Improved iodine status is associated with improved mental performance of schoolchildren in Benin.

Background: An adequate iodine supply in utero and shortly after birth is known to be crucial to an individual's physical and mental development. The question of whether iodine supplementation later in life can exert a favorable influence on the mental performance of iodine-deficient populations was addressed in various studies, but with contradictory results. Objective: The aim of this study was to examine the effect of an improvement in iodine status on mental and psychomotor performance of schoolchildren (7-11 y) who were moderately to severely iodine deficient. Design: The study, which was originally planned as a double-blind, randomized, placebo-controlled intervention, was carried out in an iodine-deficient population of schoolchildren (n = 196) in northern Benin. As the population began to have access to iodized salt during the 1-y intervention period, the study population was split post hoc - on the basis of urinary iodine concentrations - into a group with improved iodine status and a group with unchanged iodine status. Changes in mental and psychomotor performance over the intervention period were compared. Results: Children with increased urinary iodine concentrations had a significantly greater increase in performance on the combination of mental tests than did the group with no change in urinary iodine concentrations. Conclusions: An improvement in iodine status, rather than iodine status itself, determined mental performance in this population, which was initially iodine deficient. These findings suggest a 'catch-up' effect in terms of mental performance

Maternal hormonal milieu influence on fetal brain development

An adverse maternal hormonal environment during pregnancy can be associated with abnormal brain growth. Subtle changes in fetal brain development have been observed even for maternal hormone levels within the currently accepted physiologic ranges. In this review, we provide an update of the research data on maternal hormonal impact on fetal neurodevelopment, giving particular emphasis to thyroid hormones and glucocorticoids. Thyroid hormones are required for normal brain development. Despite serum TSH appearing to be the most accurate indicator of thyroid function in pregnancy, maternal serum free T4 levels in the first trimester of pregnancy are the major determinant of postnatal psychomotor development. Even a transient period of maternal hypothyroxinemia at the beginning of neurogenesis can confer a higher risk of expressive language and nonverbal cognitive delays in offspring. Nevertheless, most recent clinical guidelines advocate for targeted high-risk case finding during first trimester of pregnancy despite universal thyroid function screening. Corticosteroids are determinant in suppressing cell proliferation and stimulating terminal differentiation, a fundamental switch for the maturation of fetal organs. Not surprisingly, intrauterine exposure to stress or high levels of glucocorticoids, endogenous or synthetic, has a molecular and structural impact on brain development and appears to impair cognition and increase anxiety and reactivity to stress. Limbic regions, such as hippocampus and amygdala, are particularly sensitive. Repeated doses of prenatal corticosteroids seem to have short-term benefits of less respiratory distress and fewer serious health problems in offspring. Nevertheless, neurodevelopmental growth in later childhood and adulthood needs further clarification. Future studies should address the relevance of monitoring the level of thyroid hormones and corticosteroids during pregnancy in the risk stratification for impaired postnatal neurodevelopment.This work was supported by the grant "Doutoramento em Medicina Jose de Mello Saude 2014" by Jose de Mello Saude to AM

Subclinical prenatal iodine deficiency negatively affects infant development in Northern China

Although mild-to-moderate levels of iodine deficiency (ID) have been associated with poor cognitive outcomes in children, little is known about subclinical prenatal ID and infant development. In this study, the association between elevated cord blood thyroid stimulating hormone (TSH, thyrotropin) and infant development was examined in Northern China. Three groups of infants with elevated cord blood TSH were compared with infants with normal TSH levels on an information processing task at 7 mo, and in cognitive and motor developmental assessments at 13 mo. Infants with elevated TSH had poorer information processing skills and lower scores on the cognitive development index. There were no differences in motor abilities. Relationships between socioenvironmental factors and iodine status were assessed. Infants from more rural settings and those whose mothers had completed fewer years of schooling and had lower paying occupations had higher cord blood TSH levels. A regression analysis indicated that maternal education was predictive of cognitive performance among infants with elevated TSH but not control infants. The findings suggest that subclinical prenatal ID has negative effects on infant development and that, in some instances, maternal education may ameliorate these effects

Novel DICER1 mutation as cause of multinodular goiter in children

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/101809/1/hed23250.pd