(PTFS03-05-26) Associations of Anemia and Iron Status on Early Learning and Memory: Evidence From Eye-Tracking Assessments

Objectives: Anemia and iron deficiency (ID) remain prevalent among young children and may influence specific domains of cognition. We examined the associations of anemia and iron status with visual attention, memory, and social engagement measured using eye-tracking assessments.

Methods: We analyzed cohort data from a randomized trial of children aged 6–9 months in rural areas of Mangochi District, Malawi (n=660) who received one egg/day or no egg for six months; the parent trial found no effects on anemia, iron status, or development. In a subgroup (n=406), anemia and iron status biomarkers were measured at baseline as continuous exposures, including hemoglobin, plasma ferritin, soluble transferrin receptor (sTfR), and body iron index (BII). Children were categorized as anemia (hemoglobin < 10.5 g/dL), ID (ferritin < 12 μg/dL, sTfR > 8.3 mg/L, or BII < 0 mg/kg), and iron deficiency anemia (IDA) for binary exposures. Six months later (12–15 months), cognitive outcomes were assessed using eye-tracking tasks. The Infant Orienting with Attention task measured attention (reaction time, task error); the Visual Paired Comparison task assessed memory (peak look duration, shift rate, novelty preference) and social engagement (eye-mouth index, eye and mouth percent dwell times). Associations were evaluated using minimally and fully adjusted regressions, and causal inference inverse probability weighting (IPW) for binary exposures. Propensity models included child, household, and parental covariates; Walker trimming addressed extreme weights in IPW estimators.

Results: Anemia was found in 45.6%, ID in 84.2%, and IDA in 41%. Only sTfR was associated with both attention and memory; a doubling of sTfR increased reaction time by 14.1 ms (95% CI: 1.1, 27.1; p=0.033) and peak look duration during learning by 11.8% (95% CI: 3.4%, 18.8%; p=0.006). Ferritin and BII were associated only with memory (via shift rate), with small effects. No associations were observed for social engagement. Anemia, ID, and IDA status were not associated with any outcomes in regression and IPW models.

Conclusions: Iron status biomarkers may be more sensitive indicators of early cognitive performance than hemoglobin alone, with memory outcomes appearing more sensitive to iron status variation.

Funding Sources: Bill & Melinda Gates Foundation, Indonesia Endowment Fund for Education