August 1, 1998
David Gozal, professor of pediatric pulmonology, recalls reading a physician's report published in 1889 describing the "awkwardness and stupidity" of children with enlarged tonsils. Although he wouldn't use terms this blunt, Gozal has shown that obstructive sleep apnea--a temporary obstruction of airflow in the upper airway usually due to large tonsils and adenoids--can lead to behavioral and learning problems in young children.
His research will appear in an upcoming issue of Pediatrics. "A proportion of young children who are performing poorly in school is likely to have part of their learning difficulties related to sleep deprivation and disrupted sleep due to obstructive sleep apnea," says Gozal, who is also director of Tulane's Comprehensive Sleep Disorders Center.
Obstructive sleep apnea develops in about 2 percent of children between ages 1 and 8, during the peak years of growth of lymphatic tissue in the upper airway. Large lymphatic tissues, such as tonsils and adenoids, may block the upper airway and cause sleeping children to awaken repeatedly throughout the night in order to resume breathing.
Sleep apnea studies show that children can experience 200 to 300 such arousals during one night, Gozal says. This sleep disorder can lead to a number of physical problems in children, Gozal says. Brain cells don't get enough oxygen for adequate development. Lack of oxygen also causes blood vessels in the lungs to contract and become thick, leading to hypertension.
These children use more energy to breathe through the obstructed airway and may not grow as well as other kids. Disrupted sleep can also curb growth by interfering with the release of growth hormone, which occurs during sleep. Behavioral and learning problems may also spring from this condition.
"In addition to having oxygen deprivation during the night, these children are very tired during the day," Gozal says. "When children are tired, they become aggressive and hyperactive and may have short attention spans."
To research how obstructive sleep apnea affects learning and behavior, Gozal studied 297 public-school first graders whose performance was in the lowest 10th percentile of their class rankings. Parents of these children provided information about snoring, sore throats and other symptoms associated with breathing problems during sleep.
Gozal's research team also recorded the amount of oxygen in the house while the children slept as a measurable indicator of whether children were experiencing obstructive sleep apnea. Of these students, he found 54 children, or 18 percent, had the symptoms of obstructive sleep apnea--a much greater percentage than the 2 percent estimated in the general population.
"We notified the parents and the children's physicians that these children have a problem," Gozal says.
Although the researchers counseled all parents, some chose not to receive treatment, which consists of removing the tonsils and adenoids. When their academic improvement in the second grade was measured, the children with the treatment improved their grade point average from 2.43 to 2.87. The other children showed no change in academic performance. These results are particularly important to African Americans, who have a higher risk of sleep apnea, Gozal says.
"We hope that we can develop a screening test that will permit the identification of kids at risk of sleep-disordered breathing," he says. "So far, we have very little information on what sleep-disordered breathing is doing to kids."
Gozal has just submitted a grant proposal to the National Institutes of Health to expand this study to include all children in Orleans Parish public schools, not just those with poor academic records. The proposal includes researchers from the psychology department on the uptown campus and the biostatistics and epidemiology department in the School of Public Health and Tropical Medicine.
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