title: Iodine supplementation improves cognition in iodine-deficient schoolchildren in Albania: a randomized, controlled, double-blind study.
abstract: 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.
  
  
  METHODS
  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 microg/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 microg/L, mean TT4 was approximately 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).
  
  
  CONCLUSIONS
  Information processing, fine motor skills, and visual problem solving are improved by iodine repletion in moderately iodine-deficient schoolchildren.
authors.affiliation: Laboratory for Human Nutrition, Swiss Federal Institute of Technology Zürich, Zürich, Switzerland. michael.zimmermann@ilw.agrl.ethz.ch
authors.forename: Michael B
authors.initials: MB
authors.lastname: Zimmermann
authors.forename: Kevin
authors.initials: K
authors.lastname: Connolly
authors.forename: Maksim
authors.initials: M
authors.lastname: Bozo
authors.forename: John
authors.initials: J
authors.lastname: Bridson
authors.forename: Fabian
authors.initials: F
authors.lastname: Rohner
authors.forename: Lindita
authors.initials: L
authors.lastname: Grimci
mesh_terms: D000415:Albania / Q000453:epidemiology; D002648:Child; D003071:Cognition / Q000187:drug effects*; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006042:Goiter / Q000097:blood / Q000188:drug therapy* / Q000453:epidemiology; D006801:Humans; D007455:Iodine / Q000008:administration & dosage / Q000172:deficiency* / Q000652:urine; D007459:Iodized Oil / Q000008:administration & dosage*; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D015995:Prevalence; D011594:Psychometrics; D013961:Thyroid Gland / Q000000981:diagnostic imaging*; D013963:Thyroid Hormones / Q000097:blood*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D016896:Treatment Outcome; D014463:Ultrasonography
chemical_list: D013963:Thyroid Hormones; D007459:Iodized Oil; D013972:Thyrotropin; D007455:Iodine; D013974:Thyroxine