High Stress May Damage Memory
According to a report issued in May 1998， elderly people who consistently
high blood levels of the stress hormone. Whats 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(腺)， 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 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.
6 which of the following plays a key role in ones learning and memory?
A the kidneys
B the adrenal hormone
C the stress hormone
D the hippocampus
7 when the levels of cortisol go high ，the hippocampus
A may expand
B may shrink
C may disappear
D may function better
8 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
9 it app ears 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
10 the research conducted by porter and land field 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
C chronic stress may strengthen ones memory
D the rate of brain aging always remains stable