Iodine deficiency impairs intellectual and neuromotor development in apparently-normal persons. A study of rural inhabitants of north-central China

S. C. Boyages, J. K. Collins, G. F. Maberly, J. J. Jupp, J. Morris, C. J. Eastman

Research output: Contribution to journalArticlepeer-review

66 Citations (Scopus)


Intelligence was measured by means of the Hiskey-Nebraska Test of Learning Aptitude to the Griffiths Mental Development Scales in a sample of 369 patients from iodine-deficient rural villages (Baihuyao), iodine-sufficient rural villages (Huanglo) and urban populations to test for the damaging effects of iodine deficiency on the development of the nervous system in the presumed healthy section of a community. In urban school children who were aged seven to 14 years (n = 78), a normal range of measured intelligence was found (mean ± SD intelligence-quotient score, 107.0 ± 18.3). By comparison, intelligence-quotient scores were lower in all rural cohorts (a rural suppression effect) but the distribution of intelligence-quotient scores showed a further shift to the left in the iodine-deficient township. In Baihuyaon villagers who were aged 30-35 years (n = 50), who were born during the period of severe iodine deficiency, 72% of villagers had an intelligence-quotient score of less than 70 compared with 41% (P < 0.05) of villagers who were aged 28-35 years from Huanglo, a rural iodine-sufficient control group (n = 49). Although measured intelligence was higher in Baihuyaon children whose mothers had received iodized salt - 44% of seven- to 14-year-old children had intelligence-quotient scores of less than 70 (n = 141) - it remained significantly depressed compared with rural (n = 51) and urban (n = 78) control subjects (18% and 4%, respectively). These findings were consistent with other parameters (that is, the persistently-high rate of goitre), which indicated that the salt-iodization programme was inadequate. In the iodine-deficient village, lower intelligence-quotient scores showed a relationship with the detection by audiometry of nerve deafness and with the presence of abnormal neurological signs. The latter included spasticity and pyramidal signs which were of a similar pattern to the neurological deficits that have been demonstrated in overt neurological cretins. We conclude that iodine deficiency imposes a further suppressive effect on the intellectual performance of rural inhabitants, and results in a shift of the entire population distribution of cognitive skills to a lower level.

Original languageEnglish
Pages (from-to)676-682
Number of pages7
JournalMedical Journal of Australia
Issue number12
Publication statusPublished - 1989
Externally publishedYes


Dive into the research topics of 'Iodine deficiency impairs intellectual and neuromotor development in apparently-normal persons. A study of rural inhabitants of north-central China'. Together they form a unique fingerprint.

Cite this