Iodine Intake and Related Cognitive Function Impairments in Elementary Schoolchildren

SIMPLE SUMMARY: This is the first survey to show throughout the application of Wechsler Intelligence Scale for Children complete form, how the adverse effects of moderate iodine-deficiency negatively impair cognitive function in schoolchildren. The results obtained suggest differences in the cognitive profile of the children with moderate iodine-deficiency, denouncing several changes in specific mental functions which could attaining their full intellectual potential, resulting in a differentiated profile of intellectual development and may have some clinical value. Working memory, in our study seriously compromised in moderate iodine-deficient schoolchildren, is used to process, and store information during complex and demanding activities and it supports many activities that iodine-deficient children usually engage in at school. Given the heavy working memory demands of classroom instructions and daily activities, it is perhaps unsurprising that one of the key characteristics of the schoolchildren with moderate iodine-deficiency is poor educational attainment, thereby; iodine deficiency represents a significant risk factor for poor educational progress. For policy makers and governments, it is imperative to act against this iodine-deficiency epidemiology in the most urgent terms. Cognitive impairments represent huge costs for the region, affecting local productivity, economy, and the region´s development and economic potential. ABSTRACT: Iodine deficiency, the most common cause of preventable mental impairment worldwide, has been linked to poorer intellectual function in several studies. However, to our knowledge, no studies have been performed in moderate iodine-deficient schoolchildren using the complete form of Wechsler Intelligence Scale for Children (WISC-III; Portuguese version). The main purpose of this study was to ascertain whether moderate iodine deficiency would affect the cognitive function of schoolchildren (7–11 years old; 3rd and 4th grades). Raven’s Colored Progressive Matrices (CPM; Portuguese version) were used for measuring the intelligence quotient (IQ) of the total population (n = 256; median UIC = 66.2 μg/L), and the WISC-III was used to study two selected subgroups: one moderately iodine-deficient (n = 30) and the other with adequate iodine intake (n = 30). WISC-III was shown to be the prime instrument for cognitive function assessment among moderate iodine-deficient schoolchildren; this subgroup had a Full-Scale IQ 15.13 points lower than the adequate iodine intake subgroup, with a magnitude effect of d = 0.7 (p = 0.013). Significant differences were also registered in 6 of the 13 Verbal-Performance IQ subtests. Moderate iodine deficiency has a substantial impact on mental development and cognitive functioning of schoolchildren, with significant impairment in both Performance IQ and Verbal IQ spectrum, adversely impacting their educational performance.