High Stress May Damage Memory
According to a report issued in May 1998, elderly people who have consistently high blood levels of cortisol don’t score as well on memory tests as their peers with lower levels of the stress hormone. What’s more, high levels of cortisol are also associated with shrinking of the hippocampus, a region of the brain that plays a key role in learning and memory.
The findings suggest that even cortisol levels in the normal, “healthy “range can actually accelerate brain aging.
The study results “now provide substantial evidence that long-term exposure to adrenal stress hormones may promote hippocampal aging in normal elderly humans, “write Nada Porter and Philip Landfield of the University of Kentucky in Lexington in their editorial. Cortisol is a hormone released in response to stress by the adrenal glands, which sit on top of the kidneys.
Over a 5 to 6-year period. Dr. Sonia Lupien and his colleagues measured 24-hour cortisol levels in 51 healthy volunteers, most of whom were in their 70s.
Despite wide variation in cortisol levels, the participants could be divided into three subgroups: those whose cortisol progressively increased over time and was currently high (increasing/high); those whose cortisol progressively increased over time and was currently moderate (increasing/moderate); and subjects whose cortisol decreased, but was currently moderate (decreasing/moderate).
The researchers tested the volunteers’ memory on six people in the increasing/high category and five people in the decreasing/moderate group. The groups did not differ on tests of immediate memory, but the increasing/high cortisol group had other memory problems compared with those in the decreasing/moderate group.
The researchers also found that the total volume of the hippocampus in those in the increasing/high group was 14% lower than those in the decreasing/moderate group, although there were no differences in other brain regions.
The results suggest that “. . . brain aging can be accelerated by levels of adrenal hormones that are not generally regarded as pathological and that variation within this normal range is related to variation in the rate of brain aging,” write Porter and Landfield. “This further suggests that chronic stress may accelerate the worsening of hippocampus.”
1. The part of the brain important for a person’s learning and memory is
A. the cortisol.
B. the adrenal glands.
C. the stress hormones.
D. the hippocampus.
2. When the levels of cortisol go higher, the hippocampus in the brain may
A. become larger.
B. become smaller.
C. be missing.
D. be totally damaged.
3. According to the article, when people feel too worried or nervous or when they overwork,
A. the adrenal glands will produce a stress hormone.
B. the kidneys will produce adrenal glands.
C. the hippocampus will produce high levels of cortisol in the blood.
D. the cortisol will produce something that makes a poorer memory.
4. When the total volume of the hippocampus becomes smaller, other brain regions
A. become smaller too.
B. become larger.
C. may remain the same in size.
D. may be damaged.
5. Porter and Landfield’s research shows that
A. the change in the levels of adrenal hormones has nothing to do with the degree of brain aging.
B. the change in the levels of adrenal hormones has a lot to do with the degree of brain aging.
C. the long-term stress will gradually make the hippocampus worse.
D. None of the above is correct.
FDA: Human, Animal Waste Threatens Produce The biggest food safety risk for fresh fruits and vegetables as they are grown, picked or processed comes from human and animal waste, the U. S. Food and Drug Administration (FDA). said Friday. More than 9, 000 Americans die each year from food-borne diseases and some scientists believe fresh produce is the biggest carrier of contamination. The FDA issued a set of draft guidelines for U. S. and foreign growers to carefully monitor worker hygiene, water quality, manure management and transportation. These 34-page draft guidelines urged growers to give workers lessons on basic hygiene such as using soap to wash their hands, covering wounds that could come into contact with produce, and using only clean toilets. The FDA guidelines identified “the major source of contamination “for fresh produce as human or animal feces. “We think just proper controls and proper attention to detail would make a big difference in food safety,” said and FDA official, “It is our belief that these guidelines would not be very costly.” But grower groups disagreed with the FDA’s assessment. “Most food-borne disease outbreaks that happen further down the distribution line are due to contamination because people preparing food are not properly washing their hands, “said Stacey Zawal, an official with United Fresh Fruit and Vegetable Association. “That is not necessarily true for growers and packers.” Some U. S. grower organizations have expressed concern that the agency is interfering with on-farm practices. Others object to the FDA’s proposal to have growers formally document the picking, handling and transportation of produce so that health officials could quickly recall foods if necessary. Consumer groups criticized the FDA guidelines as of little use because they will not carry the force of law. But stricter regulations could evolve as researchers find new technology or methods to kill harmful bacteria or parasites, the FDA said. The FDA recommendations are due to be made final by the FDA later this year for use by U.S. and foreign growers. The matter of encouraging foreign growers to adopt the guidelines remains somewhat tricky but FDA officials say it is vital because of the huge amount of imported produce. 1. “Food-borne diseases” in this essay means those diseases A. which people get by eating fruits which have been polluted B. which people get by eating too many kinds of food. C. which many kinds of fruit get when polluted by feces. D. which fruit-growers get by their failure to keep themselves clean. 2. Some fruit grower groups believe that most food-borne diseases are caused by A. growers’ lack of attention to personal hygiene. B. lack of effective guidelines. C. the FDA’s decision to import more foreign fruits and vegetables. D. people involved in distributing fresh produce. 3. An FDA official said that putting the guidelines into practice A. would be too costly to be effective. B. would not cost any money. C. would not be very expensive. D. would needs lots of money. 4. Consumer groups criticized the FDA guidelines because they didn’t think that these guidelines A. had won enough support from the farmers. B. had been written with strict regulations. C. would surely be carried out. D. included new technology. 5. The last paragraph suggests that A. some tricks need to be adopted to encourage foreign growers to follow the FDA guidelines. B. a good way should be found to encourage foreign growers to follow the FDA guidelines. C. foreign growers consider the guidelines to be of great importance to them. D. it is almost impossible to ask foreign farmers to follow the guidelines.
