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(203) 688-2222
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Yale-New Haven
Children's Hospital
20 York Street
New Haven, CT
06510-3202
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February 2007
News this month A recent study from Johns Hopkins University concludes that children with untreated sleep apnea perform significantly worse on IQ tests and may have brain impairments that could hinder their ability to learn new tasks. Previous studies had revealed a link between low IQ and sleep apnea in children, although this study was the first to suggest brain injury is linked to the effect. “This is truly concerning
because we saw changes
that suggests brain
injury in areas that house
critical cognitive functions,
such as attention, learning
and working memory.”
For their research, published in the August 22, 2006 issue of the online journal Public Library of Science Medicine, the Hopkins investigators compared 19 children with severe obstructive sleep apnea (OSA) — a condition associated with repeated nighttime awakenings and excessive daytime sleepiness — to 12 children without the disorder. Using a special type of magnetic resonance imaging (MRI), the researchers identified changes in two brain regions associated with higher mental function: the hippocampus and the right frontal cortex. The hippocampus, a structure in the temporal lobe, is vital to learning and memory storage, while the right frontal cortex governs higher-level thinking, such as accessing old memories and using them in new situations. Using IQ tests and other standardized performance measures of verbal performance, memory and executive function, researchers were able to link the changes in the two brain structures to deficits in neuropsychological performance. Children with OSA had lower mean IQ test scores (85) than children without OSA (101). Children with OSA also performed worse on standardized tests measuring executive functions, such as verbal working memory (8 versus 15) and word fluency (9.7 versus 12). “This is truly concerning because we saw changes that suggests brain injury in areas that house critical cognitive functions, such as attention, learning and working memory,” said Ann C. Halbower, MD, medical director of the pediatric sleep disorders program at Johns Hopkins Children’s Center and lead researcher of the study. Dr. Halbower also noted that while researchers have known that fragmented sleep, interrupted breathing and oxygen deprivation — all hallmarks of sleep apnea — harm children’s learning ability and school performance, this is the first time they have linked changes in the brain’s chemistry to the syndrome in children. “We cannot say with absolute certainty that sleep apnea caused the injury. But what we found is a very powerful association between changes in the neurons of the hippocampus and the right front cortex and IQ and other cognitive functions in which children with OSA score poorly,” said Dr. Halbower. “This should be a wake-up call to both parents and doctors that undiagnosed or untreated sleep apnea might hurt children’s brains.” In both children and adults, untreated sleep apnea has been linked to cardiovascular problems and learning and memory deficits. Obstructive sleep apnea syndrome is a relatively common problem in children, and it is increasingly recognized as a cause of daytime attention deficit and behavioral problems. “Sleep apnea is very treatable in children,” said Dr. Halbower. “If it does cause permanent impairment in brain function, then early treatment is all the more important.”
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 Pediatricians should screen patients for symptoms of obstructive sleep apnea as part of regular child examinations While researchers have known for years that obstructive sleep apnea (OSA) leads to interrupted breathing and oxygen deprivation, and negatively impacts children’s learning ability and school performance, this is the first time they have connected changes in the brain’s chemistry to OSA. The cognitive effects of untreated apnea are far more damaging in children than in adults because they occur during a critical period of brain development. The results of this study indicate that untreated OSA may impair the development of higher cognitive function in a child with obstructive sleep apnea. These preliminary findings open up a new area of investigation. It is important to discover if early detection and treatment of OSA can lead to the abnormal brain chemistry returning to normal. Based on these findings, pediatricians should screen patients for symptoms of OSA as part of regular child examinations and ensure that children who are diagnosed with OSA receive proper treatment. “The cognitive effects of
untreated apnea are far more
damaging in children than in
adults because they occur
during a critical period of
brain development.”
Parents should also be aware that one of the most important symptoms of sleep apnea is frequent obstruction in breathing that results in multiple arousals from sleep. Other symptoms include snoring, labored or loud breathing, coughing, choking, gasping, excessive nighttime sweating and, sometimes, bedwetting by children older than 6 years of age. While the prevalence of snoring in children is about 16 to 20 percent, the incidence of true obstructive sleep apnea in children is only two to three percent. But unlike the adult version, obstructive sleep apnea in children is usually unrecognized. This is usually because routine questions about sleep-disordered breathing are not asked during most office visits. Daytime signs of sleep apnea may include sleepiness, an inability to concentrate and poor performance in school. Younger children with sleep apnea may also show signs of hyperactivity and irritability. Studies have shown that a small proportion of children with attention deficit disorder may actually have OSA. If parents suspect that their child has obstructive sleep apnea, they should consult with the child’s pediatrician. The pediatrician may refer the child to a specialist in the diagnosis and treatment of pediatric sleep disorders. Although many physicians feel that a clinical diagnosis of OSA is reliable, the American Academy of Pediatrics recommends overnight polysomnography at a pediatric sleep disorders center as the best currently available test for diagnosing OSA. This test can be conducted overnight at a specialized pediatric sleep center, such as the one at Yale-New Haven Children’s Hospital. While sleeping, the child is monitored for heart rate, respiratory rate, oxygen saturation, brain activity, eye movements and body movements. Any obstruction to the child’s breathing and change in oxygen level can be easily detected. The most common treatment for children with obstructive sleep apnea is surgical removal of both the tonsils and the adenoids. In the majority of cases this is very effective in resolving symptoms. In certain cases, however, symptoms can persist, and parents and physicians should seek further consultation with a pediatric sleep specialist. A pediatric sleep disorders clinic is held twice a month at the Yale-New Haven Children’s Hospital pediatric specialty center. Appointments can be made by calling (203) 688-1240. Dr. Bhargava is an attending physician in pediatric respiratory medicine and the co-director of the Yale-New Haven Pediatric Sleep Center. Dr. Bhargava also serves as an assistant professor of the Yale School of Medicine |
