New light on link between snoring and cognitive deficits in children

About two-thirds of children with sleep-disordered breathing (SDB)— snoring or obstructive sleep apnea (OSA)— have some degree of cognitive deficit, but the severity of the cognitive deficit has been notoriously difficult to correlate to the severity of the SDB, suggesting that other important issues may be at play, or that the right factors were simply not being measured.

A new study that will be published in the first issue for November of the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine opens the door to understanding the complex relationship between sleep, breathing and brain function in a whole new way.

"A history of snoring is a predictor for cognitive deficit in children with SDB," said principle investigator Raouf Amin, M.D., professor of pediatrics and the director of the Division of Pulmonary Medicine at Cincinnati Children's Hospital Medical Center. "However, the frequency of apnea events during sleep does not predict cognitive deficit and does not correlate with the degree of cognitive deficit. Such a paradox raised the question of whether there are some variables that we do not traditionally measure in the sleep laboratory that might modify the effect of SDB on cognition."

Dr. Amin and colleagues measured a new parameter to determine whether it could explain the variability in cognitive dysfunction better than the severity of SDB: the degree to which the brain's blood remains oxygenated during sleep. Using a technology called near infrared spectroscopy, which is able to penetrate the skull with high-powered light beams to assess oxygen saturation, they measured the "regional cerebral oxygen concentration" (SrO2) in children 7 to 13 years old with SDB to varying degrees. They also measured blood pressure (BP) during sleep.