Improvement of universal salt iodization program on the intelligence quotient among children in Linxia Hui Autonomous Prefecture of Gansu

Abstract

To assess the improvement of intelligence quotient through an Universal Salt Iodization Supply Program, among children. 3518 and 1611 children were selected from primary schools in Linxia Hui Autonomous Prefecture of Gansu in 2006 and 2010 respectively. Intelligence quotient (IQ) were measured by the revised Chinese Combined Raven Test-C2 (CRT-C2). In 2006, the average IQ of children aged 8-10 was 85.1, including 16.7% of them with IQ ≤ 69. The average IQ was between 80-90 in different counties and cities, with significant differences (P < 0.05). The average IQs were 92.0, 90.6 and 81.8 among 8, 9 and 10 years old children respectively with 10 year old's low than those 8 and 9 year olds (P < 0.05). The average IQs of boys and girls were 84.5 and 85.6, but with no significant difference (P > 0.05). The average IQ of children aged 8-10 in 2010 was 97.2 and 12 points higher than in 2006 (P < 0.05), but 8 IQ points (P < 0.05) less than the average level 105 from the overall of Gansu province. 4.7% of the children having an IQ ≤ 69. IQ of children from Linxia city and Yongjing county, were up to the theoretical level of 100, with an average IQ at around 95 in other counties. The average IQs between counties or cities showed significant differences. The IQ of 8, 9 year olds and 10 year olds did not present significant difference (P > 0.05), but in boys (98.8) and in girls (95.9) the difference was significant (P < 0.05). The average IQ was close to the theoretical level (100) with the gradual implementation of universal salt iodization program, showing that the iodized salt did play a key role on children's intelligence. However, the average IQ was still lower than the average level of the whole Gansu province in 2010.