According to a report issued in May 1998, elderly people who consistently
high blood levels of the stress hormone. What's more, high levels of cortisol
are also associated with shrinking of the hippocampus (海马区), 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 (肾上腺) stress hormones
may promote hippocampal aging in normal elderly humans, " write Nada Porter and
Phillip Landfield. Cortisol is a hormone releases in response to stress by the
adrenal glands(N), which sit on top of the kidneys (肾). Over a
5 to 6 year period, Dr. Sonia Lupine and his colleagues measures 24-hour
cortisol levels in 51 healthy volunteers, most of whom were in their
70s. 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 in 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 (病态的) 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 the hippocampus.
单选题
Which of the following plays a key role in one's learning and memory?
A. The kidneys.
B. The adrenal hormone.
C. The stress hormone.
D. The hippocampus.
【正确答案】
D
【答案解析】
单选题
When the levels of cortisol go high, the hippocampus ______.
A. may expand
B. may shrink
C. may disappear
D. may function better
【正确答案】
B
【答案解析】
单选题
According to the passage, when people are under stress ______.
A. the adrenal glands will produce cortisol
B. the kidneys will shrink rapidly
C. the hippocampus will produce cortisol
D. the brain will work more efficiently
【正确答案】
A
【答案解析】
单选题
It appears that when the hippocampus shrinks sue to high levels of
cortisol, other brain regions ______.
A. may change dramatically
B. may stop functioning
C. may remain unaffected
D. may be seriously damaged
【正确答案】
C
【答案解析】
单选题
The research conducted by Porter and Landfield showed that ______.
A. the levels of adrenal hormones have nothing to do with brain aging
B. changes in the levels of adrenal hormones can affect brain aging