IF YOUR grandparents are becoming a bit forgetful, it might be because
getting old is stressing them out.
快猫短视频s believe that memory deteriorates during normal ageing because
older people cannot grow new neurons in the brain鈥檚 hippocampus. These new brain
cells are needed to form memories about recent events.
Ron McKay and Heather Cameron at the National Institutes of Health near
Washington DC wanted to find out why the neurons stop dividing in old age. They
knew that levels of stress hormones known as corticosteroids are often up to
three times as high in elderly people as in younger adults. They also knew that
stress in younger people can temporarily impair memory. So they wondered whether
removing stress hormones might improve old people鈥檚 memory.
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To test their idea, they took young adult rats and older rats and removed all
their adrenal glands, which produce most of the corticosteroids. Then they
examined how many new neurons formed in the rats鈥� brains.
It turned out that the neurons divided much more in the absence of stress
hormones鈥攁nd the effect was just as marked in the elderly rats as in the
younger ones. 鈥淭he result is really dramatically clear,鈥� says McKay. The finding
shows that the capacity to grow new neurons is there well into old age, but it
is blocked by stress hormones (Nature Neuroscience, vol 2, p 894).
This opens up the possibility of designing a family of drugs that block the
effects of stress hormones in the brain, allowing neurons to sprout and memory
to stay healthy. Says McKay: 鈥淚 actually think that I am going to get a couple
of phone calls from drug companies.鈥