Iodine and other Nutritional Predictors of Infant and Young Child Development: Results from a Cluster Randomized Trial in Amhara, Ethiopia

Abstract

Objectives: The objective was to examine nutritional, health, and social predictors of early child mental development in the Amhara region of Ethiopia Methods: Using a cluster randomized design, iodized salt was forced early into the markets of 30 villages (intervention group) before it became available in the 30 control villages following national salt iodization legislation. A total of 1880 infants 6 to 10 mo old in the 60 villages were administered Bayley Scales of Infant and Toddler Development (BSID-III) at baseline and when they were 20-29 mo of age (86% of sample) Results: The two groups had similar socioeconomic, nutrition, and mental development scores at baseline. These variables were significant predictors of endline cognitive and language development scores: length-for-age z-score (p<0.001), weight-for-age z-score (p<0.001), psychosocial stimulation (p<0.001), water/sanitation (p<0.001), mother's education (p<0.01), family assets (p<0.001), recent deworming (p<0.05), and maternal depression (p<0.05). The intervention group had significantly higher mental development scores, and a multiple regression analysis revealed that the intervention effect was positively partially mediated by length-for-age z-score (std β= 0.16 to 0.21, p<0.01) and water/sanitation score (std β= 0.09 to 0.10, p<0.01). Conclusions: In conclusion, iodized salt improved children's mental development both directly and indirectly by its effect on growth. The indirect effect through water/sanitation may be because water and sanitation improve health.