The Struggle for a Dependable Test for Alzheimer's Disease

FAITH LAPIDUS: This is SCIENCE IN THE NEWS, in VOA Special English. I’m Faith Lapidus.
BOB DOUGHTY¹: And I’m Bob Doughty. Today we tell about Alzheimer’s disease. More than a century after its discovery, Alzheimer’s disease is still destroying people’s brains. But research may offer hope for the future.
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FAITH LAPIDUS: Scientists have been attempting for years to learn who may get Alzheimer’s disease. If the condition could be identified before its worst signs appear, people might get at least temporary medical help. There is no cure for Alzheimer’s, which steals people’s ability to care for themselves. But treatment can slow its progress.
BOB DOUGHTY: The most widely held belief about the cause of Alzheimer’s is that a protein, beta-amyloid, builds up in patients’ brains. Large amounts of this protein may destroy a person’s ability to think.
A patient with dementia, right, works on a puzzle with caregivers at the Morning Glory Retirement² Home in State Line, Pennsylvania
Some scientists question whether beta-amyloid causes Alzheimer’s disease. They think that the protein build-up may result from it. But most researchers say thick tangles³ or plaques⁵ of the protein are responsible for the condition. Plaques are unusual clusters, or groups, of proteins. The researchers say beta-amyloid destroys communication links in the brain.
FAITH LAPIDUS: Among older people, Alzheimer’s is the most common form of dementia, the loss of abilities needed for normal life. Other mental conditions may seem like Alzheimer’s. Those conditions need medical treatment that is different from treatment for Alzheimer’s. A correct diagnosis⁶, or identification, is important.
The best way to diagnose the disease has been a medical examination of the brain after a person dies. Doctors say methods to test the living have presented problems, like high costs for widespread use.
BOB DOUGHTY: Public and medical demand for a better way has been strong. Scientists have been working to produce a dependable test for the disease in the living.
The United States’ Food and Drug Administration is considering one such method. The method combines an examination by positron emission⁷ tomography with a drug that lights up beta-amyloid. The PET device makes scans or images that doctors can read.
FAITH LAPIDUS: Studies have shown that the drug florbetapir can light up beta-amyloid and show it on the images. Florbetapir is a radioactive coloring agent. It connects with plaques in the brain. This makes it possible for doctors to see the plaques.
In January, an expert advisory⁸ panel of the FDA debated whether florbetapir was ready for marketing⁹. The group did not suggest that the FDA approve the drug at this time. Still, the experts said they made the judgment¹⁰ based on available information. And they asked for more information. They also set conditions for accepting florbetapir.
One condition is for the manufacturer to show evidence that florbetapir correctly identifies plaques. The other condition is that the manufacturer prepare a training program for experts in nuclear medicine. The advisory panel said the doctors reading the test need additional education to correctly identify the plaques.
BOB DOUGHTY: The Food and Drug Administration will decide next month whether to accept the panel’s suggestions. The FDA normally follows the advice of its expert advisers¹¹, but not always.
If it is approved, florbetapir would be the first agent permitted to measure plaque⁴ deposits in living patients. Still, the presence of plaques does not prove that a patient has Alzheimer’s disease. Doctors say some people with amyloid plaques in their brains do not have the condition.
FAITH LAPIDUS: An estimated thirty million people around the world have Alzheimer’s disease. In the United States alone, more than five million people suffer from this presently incurable¹² brain disorder¹³.
Alzheimer’s affects memory and personality -- those qualities that make a person an individual. At first, people with the condition forget simple things, like where they left the keys to their car. But as time passes, they forget more and more. They may forget what a key is used for.
BOB DOUGHTY: Patients forget the names of their husbands, wives or children. Then they forget who they are.
Finally, they remember almost nothing. It is as if their brains die before the other parts of the body. Victims of Alzheimer’s do die from its effects or conditions linked to it. But death may not come for many years.
