CHAPEL HILL - The largest, most comprehensive study of behavior ever done in short children has uncovered a strong link between shortness and behavioral adjustment problems, researchers at the University of North Carolina at Chapel Hill say.
Growth hormone treatments, however, not only boosted growth in children studied but in many cases also improved their conduct and relations with other people, the medical scientists found.
"These findings are important in part because of a lingering controversy over the possible psychological effects of short stature," said Dr. Brian Stabler, professor of psychiatry and pediatrics at the UNC-CH School of Medicine. "We believe this work demonstrates that all very short children need to be evaluated thoroughly by psychologists as well as by pediatricians and endocrinologists."
A report on the research appears in the September issue of the Journal of Pediatrics. Besides Stabler, authors include Drs. Louis E. Underwood, professor of pediatrics at UNC-CH, and Patricia T. Siegel and Richard R. Clopper, psychologists at Wayne State University and the State University of New York at Buffalo, respectively. More than 25 U.S. universities and medical organizations participated.
"For 30 years or more pediatric endocrinologists have been able to replace growth hormone if it was deficient in children so that the children have been able to grow to average or nearly average height," Stabler said. "However, it also has been observed that many of these children do not have a good quality of life."
Later, when they reach young adulthood, many continue to live with parents, don't get drivers' licenses, don't go to college and don't hold jobs long, he said.
"That led us to wonder if there wasn't something else going on with these short kids besides the growth problem," Stabler said.
Starting about a decade ago, researchers began planning a study of the question. They tested a national sample of 195 short children for intelligence, academic achievement, social skills and behavior problems before starting them on growth hormone therapy and examined them again annually for three years during treatment. Of the group, 109 were found to be growth hormone deficient, while 86 others, who had normal or nearly normal hormone levels, were classified as short for unknown reasons. Subjects ranged in age from 5 to 16 and averaged about 11 years.
Seventy-two growth hormone deficient subjects and 59 of the others completed therapy and testing. Scientists found that as a group, the short children had near average IQs and that neither IQ nor achievement test scores changed with treatment. About a third of those with short stature demonstrated some form of learning disability. Researchers also found a significant incidence of emotional and psychological problems associated with anxiety, depression and attention deficit, as well as lower grades in school.
Initially, short children scored worse on a measure of behavior problems than did a control group of children of average height, Stabler said. After hormone therapy, behavior scores improved for both groups of short children.
Subjects' scores also improved on measures of openness, health, anxiety-depression, attention and social and thought problems, he said. Children classified as growth hormone deficient showed slightly larger positive effects of hormone treatment than did those whose shortness was unexplained.
"There are several possible explanations for the improvements, one that growth hormone therapy boosts brain chemicals and neurotransmitters that didn't work as well as they would have if hormone secretion had been normal," Stabler said.
Behavior problems in the short children improved quickly with six months of hormone replacement therapy, he said. That could not be due to growth alone since height increases so slowly.
"Short stature or growth delay in children should not be overlooked because it can relate to significant life quality and overall functioning problems besides the obvious height difficulty," Stabler said. "The therapy, which is expensive, is definitely not simply cosmetic."
"This study is unique in that it shows in a systematic way the beneficial effects of growth hormone treatment upon the behavior of some children with short stature," said Underwood, chief of pediatric endocrinology at UNC-CH and a pioneer in growth hormone therapy. "Some specialists have argued that there is no psychological disadvantage to being short. We believe that these children sometimes have handicaps that children of normal height don't face."
Co-authors were research coordinator Catherine E. Stoppani and biostatistician Peter G. Compton, both of Genentech Inc. The National Institutes of Health and Genentech supported the research.
Other centers involved were Children's Hospital National Medical Center in Washington, D.C., the University of South Carolina, the State University of New York at Albany, Mercy Endocrine and Diabetes Center in Toledo, Ohio, Kansas University Medical Center, City of Hope National Medical Center in Duarte, Cal., Tulane University School of Medicine in New Orleans, Children's Mercy Hospital in Kansas City, the University of Michigan, Pediatric Endocrine Associates in Tulsa and St. Joseph's Hospital in Phoenix.
Others were Arkansas Children's Hospital in Little Rock, Oregon Health Sciences University Medical Center, Children's Hospital in Richmond, Children's Hospital of Buffalo, Woodinville Pediatrics in Woodinville, Wash., Children's Hospital in Phoenix, Johns Hopkins University in Baltimore, Children's Hospital of Michigan in Detroit, University of Utah Hospital in Salt Lake City, Baystate Medical Center in Springfield, Mass., the State University of New York Health Science Center in Syracuse, Springfield (Ill.) Diabetes and Endocrine Center, the University of Iowa and Riley Hospital in Indianapolis.
By David Williamson
Note: Stabler can be reached at (919) 966-3377, Underwood at 966-4435. Contact: David Williamson, (919) 962-8596, or Bret Johnson, 962-0352.
Journal
The Journal of Pediatrics