1.9 points higher than infants in the highest sTfR tercile (p = 0.009, effect size = 0.48). There was no evidence that this group difference was recovered by 5 years of age. Infants in the lowest sTfR tercile had visual disengagement time 57ms faster than the highest tercile (p = 0.001, effect size = 0.59). However, this difference diminished by early childhood (p = 0.024). CONCLUSION: Infants are at risk of iron deficiency in early infancy. A relationship between iron status and cognitive development is apparent from 5 months of age and remains observable at 5 years of age. One mechanism by which iron availability in early infancy impacts brain development may be through effects on early attentional processing, which is rapidly developing and has substantial nutritional requirements during this period. To support neurocognitive development, prevention of iron deficiency in pre- and early postnatal life may be more effective than correcting iron deficiency once already established.


Acknowledgements: We would like to acknowledge the contribution of the BRIGHT Study Team (Andrew Prentice, Lena Acolatse, Saikou Drammeh, Buba Jobarteh, Mariama Saidykhan, Fabakary Njie, Tijan Fadera, Ousman Kambi, Ebrima Drammeh, Kassa Kora, Laura Steiner, Jasmine Siew). We also give special mention to Dr Momodou.K. Darboe, who was the co-investigator of the BRIGHT project in Keneba and at the Medical Research Unit, The Gambia at the London School of Hygiene and Tropical Medicine (MRCG@LSHTM). He supported the team at the local site and provided an invaluable contribution to the adaptation of measures for the local context. He died in 2021, before he was able to see the conclusion of this research project. We thank the women and infants who gave their time to this study and the wider team at MRCG@LSHTM- Keneba Field station including the clinical and laboratory staff, the data team and all those without whom the BRIGHT study would not have been possible.


BRIGHT Study Team

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PLOS Glob Public Health

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Public Library of Science (PLoS)
MRC (MR/S018425/1)