VOA标准英语2011--Steroids Affect Brain Development in Premature Babies

Steroids Affect Brain Development in Premature¹ Babies

Premature babies routinely get powerful steroids both before and after they are born. The drugs help the babies' tiny lungs mature and boost blood pressure, among other benefits. Previous research in animals found the drugs can affect brain development. Now, a new study confirms similar effects in human babies.

Caring for premature babies requires a careful balancing act. On the one hand, preemies are at risk for a variety of medical problems. But their tiny, developing bodies are ultra sensitive to side effects from important medicines they may need.

Researcher Emily Tam, MD, of the University of California-San Francisco explains that animal studies found that the steroids called glucocorticoids affect a certain part of the brain.

"The cerebellum is particularly targeted, resulting in cell death and decreased cell growth," Tam says. "And so, the question then is, is this same thing happening in humans?"

The cerebellum is involved in motor control and some cognitive² functions, among other things, so it plays a critical role in an infant's first years.

Steroids impact the brains of infants who receive them shortly after birth.

In a study, which was published in Science Translational Medicine, 172 premature babies born in the United States and Canada got MRI scans to measure their cerebellums. Tam says researchers found no adverse³ affects from steroids given to the pregnant mothers before birth.

"On the other hand," Tam says, "we did find that when hydrocortisone and dexamethasone were given after the child was born, this was associated with decreased growth of cerebellum. So by term age, the cerebellum was 10 percent smaller that it should have been."

The findings present doctors with a real quandary⁴. The steroids are given because they help preemies’ breathing and blood circulation, which are obviously important. But the reduced cerebellum size was seen even in babies given very small doses of the glucocorticoids.

"Low doses of these drugs are not without risks. And when considering the different drug options, they should look at other options first."

Tam says her team plans to continue the study of these premature babies to see if those with smaller cerebellums are more likely to have any developmental issues as they grow up.

1 premature   

adj.比预期时间早的；不成熟的，仓促的

参考例句：

• It is yet premature to predict the possible outcome of the dialogue.预言这次对话可能有什么结果为时尚早。
• The premature baby is doing well.那个早产的婴儿很健康。

2 cognitive   

adj.认知的，认识的，有感知的

参考例句：

• As children grow older,their cognitive processes become sharper.孩子们越长越大，他们的认知过程变得更为敏锐。
• The cognitive psychologist is like the tinker who wants to know how a clock works.认知心理学者倒很像一个需要通晓钟表如何运转的钟表修理匠。

3 adverse   

adj.不利的；有害的；敌对的，不友好的

参考例句：

• He is adverse to going abroad.他反对出国。
• The improper use of medicine could lead to severe adverse reactions.用药不当会产生严重的不良反应。

4 quandary   

n.困惑，进迟两难之境

参考例句：

• I was in a quandary about whether to go.我当时正犹豫到底去不去。
• I was put in a great quandary.我陷于进退两难的窘境。