MONDAY, Nov. 17, 2008 (HealthDay News) -- Glucocorticoid drugs used to treat chronic lung damage in premature infants caused brain injury in mice and may cause cognitive and motor control problems even when they're given before birth, according to researchers at Washington University School of Medicine in St. Louis.
They examined the effects of the synthetic glucocorticoids dexamethasone and betamethasone, which are given to premature babies to aid lung development. The drugs caused brain cell death when given to mice four and 10 days after birth. The damage occurred in the cerebellum, the brain structure that controls movement and other functions.
"The cells that are damaged are called neural progenitor cells, which are responsible for producing new neurons. So you can imagine that if you kill the cells responsible for producing new neurons, you can cause severe neurodevelopmental effects," study first author Kevin K. Noguchi, a scientist in the department of psychiatry, said in a university news release.
That's what Noguchi and colleagues found when they examined adolescent mice that were given glucocorticoids during infancy. A single exposure to glucocorticoids permanently decreased the number of neurons in the cerebellum.
"The cerebellum connects to other brain structures, so when granule cells in the cerebellum are lost, you also have detrimental effects on cognitive function in non-motor regions of the brain. Other researchers have found IQ declines in children who have received these drugs early in life, and our findings may help explain why," senior investigator Dr. Nuri B. Farber, an associate professor of psychiatry, said in the news release.
If synthetic glucocorticoid drugs can be replaced with hormones made naturally in the body, it may be possible to avoid damage to brain cells while still promoting development of lungs in premature babies, the researchers said.
The study was expected to be presented Monday at the Society for Neuroscience annual meeting, in Washington, D.C.
In 2002, the American Academy of Pediatrics recommended a halt to post-natal glucocorticoid use unless used in clinical trials. However, it's still common practice to give the drugs to women at risk for preterm birth.
The Nemours Foundation has more about premature babies.