These children also had lower IQ scores and they scored lower on standardized learning tests than children without the sleep disorder.
It is not clear if the injury is permanent or reversible with treatment for sleep apnea, but one of the study's researchers tells WebMD that there is an urgent need for additional research to find out.
"Sleep apnea is very treatable in children," pediatric lung specialist Ann C. Halbower, MD, says. "If it does cause permanent impairment in [brain] function that makes early treatment all the more important."
Sleep apnea is less common in children than in adults, but it is estimated that 2% of kids in the U.S. have some form of obstructed breathing during sleep. Enlarged tonsils and adenoids is the most common cause of sleep apnea in children, but obesityand chronic allergiescan also be a cause.
Functional brain imaging studies in adults with sleep apnea have identified abnormalities in three key regions of the brain associated with learning and memory -- the frontal cortex, the cerebellum, and the hippocampus. Although studies have also linked sleep apnea in children with memory problems, lowered intelligence, and other behavioral issues, it has not been clear if they experience the same brain changes as adults do.
In an effort to answer this question, Halbower and colleagues from Johns Hopkins University School of Medicine in Baltimore conducted specialized brain imaging studies on children with severe sleep apnea and on children without the disorder. They also conducted IQ tests and performed other standardized tests designed to measure verbal performance, memory, and learning skills.
The average IQ score among the children with sleep apnea was in the low-normal range and was 16 points lower than children without the sleep breathing disorder (85 vs. 101). Children with sleep apnea also scored consistently lower on the other performance tests.
The brain imaging studies in the children with sleep apnea showed decreased activity in regions similar to those shown in adult studies.