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FAITH LAPIDUS: Dementia is the loss of thinking ability that is severe enough to interfere¹⁴ with daily activities. It is not a disease itself. Instead, dementia is a group of signs of some conditions and diseases.
Some kinds of dementia can be cured or corrected. This is especially true if they result from drugs, infection, sight or hearing problems, head injury, and heart or lung problems. Other kinds of dementia can be corrected by changing levels of hormones¹⁵ or vitamins in the body. However, brain cells of Alzheimer’s victims die. They cannot be replaced.
BOB DOUGHTY: Victims can become angry and violent as the ability to think and remember decreases. They sometimes shout and move with no purpose or goal. Or they may become very quiet.
Media reports tell about older adults found walking in places far from their homes. They do not know where they are or where they came from. These people often are suffering from Alzheimer’s disease.
FAITH LAPIDUS: Alzheimer’s generally develops differently in each person. Yet some early signs of the disease are common. The victims may not recognize changes in themselves. They may struggle to hide them.
Probably the most common early sign is short-term memory loss. The victim cannot remember something that happened yesterday, for example. Also, victims of the disease have increasing difficulty learning and storing new information. Slowly, thinking becomes much more difficult. The victims cannot understand a joke, or cannot cook a meal, or perform simple work.
BOB DOUGHTY: Another sign of the disease is difficulty solving simple problems. Alzheimer’s patients might not know what to do if food on a stove is burning. Also, people have trouble following directions or finding their way to places they have known all their lives.
Yet another sign is struggling to find the right words to express thoughts or understand what is being discussed. Finally, people with Alzheimer’s seem to change. Quiet people may become noisy and aggressive. They may easily become angry and lose their ability to trust others.
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FAITH LAPIDUS: Alzheimer’s disease normally affects people more than sixty-five years old. But rare cases have been discovered in people younger than fifty.
Alzheimer’s is identified in only about two percent of people who are sixty-five. But the risk increases to about twenty percent by age eighty. By eighty-five or ninety, half of all people are found to have some signs of the disease.
Alzheimer’s affects people of all races equally. Yet women are more likely to develop the disease than men. This is partly because women generally live longer than men.
BOB DOUGHTY: Patients cannot fully¹⁶ recover from Alzheimer’s. But many can be helped by medicine. That is especially true if the disease is found early.
The FDA has approved two kinds of drugs for Alzheimer’s. Most are called cholinesterase inhibitors. A doctor must order these medicines for patients. Cholinesterase inhibitors may work by protecting a chemical messenger needed for brain activities. They are meant to treat memory, thinking, language, judgment and other brain activity. Doctors order them for mild to moderate cases of the disease.
FAITH LAPIDUS: The second kind of drug has a long name. It is represented by the drug memantine. This medicine seems to work by governing the activity of a chemical involved in information processing, storage and memory. It treats patients with moderate to severe Alzheimer’s.
The Alzheimer’s Association says FDA-approved drugs are effective for half the people who take them. For those fifty percent, the drugs are effective for six to twelve months.
BOB DOUGHTY: The British writer Iris¹⁷ Murdoch died of Alzheimer's disease. She said it was a dark and terrible place. In nineteen six, a German doctor, Alois Alzheimer, told about a dementia patient whose brain was studied after death. Her brain had sticky structures and nerve cells that appeared to be mixed together. Now, more than one hundred years later, scientists are still trying to find the causes and treatment of Alzheimer's disease.
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FAITH LAPIDUS: This SCIENCE IN THE NEWS was written by Jerilyn Watson. I’m Faith Lapidus.
BOB DOUGHTY: And I’m Bob Doughty. Join us again next week for another SCIENCE IN THE NEWS in VOA Special English.

