2. 医学
  3. Car keys are misplaced, a name resists moving past the tip of the tongue. Often, we respond with humor: "I must be getting Alzhe

Car keys are misplaced, a name resists moving past the tip of the tongue. Often, we respond with humor: "I must be getting Alzhe

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问题     Car keys are misplaced, a name resists moving past the tip of the tongue. Often, we respond with humor: "I must be getting Alzheimer’ s." But the memory loss that age can bring differs greatly from the dementia of Alzheimer’ s. Slowly, fatally, Alzheimer’ s erodes memory, personality and self-awareness. As many as 4 million Americans have it - one in 10 people over 65 and half of those over 85.
    It has no cure, and few effective treatments. But in the last decade scientists have started to understand the biochemistry behind Alzheimer’ s. Today at least 17 drugs are in development. "We don’t have the penicillin for Alzheimer’ s yet," says Dr. Rosenberg. "But it’ s coming." And some of what researchers learn about how this illness rots memory might even help those folks who mislaid their keys.
    Today’ s treatments only ease symptoms. One of Alzheimer’ s main effects is the destruction of brain cells that produce the neurotransmitter acetylcholine, a chemical essential to learning and memory. Neither of the drugs used most widely for Alzheimer’ s, Cognex and Aricept, slow the death of those cells. Instead, the drugs slow the deterioration by inhibiting the action of acetylcholinesterase, an enzyme that breaks acetylcholine down. "The drugs help make the best use of what you have left," says Dr. Tanzi. Yet the drugs have limitations: Cognex only works for a few patients and can cause liver problems. Aricept spares the liver, but its benefits are modest. At least three improved acetylcholinesterase inhibitors are on deck; the first could be out by fall.
    Future treatments will have to attack the disease more directly. Scientists hope to control the physical changes in the brain that cause the dementia, such as plaques made of protein called beta amyloid that gum up neurons. Amyloid is found throughout the body but has an abnormal form toxic to neurons in the brain. For reasons no one is sure of, an enzyme can divide a larger protein improperly, creating the dangerous amyloid beta. Some chemicals appear to block the cleaving enzyme; they may someday lead to new usable drugs.
According to the passage, the present treatment of Alzheimer’ s is unsatisfactory because______.
选项 A、scientists haven’t found the cause of the disease
B、the drugs used are effective only for a few patients
C、the two drugs used both have side effects
D、no effective drugs have been discovered yet to cure the disease
答案D
解析
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