The authors scoured the educational and medical records of all 5,357 children born in five towns in Olmsted County, Minn., between 1976 and 1982, and who had lived in the same county at least until the age of 5.
Generally, the children who had been under anesthesia had received halothane and nitrous oxide (laughing gas). Halothane is no longer available in the United States, according to the study, but it has been replaced by newer drugs, although these work by similar mechanisms. Nitrous oxide is used widely in this country.
Children's brains are still rapidly developing during these early years of life and are therefore very vulnerable to insults, the researchers noted.
The team said that just one exposure to anesthesia did not up the risk of developing a learning disability before the age of 19. Two exposures, however, increased the risk by 59 percent, while three or more exposures increased the risk by a factor of 2.6. Children who stayed under anesthesia for longer periods of time also faced a greater degree of risk.
But the association could also be due to the stress from the surgery itself or to the fact that children who undergo multiple surgeries at such a young age are sicker and therefore more likely to develop learning disabilities in general, the study suggested.
If future research does point to the anesthesia as the guilty party, new anesthesia agents may mitigate the effect.
But, Wilder pointed out, "even though finding new drugs might be the holy grail, that won't be easy."
Visit the American Society of Anesthesiologists for a history of pediatric anesthesia.
SOURCES: Robert Wilder, M.D., Ph.D., consultant, anesthesiology, Mayo Clinic, and associate professor, anesthesiology, Mayo Medical School, Rochester, Minn.; A
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