Australasian Science: Australia's authority on science since 1938

Anaesthesia Impairs Intellect in Kids

By Stephen Luntz

An association has been found between anaesthesia in young children and impaired intellectual development, but it is not clear if the anaesthetics are to blame or the medical condition for which the child was treated.

Anaesthetist Dr Mary Hegarty is taking part in the Raine Study of 2868 children born in Western Australia between 1989 and 1992. She compared the results for 321 10-year-olds who had undergone general anaesthetic prior to the age of 3 years with a control group.

“Our data shows that children who underwent anaesthesia before the age of three were nearly twice as likely to develop a clinically significant language impairment and have problems with abstract reasoning,” Hegarty says. There was no detectable relationship with behaviour or motor skills.

Hegarty says that concerns were aroused by studies showing memory impairment in animals exposed to anaesthesia, particularly during periods of neurogenesis.

“There have been studies that looked at surrogate outcomes, such as school records and parental reporting, but this is the first time anyone has used direct measures,” she says. “These surrogates have appeared to show a connection with multiple exposures to anaesthesia, but this is the first time there has been evidence of an effect from a single exposure,” Hegarty adds. “I intend to extend the research seeing if there is a correlation with the number and duration of exposures.”

Hegarty says she only looked at anaesthetic procedures that took place before the age of three, as this is thought to be the peak time for brain development. She stresses that while the evidence in animals indicates that anaesthesia itself (rather than the surgery that accompanies it) may be responsible, other possibilities remain. “A quarter of the children had surgery for hearing problems, and this could certainly contribute to language impairment,” Hegarty notes. “We don’t really understand how anaesthesia works, so if this is the cause we don’t know the mechanism.”

Controlled trials are set to begin with children undergoing hernia operations, using either general or local anaesthetics, but Hegarty says it will be a while before long-term effects can be observed. In the meantime she says: “There’s probably more danger from delaying surgery where it is needed than from possible anaesthetic effects”.

The research was published in Pediatrics.