Although this is the first human study to indicate such an association, it's still unclear if the anesthesia is the culprit, or if some other factor is at play.
"We don't want to alarm parents," said Dr. Robert Wilder, lead author of a study appearing in the April issue of Anesthesiology. "We have an association here between kids who received two or more anesthetics in surgery and an increase in learning disabilities, but we don't have clear causality that it was the anesthetics that caused the learning disabilities."
"Even if I knew for a fact that anesthesia might be increasing the risk for learning disabilities, my advice would still be, if your kid needs to have surgery done, they're better off having the anesthetic," added Wilder, who is a consultant in anesthesiology at the Mayo Clinic in Rochester, Minn., and an associate professor of anesthesiology at the Mayo Medical School. "Of course, you don't want to submit your kid to any unnecessary surgical or medical procedure, but that would have been my advice before studying this."
Prior animal studies have suggested that anesthesia drugs might affect the developing brain.
One study last year found that youngsters under the age of 3 who had hernia surgery showed almost twice the risk of behavioral or developmental problems later compared to kids who hadn't had surgery. Researchers suspect that exposure to general anesthesia during these operations might have played a role in the jump in risk.
Other studies have demonstrated a similar link. Still, the authors of this study said it's unclear if anesthesia really affects this risk in children.
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 Halothane is no longer available in the United States, according to the study, but it has been replaced by newer drugs, although these work by similar mechanisms.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."
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