Chronic Iron Deficiency and Cognitive Function in Early Childhood

BACKGROUND AND OBJECTIVES A landmark longitudinal study, conducted in Costa Rica in the 1980s, found that children with chronic iron deficiency compared with good iron status in infancy had 8 to 9 points lower cognitive scores, up to 19 years of age. Our objective was to examine this association in a contemporary, high-resource setting. METHODS This was a prospective observational study of children aged 12 to 40 months screened with hemoglobin and serum ferritin. All parents received diet advice; children received oral iron according to iron status. After 4 months, children were grouped as: chronic iron deficiency (iron deficiency anemia at baseline or persistent nonanemic iron deficiency) or iron sufficiency (IS) (IS at baseline or resolved nonanemic iron deficiency). Outcomes measured at 4 and 12 months included the Early Learning Composite (from the Mullen Scales of Early Learning) and serum ferritin. RESULTS Of 1478 children screened, 116 were included (41 chronic, 75 sufficient). Using multivariable analyses, the mean between-group differences in the Early Learning Composite at 4 months was −6.4 points (95% confidence interval [CI]: −12.4 to −0.3, P = .04) and at 12 months was −7.4 points (95% CI: −14.0 to −0.8, P = .03). The mean between-group differences in serum ferritin at 4 months was 14.3 μg/L (95% CI: 1.3–27.4, P = .03) and was not significantly different at 12 months. CONCLUSIONS Children with chronic iron deficiency, compared with children with IS, demonstrated improved iron status, but cognitive scores 6 to 7 points lower 4 and 12 months after intervention. Future research may examine outcomes of a screening strategy on the basis of early detection of iron deficiency using serum ferritin.