Associations between physical growth and general cognitive functioning in international adoptees from Eastern Europe at 30 months post-arrival

J Neurodev Disord. 2015;7:36. doi: 10.1186/s11689-015-9132-7. Epub 2015 Nov 15.

Abstract

Background: Internationally adopted children have often experienced early adversity and growth suppression as a consequence of institutional care. Furthermore, these children are at risk for impaired cognitive development due to their early adverse experiences. This study examined the association between physical growth, the growth hormone (GH) system, and general cognitive functioning post-adoption. Based on previous research, we expected to find that a child's initial physical growth status and normalization of the growth hormone-insulin-like growth factor 1 (GH-IGF-1) axis would be positive predictors of general cognitive functioning.

Methods: Post-institutionalized children (n = 46) adopted from Eastern Europe were seen approximately 1 month after their arrival into the USA to determine baseline measurements. They were seen again 6 and 30 months later for two follow-up sessions. Measures included anthropometry, insulin-like growth factor-1 (IGF-1), IGF binding protein-3 (IGFBP-3), Mullen Scales of Early Learning, and Stanford-Binet Intelligence Scales. Information about parental education was also collected.

Results: We found that a child's general cognitive functioning at 30 months post-adoption was predicted by their general developmental scores at 6 months post-adoption, their initial height status, and markers of the growth hormone system. Children with lower initial IGFBP-3 standard deviation (SD) scores had higher verbal IQ scores at 30 months. Furthermore, a child's initial height was found to be a significant positive predictor of non-verbal IQ.

Conclusions: These results suggest an association between a child's suppressed physical growth in response to early adversity and alterations in GH system functioning and subsequent recovery in cognitive functioning.

Keywords: Cognitive functioning; Early adversity; Growth hormone system; International adoption; Physical growth.