Absence of growth hormone effects on cognitive function in girls with Turner syndrome

Turner syndrome (TS) is a genetic disorder characterized by short stature, gonadal dysgenesis, and a particular neurocognitive profile of normally developed language abilities (particularly verbal IQ) and impaired visual-spatial and/or visual-perceptual abilities. We have followed a large sample of girls with Turner syndrome who were enrolled in a long-term, double-blind, placebo-controlled trial of the effects of growth hormone (GH) treatment on final adult height. This study provides a unique opportunity to prospectively evaluate the effects of GH treatment on neurocognitive function in this population of girls with Turner syndrome. The GH- and placebo-treated Turner syndrome subjects were well matched for age, treatment duration, race, karyotype, and socioeconomic status. Treatment (GH or placebo) durations ranged from 1-7 yr. Whether GH deficiency and/or treatment in childhood and adolescence influences cognitive outcome in short children or GH-children is controversial. The major result of this study was the absence of GH treatment effects on cognitive function in girls with Turner syndrome. Our findings are in agreement with most of the previous studies that found no apparent growth hormone treatment effects on cognitive function in growth-hormone deficient children. We conclude that this study does not support a role for growth hormone in influencing childhood brain development in girls with Turner syndrome. Their characteristic nonverbal neurocognitive deficits were not altered with GH treatment into early adolescence.