Autism and baby size linked

A recent study at Yale has connected autism and accelerated infant body growth.

Katarzyna Chawarska, associate professor in Yale’s Child Study Center and director of the Yale School of Medicine Toddler Developmental Disabilities Clinic, found that baby boys who are diagnosed with autism, a neurological social disorder, tend to exhibit abnormal bodily growth. The study, published in the October issue of the Archives of General Psychiatry, marks the first time that researchers have shown that autism can directly lead to the excessive growth of an infant’s entire body.

“We found that atypical head overgrowth in autism is accompanied by a similar slope for overgrowth in height and weight,” Chawarska said.

Chawarska and colleagues from both the Yale School of Medicine and the Emory University School of Medicine analyzed the pediatric medical records of 64 male infants with autism. The researchers compared the growth and development of these children with 55 counterparts who developed as expected. The data showed that although the autistic children were normally sized at birth, by five months they were taller, by 9.5 months they had larger heads and by their first birthday they weighed more than nonautistic infants.

Although a link between autism and head growth in early infants is well-known, this is the first study that showed that autism was connected with abnormal body growth in any body region other than the head, Chawarska said. The study also shows that although the heads of autistic infants grow at a faster rate than those of average children, the growth of the head is still in proportion to the growth of the child’s body.

“The study is exciting in that it opens new perspectives for genetic and neurobiological research,” said Flora Vaccarino, a professor in the Child Study Center and professor of neurobiology at Yale.

Eric Courchesne, a neuroscience professor at the University of California at San Diego, said that the study is a gateway to a complete understanding of how autism and development are linked. The study, he said, was “of great importance.”

Although the data in the study shows that autism may lead to infantile overgrowth, not all children diagnosed with autism experience generalized overgrowth, Chawarska said, adding that not all children with early overgrowth develop autism. Chawarska said this meant that overgrowth is not a marker for autism, but an effect of the disorder.

Chawarska’s next step will be to extend the analysis of autism-linked growth to a larger sample size, she said, this time including female infants.

She said she also aims to characterize the physiological, and perhaps genetic, process by which autism causes excessive bodily growth in infants.

According to the Center for Disease Control, one in 110 children in the United States has some form of autism.

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