49 According to the passage, which of the following is NOT the reason for people’s abusing stimulants?
(A)To get high.
(B)To get medical treatment.
(C)To improve brain function
(D)To improve performance at school.

Healthy people are increasingly turning to brain-enhancing drugs like 利他能(Ritalin) for treating narcolepsy又名猝睡症、渴睡症 to boost改善；提高；增強 their performance in school or at work, researchers said.

And while some expressed表露, 陳述 alarm over the trend趨勢，趨向, others embraced the idea, provided the drugs are proven證明 safe.

“In the United States, stimulant刺激物；激勵物 medication藥物，藥劑 are widely abused,” said Dr. Nora Volkow, director of the National Institute of Drug Abuse.

“They are abused for a variety of reasons, including the fact that people want to get high, but there is the realization that they are being increasingly utilized利用（utilize的過去分詞） to improve cognitive感知的；認知 performance做, 工作情況、表現” she said.

“This is not something that is going away離開、（通常指為了度假）離家外出、消失 ” Volkow said, adding that researchers must study the long-term effects these drugs might have in healthy people.

Her concern follows a commentary評論，解說 in the journal Nature that argues for use of the drugs in healthy adults as a  legitimate合法的，正當的 way of improving brain power, much like education, the Internet, or other helpful tools.

“We should welcome new methods of improving our brain function,” Henry Greely of Stanford Law School in California, Barbara Sahakian, a psychiatry professor from the University of Cambridge in Britain and others wrote.

They cited舉例, 舉例，引證 a recent survey that found nearly 7 percent of students in U.S. universities have used prescription藥物, 處方，藥方 stimulants, and on some campuses, as many as a quarter of students have used the drugs for non-therapeutic治療的；有療效 purposes.

The researchers called for doctors, educators, regulators, and others to evaluate評估，評價 the risks and develop policies governing the use of cognitive認知的；認識力 enhancing drugs.

Volkow said she and other experts would discuss the issue at the meeting of American College of neuropsychopharmacology神經精神藥理學 in Nashville, Tennessee.