Title

Accelerated head and body growth during infancy in children later diagnosed with autism spectrum disorders: A comparative study of optimal outcome children

Date of Completion

January 2008

Keywords

Psychology, Developmental|Psychology, Clinical|Psychology, Physiological

Degree

Ph.D.

Abstract

Previous research has demonstrated both accelerated head growth (Courchesne et al., 2003; Mraz et al., in press) and accelerated length and weight growth during infancy in children later diagnosed with ASD. However, earlier findings have also shown that when length and weight are controlled for, head circumference (HC) growth is no longer significantly greater than normal (Mraz et al., in press). Findings relating early HC to outcome have been inconsistent, but no study has yet examined head growth in children who move off the autism spectrum. Measurements of HC, body length, and body weight taken during the first two years of life were obtained from a sample of 24 ASD children who maintained their ASD diagnoses over time (ASD-S group), and were compared to both a sample of 15 optimal outcome ASD children who lost their diagnoses (ASD-OO) and to a local control sample of 37 typically developing children. Results from growth curve modeling showed that the rates of HC and weight growth were significantly greater in both ASD groups compared to controls, with length growth significantly greater than controls in the ASD-S group only. There were no significant differences in the rates of HC, length or weight growth between the ASD-S and ASD-OO groups. However, when length and weight were controlled for, accelerated HC growth remained significant in the ASD-OO group but not the ASD-S group. In addition, clinical scores at a child's first and second evaluation did not predict head size or rate of head growth during infancy, although there was a trend for an association between larger head size at both birth and 15 to 25 months and greater cognitive ability. These findings suggest that optimal outcome ASD children and children who maintain their diagnoses show similar HC, length and weight growth trajectories during infancy, although subtle differences in body growth may exist between groups. ^