Anaesthetics threaten baby brains

Rat study hints that surgery drugs can kill growing nerve cells.
5 February 2003

BRIAN FISKE

Babies need nerve cell activity to form connections in the brain. © GettyImages

Anaesthetics given to expectant mothers or young babies could damage infants' brains, warns a new study. The drugs kill nerve cells in newborn rats¹.

US researchers gave week-old rats a cocktail of anaesthetics that are commonly used in paediatric surgery. One day later they found 15 times more dead cells than normal in parts of the rodents' brains. As adults, the animals developed learning problems.

The study supports concerns that newborn babies could suffer subtle brain damage after surgery. "We do not want to create a panic," cautions team member John Olney of Washington University School of Medicine in St Louis, Missouri. It is too early to say whether anaesthetics have the same effect in humans, he explains.

"The public should not be unduly alarmed," agrees anaesthesia expert Neil Harrison of Cornell University in New York. Newborns have been given such drugs for years without apparent problems, he notes.

Olney suggests that doctors could reduce any potential risks by limiting the time that infants are sedated. Non-critical operations could even be delayed, he adds - the brain is less vulnerable as infants get older.

Common theme

Anaesthetics put patients to sleep by dampening the activity of nerve cells. But in a baby's growing brain, cells need this activity to form connections and thrive. "Drugs that depress the activity of a developing nerve cell can cause it to die," explains Olney.

Olney's team previously showed that alcohol kills brain cells in newborn rats; like anaesthetics, it can suppress nerve cell activity. This could partly explain why heavy drinking during pregnancy causes fetal alcohol syndrome, a leading cause of mental retardation.

Together these findings suggest that any medicine that works in the same way as alcohol and anaesthetics could be harmful to children in their first few years - including anti-epileptic drugs. The researchers plan to test other combinations of anaesthetics to find out which do most damage in rodents.

Assessing the risk in babies is more difficult, Harrison says: "It's not possible to count cell loss in a living child." Children who have undergone surgery during the first few years of life could be examined for behavioural problems as they grow up, he suggests.

Brian Fiske is an assistant editor of Nature Neuroscience.

1. Jevtovic-Todorovic, V. et al. Early exposure to common anesthetic agents causes widespread neurodegeneration in the developing rat brain and persistent learning deficits. Journal of Neuroscience, 23, 876 - 882, (2003). |Homepage|