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ORIGINAL RESEARCH COMMUNICATION |
1 From the Laboratory for Human Nutrition, Swiss Federal Institute of Technology Zürich, Zürich, Switzerland (MBZ and FR); the Department of Psychology, University of Sheffield, Sheffield, United Kingdom (KC); the Ministry of Health, Tirana, Albania (MB); Child Advocacy International, Newcastle under Lyme, United Kingdom (JB); and the Department of Pediatrics, University Hospital, Tirana, Albania (LG).
Background: Iodine is required for the production of thyroid hormones, which are necessary for normal brain development and cognition. Although several randomized trials examined the effect of iodine supplementation on cognitive performance in schoolchildren, the results were equivocal.
Objective: We aimed to ascertain whether providing iodized oil to iodine-deficient children would affect their cognitive and motor performance.
Design: In a double-blind intervention trial, 10–12-y-old children (n = 310) in primary schools in rural southeastern Albania were randomly assigned to receive 400 mg I (as oral iodized oil) or placebo. We measured urinary iodine (UI), thyroid-stimulating hormone (TSH), and total thyroxine (TT4) concentrations and thyroid gland volume (by ultrasound). The children were given a battery of 7 cognitive and motor tests, which included measures of information processing, working memory, visual problem solving, visual search, and fine motor skills. Thyroid ultrasound and the biochemical and psychological tests were repeated after 24 wk.
Results: At baseline, the children's median UI concentration was 43 µg/L; 87% were goitrous, and nearly one-third had low concentrations of circulating TT4. Treatment with iodine markedly improved iodine and thyroid status: at 24 wk, median UI in the treated group was 172 µg/L, mean TT4 was 
40% higher, and the prevalence of hypothyroxinemia was < 1%. In the placebo group after the intervention, these variables did not differ significantly from baseline. Compared with placebo, iodine treatment significantly improved performance on 4 of 7 tests: rapid target marking, symbol search, rapid object naming, and Raven's Coloured Progressive Matrices (P < 0.0001).
Conclusion: Information processing, fine motor skills, and visual problem solving are improved by iodine repletion in moderately iodine-deficient schoolchildren.
Key Words: Iodine • deficiency • Albania • children • cognition • goiter • iodized oil
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