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It is known that the brain shrinks as the body ages, but the effects on mental ability are different from person to person. Interestingly, in a study of elderly men and women, those who had more education actually had more brain shrinkage. “That may seem like bad news,” said study author Dr. Edward Coffey, a professor of psychiatry and neurology at Henry Ford Health System in Detroit. However, he explained, the finding suggests that education allows people to withstand more brain-tissue loss before their mental functioning begins to break down. The study is the first to provide biological evidence to support a concept called the “reserve” hypothesis, according to the researchers. In recent years, investigators have developed the idea that people who are more educated have greater cognitive reserves to draw upon as the brain ages; in essence, they have more brain tissue to spare.
Examining brain scans of 320 healthy men and women ages 66 to90, researchers found that for each year of education the subjects had, there was greater shrinkage of the outer layer of the brain known as the cortex. Yet on tests of cognition and memory, all participants scored in the range indicating normal. “Everyone has some degree of brain shrinkage,” Coffey said. “People lose 2.5 percent per decade starting in adulthood.” There is, however, a “remarkable range” of shrinkage among people who show no signs of mental decline, Coffey noted. Overall health, he said, accounts for some differences in brain size. Alcohol or drug use, as well as medical conditions such as diabetes and high blood pressure, contribute to brain-tissue loss throughout adulthood. In the absence of such medical conditions, Coffey said, education level helps explain the range of brain shrinkage exhibited among the mentally-fit elderly. The more-educated can withstand greater loss. Coffey and colleagues gauged shrinkage of the cortex by measuring the cerebrospinal fluid surrounding the brain. The greater the amount of fluid, the greater the cortical shrinkage.
Controlling for the health factors that contribute to brain injury, the researchers found that education was related to the severity of brain shrinkage. For each year of education from first grade on, subjects had an average of 1.77 milliliters more cerebrospinal fluid around the brain. For example, Coffey’s team reported, among subjects of the same sex and similar age and skull size, those with 16 years of education had 8 to 10 percent more cerebrospinal fluid compared with those who had four years of schooling. Of course, achieving a particular education level is not the definitive measure of someone’s mental capacity. And, said Coffey, education can be “a proxy for many things”. More-educated people, he noted, are often less likely to have habits, such as smoking, that harm overall health.
But, Coffey said that people should strive throughout life to keep their brains alert by exposing themselves to new experiences. Traveling is one way to stimulate the brain, and a less adventuresome way is to do crossword puzzles.
85．We can know from the first paragraph that___.
[A]Brains of the more-educated people may become more contracted when they get aged.
[B]Education may do harm to people’s brains.
[C]More educated people may suffer from brain tissue loss.
[D]The less educated can resort to more cognitive reserves when aged.
86． According to the second paragraph, it can be found by researchers that______.
[A]Only educated people suffer from brain shrinkage.
[B]The more the brain shrinks, the more abnormal people’s cognition and memory become.
[C] People might loss no mentality even with brain shrinkage.
[D] No brain-tissue loss will be induced by indulgence in alcohol
87． Which of the following is not mentioned in the text as one of the factors that may influence brain shrinkage?
[A]indulgence in drinking
[B]education
[C]emotional fluctuations
[D]hypertension
88． The text informs us that_____.
[A]Mental capacity is surely measured by education level.
[B]More－educated people never develop habits harmful to health
[C]People should keeping stimulating the brain to bear more brain-tissue loss.
[D]We should take less adventuresome way to stimulate the brain.
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