NEWS:STEROIDS USED IN PREEMIES MAY CAUSE BRAIN DAMAGE
Certain drugs used in premature babies and in pregnant women at risk for preterm deliveries kill brain cells, new animal studies show.A class of steroid drugs called glucocorticoids, which is often used to beef up the underdeveloped lungs of premature infants, irreversibly damages brain cells in the cerebellums of baby mice — the area of the brain responsible for coordination and balance.
Scientists from Washington University School of Medicine in St. Louis presented their research at this week’s Society for Neuroscience conference in Washington, D.C. They also identified a time frame during which newborn babies’ brains appear most vulnerable to the steroids. In the study, brain cells in mice died after treatments that were given four to 10 days after birth, says study author Kevin Noguchi, a postdoctoral fellow in the university’s department of psychiatry.He says that danger zone translates to human babies from about 20 weeks in the womb to six weeks after birth. Noguchi says other studies have shown that the synthetic steroid — called dexamethasone (usually used postnatally) — causes later motor and cognitive problems in children. Because of that research, in 2002, the American Academy of Pediatrics recommended that postnatal glucocorticoid use be halted, but the drugs are still used regularly in mothers at risk for early deliveries.Noguchi estimates that about 8% of infants born at a weight of 3.3 pounds or less are still given these drugs. “Thousands of babies a year receive these drugs that can cause damage to the brain,” he says.
The researchers have also studied adolescent mice that were treated with glucocorticoids during early infancy, and reported that a single exposure to the medication permanently damaged the cerebellums of the animals’ brains. Co-author Nuri Farber, an associate professor of psychiatry at Washington University, says other researchers have found dips in the IQs of children who have been given these drugs early in life.
“Our finding might explain why,” Farber says.
There are other types of glucocorticoids that appear to be less toxic and may be safer than the ones commonly used today, Farber says. But he says more research is required.The authors also note that the toxic effects of the steroid drugs they studied do not appear to affect the brains of older babies, children and adults.
“Our studies in mice suggest that once a human infant is a few months old, these drugs — which are used for other medical conditions, too — don’t appear to have this type of toxic effect,” Farber says.