1 doughty   

adj.勇猛的，坚强的

参考例句：

• Most of successful men have the characteristics of contumacy and doughty.绝大多数成功人士都有共同的特质：脾气倔强，性格刚强。
• The doughty old man battled his illness with fierce determination.坚强的老人用巨大毅力与疾病作斗争。

2 retirement   

n.退休，退职

参考例句：

• She wanted to enjoy her retirement without being beset by financial worries.她想享受退休生活而不必为金钱担忧。
• I have to put everything away for my retirement.我必须把一切都积蓄起来以便退休后用。

3 tangles   

（使）缠结， （使）乱作一团( tangle的第三人称单数 )

参考例句：

• Long hair tangles easily. 长头发容易打结。
• Tangles like this still interrupted their intercourse. 像这类纠缠不清的误会仍然妨碍着他们的交情。

4 plaque   

n.饰板，匾，(医)血小板

参考例句：

• There is a commemorative plaque to the artist in the village hall.村公所里有一块纪念该艺术家的牌匾。
• Some Latin words were engraved on the plaque. 牌匾上刻着些拉丁文。

5 plaques   

（纪念性的）匾牌( plaque的名词复数 )； 纪念匾； 牙斑； 空斑

参考例句：

• Primary plaques were detectable in 16 to 20 hours. 在16到20小时内可查出原发溶斑。
• The gondoliers wore green and white livery and silver plaques on their chests. 船夫们穿着白绿两色的制服，胸前别着银质徽章。

6 diagnosis   

n.诊断，诊断结果，调查分析，判断

参考例句：

• His symptoms gave no obvious pointer to a possible diagnosis.他的症状无法作出明确的诊断。
• The engineer made a complete diagnosis of the bridge's collapse.工程师对桥的倒塌做一次彻底的调查分析。

7 emission   

n.发出物，散发物；发出，散发

参考例句：

• Rigorous measures will be taken to reduce the total pollutant emission.采取严格有力措施，降低污染物排放总量。
• Finally,the way to effectively control particulate emission is pointed out.最后，指出有效降低颗粒排放的方向。

8 advisory   

adj.劝告的，忠告的，顾问的，提供咨询

参考例句：

• I have worked in an advisory capacity with many hospitals.我曾在多家医院做过顾问工作。
• He was appointed to the advisory committee last month.他上个月获任命为顾问委员会委员。

9 marketing   

n.行销，在市场的买卖，买东西

参考例句：

• They are developing marketing network.他们正在发展销售网络。
• He often goes marketing.他经常去市场做生意。

10 judgment   

n.审判；判断力，识别力，看法，意见

参考例句：

• The chairman flatters himself on his judgment of people.主席自认为他审视人比别人高明。
• He's a man of excellent judgment.他眼力过人。

11 advisers   

顾问，劝告者( adviser的名词复数 )； （指导大学新生学科问题等的）指导教授

参考例句：

• a member of the President's favoured circle of advisers 总统宠爱的顾问班子中的一员
• She withdrew to confer with her advisers before announcing a decision. 她先去请教顾问然后再宣布决定。

12 incurable   

adj.不能医治的，不能矫正的，无救的；n.不治的病人，无救的人

参考例句：

• All three babies were born with an incurable heart condition.三个婴儿都有不可治瘉的先天性心脏病。
• He has an incurable and widespread nepotism.他们有不可救药的，到处蔓延的裙带主义。

13 disorder   

n.紊乱，混乱；骚动，骚乱；疾病，失调

参考例句：

• When returning back,he discovered the room to be in disorder.回家后，他发现屋子里乱七八糟。
• It contained a vast number of letters in great disorder.里面七零八落地装着许多信件。

14 interfere   

v.(in)干涉，干预；(with)妨碍，打扰

参考例句：

• If we interfere, it may do more harm than good.如果我们干预的话，可能弊多利少。
• When others interfere in the affair,it always makes troubles. 别人一卷入这一事件，棘手的事情就来了。

15 hormones   

n. 荷尔蒙，激素 名词hormone的复数形式

参考例句：

• This hormone interacts closely with other hormones in the body. 这种荷尔蒙与体內其他荷尔蒙紧密地相互作用。
• The adrenals produce a large per cent of a man's sex hormones. 肾上腺分泌人体的大部分性激素。

16 fully   

adv.完全地，全部地，彻底地；充分地

参考例句：

• The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气，然后全部呼出。
• They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。

17 iris   

n.虹膜，彩虹

参考例句：

• The opening of the iris is called the pupil.虹膜的开口处叫做瞳孔。
• This incredible human eye,complete with retina and iris,can be found in the Maldives.又是在马尔代夫，有这样一只难以置信的眼睛，连视网膜和虹膜都刻画齐全了。