Effects of iron supplementation and anthelmintic treatment on motor and language development of preschool children in Zanzibar: double blind, placebo controlled study

Abstract

Objective: To measure the effects of iron supplementation and anthelmintic treatment on iron status, anaemia, growth, morbidity, and development of children aged 6–59 months. Design: Double blind, placebo controlled randomised factorial trial of iron supplementation and anthelmintic treatment. Setting: Community in Pemba Island, Zanzibar. Participants: 614 preschool children aged 6–59 months. Main outcome measures: Development of language and motor skills assessed by parental interview before and after treatment in age appropriate subgroups. Results: Before intervention, anaemia was prevalent and severe, and geohelminth infections were prevalent and light—Plasmodium falciparum infection was nearly universal. Iron supplementation significantly improved iron status, but not haemoglobin status. Iron supplementation improved language development by 0.8 (95% confidence interval 0.2 to 1.4) points on the 20 point scale. Iron supplementation also improved motor development, but this effect was modified by baseline haemoglobin concentrations (P=0.015 for interaction term) and was apparent only in children with baseline haemoglobin concentrations Ascaris lumbricoides and Trichuris trichiura, but not by hookworms. Mebendazole increased development scores by 0.4 (−0.3 to 1.1) points on the motor scale and 0.3 (−0.3 to 0.9) points on the language scale. Conclusions: Iron supplementation improved motor and language development of preschool children in rural Africa. The effects of iron on motor development were limited to children with more severe anaemia (baseline haemoglobin concentration What is already known on this topic Iron is needed for development and functioning of the human brain Anaemic children show developmental delays, but it is not yet clear whether iron deficiency causes these deficits or whether iron supplementation can reverse them Helminth infections in schoolchildren are associated with cognitive deficits, but few studies have been made of helminth infection and early child development What this study adds Low doses of oral iron supplementation given daily improved language development in children aged 1–4 years in Zanzibar Iron supplementation improved motor development, but only in children with initial haemoglobin concentrations below 90 g/l The effects of routine anthelmintic treatment on motor and language milestones were positive, but non-significant, with our sample size