Iodine and Other Nutritional Predictors of Preschool-Aged Children's Development in Amhara, Ethiopia
Frances Aboud *
McGill University, Montreal, QC, Canada.
Grace Marquis
McGill University, Montreal, QC, Canada.
Karim Bougma
McGill University, Montreal, QC, Canada.
Tizita Lemma
Bahir Dar University, Bahir Dar, Amhara, Ethiopia.
Husein Mohammed
McGill University, Montreal, QC, Canada.
Aregash Samuel
Ethiopian Health & Nutrition Research Institute, Addis Ababa, Ethiopia.
*Author to whom correspondence should be addressed.
Abstract
Objectives: The study examined nutritional and other predictors of mental development of preschool-aged children in northern Ethiopia. The current analysis of older children from the iodized salt project (see Infant study) included the effects of iodized salt, along with other determinants.
Methods: Using a cluster randomized design, 1550 children in 60 villages in Amhara, Ethiopia were given tests of School Readiness and Wechsler verbal and nonverbal reasoning, twice at 54-60 months and again at 69-78 months. Between these assessments, iodized salt was distributed early in the markets of 30 randomly assigned villages (intervention group) before it became available in 30 control villages.
Results: The two groups were largely comparable at baseline. In addition to the effects of iodized salt on School Readiness (p=0.01) and nonverbal reasoning (p<0.10) seen at the endline, the following predictors were positively and significantly associated with cognitive outcomes: height-for-age z-score (HAZ; p<0.0001), weight-for-age z-score (p<0.0001), family assets (p<0.0001), recent deworming (p=0.01), improved water/sanitation (p<0.01), and mother's education (p<0.05). Although over two-thirds had palpable goiter, hemoglobin status was good (M=134 g/L). Children overall performed relatively better on the School Readiness test (M=6.66 Intervention and 6.25 Control) than nonverbal reasoning (M= 4.15 Intervention and 3.95 Control)(theoretic ranges 0-19). A multiple regression, following the Baron and Kenny mediation analysis, on School Readiness scores revealed that the intervention effect was partially mediated by HAZ (std β= 0.37 , p<0.0001).
Conclusions: In conclusion, iodized salt improved children's School Readiness skills and nonverbal reasoning, both directly, and indirectly by way of its effect on growth.