衛生類B級：閱讀理解High Stress May

　　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(海馬區)， 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(腎上腺) 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(腎).

　　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(病態的) 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.