High levels of growth hormone during early infancy could partly explain the well documented cognitive difficulties pre-term children have at early school age, Australian researchers say.

Published in the Journal of Endocrinology and Metabolism the study of 83 infants born at less than 30 weeks gestation found that higher growth hormone (GH) levels in the first six weeks of life were related to poorer working memory, spatial learning and memory at age 7 years.

Higher GH levels were also associated with larger amygdala volumes, a finding which the authors said was interesting and unexpected given that there has been little mention of GH receptors located in the amygdala specifically.

There was a possibility that a window of vulnerability exists for GH whereby deficient or excessive levels may contribute to poorer cognitive outcomes in childhood, the study authors led by Peter Anderson, from the Murdoch Childrens Research Institute in Victoria said.