Growth hormone deficiency, brain development, and intelligence

Twenty-nine patients with growth hormone (GH) deficiency were selected according to the following criteria: no evidence of reversible GH deficiency, onset of growth retardation in early childhood, and no evidence of pituitary tumors or other direct pituitary trauma. Fourteen patients had evidence of multiple hormone deficiencies, 14 had isolated GH deficiency, and one patient questionable isolated GH deficiency. Psychometric testing showed a normal IQ distribution. The GH deficiency was not associated with deficiencies in specific mental abilities. Likewise, GH treatment in later childhood and adolescence did not seem to influence intelligence. Patients with multiple hormone deficiencies had somewhat lower IQs than patients with isolated GH deficiency when socioeconomic status was controlled. We conclude that GH deficiency itself does not seem to affect human brain development and intelligence.