ATLANTA – Cognitive deficits in children treated for sleep-disordered breathing may not be totally reversible, Jane F. Gaultney, Ph.D., of the University of North Carolina-Charlotte, and her associates reported in a poster session at a meeting of the Society for Research in Child Development.
Fragmented sleep may impair cognition in children even more than in adults because children are experiencing rapid neurobehavioral development, they said.
In a study of 41 children seen by a pediatric sleep physician, overnight polysomnograms were done and medical histories were taken. Twenty-seven children were diagnosed with sleep-disordered breathing and 14 with sleep-disordered breathing and periodic limb movement. Most were treated with adenotonsillectomy.
The children also were given a battery of psychological tests, including one that estimates verbal IQ, on Saturday mornings at the pediatrician's office, and were retested several months later, after parents reported that their sleep disorder seemed to have resolved.
Verbal IQ was negatively associated with measures of episodes of apnea and hypopnea (events in which breathing is restricted but does not stop completely). It also was negatively associated with the number of awakenings associated with those events and with minimal oxygen saturation during periods of REM sleep, although not with non-REM sleep periods.
The number of arousals associated with apnea or hypopnea significantly explained IQ variance beyond what was explained by minimal oxygen saturation level or the apnea/hypopnea index. This finding raises the question of whether it is the poor gas exchange associated with sleep-disordered breathing or the fragmented sleep patterns as indicated by arousals, which best explain decreased IQ scores, Dr. Gaultney and her associates said.
Apnea and hypopnea indices were obtained by averaging the number of events per hour over total sleep times recorded. A regression analysis was done, and the result was found to be significant. In the 15 children for whom data were obtained before and after treatment, cognition scores did improve, but the improvement was not statistically significant. This suggests that the deficits in cognition were not reversed.