Hormones and Brain Function

Hormones can influence brain function in a variety of ways.1,2 Some act indirectly by disturbing the constancy of the biochemical milieu that is so necessary for normal brain function. Others act directly on neurons influencing their electric properties or the function of synapses. Some hormones have major effects on growth and differentiation of nerve cells and synapses. The most striking example is the effect of thyroid hormone, whose deficiency in early infancy may produce cretinism. In addition, sex hormones have specific effects on development of differences in behavior between the sexes.3 Another hormone that has been suspected of being essential for normal brain development is growth hormone (GH). In this issue of the Journal (p 565), Meyer-Bahlburg and his co-workers report that GH deficiency is not associated with deficiency in specific mental abilities and that GH treatment does not seem to influence intelligence. Although there have been reports