- