Thyroid Hormones and Human Mental Development

Abstract

This chapter presents two different models to discuss the effect of thyroid hormones on human mental development, which are pre- and postnatal development in the presence of an inadequate supply of thyroid hormones. The first model concerns the development of techniques for recognizing congenital hypothyroidism at birth—a condition that is known to be present in 1 out of 5000 babies. The aim is to institute adequate substitution therapy, and the hope is to prevent irreversible mental retardation in these babies. The second model concerns the problem of preventing endemic goiter and cretinism in regions of severe iodine deficiency. There are similarities between congenital hypothyroidism and endemic cretinism with respect to the periods during which the development of the central nervous system is exposed to hypothyroidism, prenatally, as well as postnatally. Both conditions are subjected, for instance, to a variable degree of hypothyroidism. The fact is recalled that the people with mild congenital hypothyroidism, and treated either early or late, end up in 41% of the cases with an I. Q. of 90 or better.