Investigation Of Intelligence Quotient, Psychomotor Development, And Subclinical Impairment In Schoolchildren In Iodine Deficiency Areas

Iodine deficiency disorders (IDD) were a series of disorders resulted from iodine deficiency in human surroundings, including endemic goiter, endemic cretinism, and subclinical cretinism, etc. In China, Iodized salt has been supplied universally to ID areas since 1960s, and Universal Salt Iodization ( USI) was adopted in 1995 as the national strategy. In 2000, the stage goal of eliminating iodine deficiency disorders (IDD) has basically been reached, but there was still subclinical cretinism in ID areas although iodized salt has been supplied. In ID areas after the adoption of USI, the prevalence of the mild intelligence retardation and psychomotor abnormality need to be confirmed. This investigation was carried out in schoolchildren in ID areas after the adoption of USI to 1) observe the IQ and psychomotor development of the schoolchildren in ID areas after the adoption of USI, 2) evaluate the effect of the adoption of USI on the intelligence and psychomotor development of schoolchildren lived in ID areas.Methods1. All 8 - 13 yrs old children in the primary school of the selected IDD areas were investigated, and they were born and brought up in the selected IDD areas . Severe, moderate, and mild IDD areas were all selected in faku county and xinmin city.2. Intelligence quotient (IQ) was measured by combined ravens test, second edition ( CRT - C2 ). Psychomotor development, hearing, bone age, and somatic retardation were examined by Jinyi Psychomotor Test Battery (JPB) , audiometer, radiograph, and standard physical measurer, respectively.3. We used Statistical Analysis Software (SAS, vision 6. 12) to analyse the results, which were summarized by frequencies and percentages for categorical data and by mean and standard deviations for continuous data. Pearson chi -square and Kruskal - Walls test were used to test the significance of differences among proportions. Difference of means was assessed by the one - way ANOVA test, and when significant difference was found, the means were compared by the Student - Newman - Keuls multiple comparison test. Multiple linear regression models were used to assess the relation between the children & age, sex, or areas and the score of Neurointellectual test. P <0. 05 was regarded as the level of significance.Results1. The IQ scores of all subjects in the severe and moderate ID areas were 101. 92 ± 15. 64 and 99. 49 ± 16. 58 respectively, lower than those in the mild ID areas (108. 18 ± 12. 44, P <0. 01). Multiple linear regression showed that the IQ scores correlated negatively with age (P < 0. 0001) , there was an increase in IQ of 2. 07 point for each 1 -yr decrease in schoolchildrens age, after controlling for the impact of sex and the category of ID areas.2. The total T scores of all subjects in the severe and moderate ID areas were 316. 17 ±42.26 and 330.46 ±47. 66 respectively, lower than those in mild ID areas (341. 75 ±48. 11, P <0. 05). Multiple linear regression showed that the total T scores correlated negatively with age (P =0. 0006) , there was an increase in total T scores of JPB of 4. 88 point for each 1 -yr decrease in schoolchildren s age, after controlling for the impact of sex and the category of ID areas.3. Subclinical impairments prevalence in severe, moderate, and mild ID areas was 29.33% , 33.70% , and 23.42% , respectively. Subclinical impair-ments prevalence was significantly higher in severe and moderate ID areas than in mild ID areas (P <0. 05). No significant difference existed between the severe ID areas and moderate ID areas.Conclusion1. This investigation found that in shenyang city, the intelligence and psy-chomotor performance were worse in the severe or moderate ID areas than in the mild ID areas,and the subclinical impairment situation was worse in the severe or moderate ID areas than in the mild ID areas. In severe, or moderate, or mild ID areas, the psychomotor abnormal and subclinical impairment situation was severe.2. In the investigated children' s life, the earlier the children benefited from USI , the better their intelligence and psychomotor development would be.