Researchers from the National Institutes of Health, the Centers for Disease Control and Prevention, the Cincinnati Children’s Hospital, and the University Of Cincinnati College Of Medicine, all reported that boys with autism and autism spectrum disorder (ASD) had higher levels of growth hormones than their non-autistic peers. This may help to explain why children with autism usually have a larger head circumference than their peers, weighed more, and had a higher body mass index (BMI). Apparently, young children with autism have accelerated head growth in early life, which appears disproportionate when compared to boys without these conditions.

The following quote is from a story by Sue Herera called Autism research focuses on early intervention, Genetic clues sought to fight against disorder, February 23, 2005.

"Children with autism have an unusual pattern of head growth," said Dr. Wendy Stone, a clinical psychologist at Vanderbilt. "Their head size as measured externally accelerates, and then it levels off. The question is whether that acceleration in head size can be a marker of autism."

The following definition of autism is given in the story Boys with Autism, Related Disorders, Have High Levels of Growth Hormones in June 2007. “Autism is a complex developmental disorder that includes problems with social interaction and communication. The term autism spectrum disorder (ASD) refers to individuals who have a less severe form of autism.”

Included in the study were 130 boys of whom 71 had autism and ASD. Their height, weight, head circumference, and growth-related hormone levels, were compared to the growth and maturity of the 59 boys who did not have these conditions. The results indicated that two hormones, which directly regulate growth, were higher in the boys with autism. Apparently, human growth hormone is difficult to evaluate so researchers instead measured growth-related hormones that stimulate cellular growth. Other hormones that are related to growth, such as insulin-like growth factor binding protein and growth hormone binding protein also displayed higher levels in the boys with autism.

Researchers made it clear, that they determined that the higher growth-related hormone levels in the boys with autism were not from them weighing more or having a higher body mass index. The researches excluded children from the study who had conditions which may affect growth such as severe prematurity, long-term illness, or Fragile X syndrome. The researchers were also unable to include girls in the study, since girls are less likely to develop autism, they couldn’t recruit a sufficient number of girls.

While the boys with autism and ASD were heavier and had larger heads, their bone age was the same as the control group, ruling out the theory that boys with autism just mature faster than other boys do. Future studies may concentrate on whether higher levels of growth hormones could be directly related to the development of autism.

Related reading on Autism.
Autism Indicator?-Name Recognition
What is Institutional Autism?
What Kind of World Do You Want…Autism Speaks
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The National Institutes of Health (NIH) — The Nation's Medical Research Agency — includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. It is the primary federal agency for conducting and supporting basic, clinical and translational medical research, and it investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs,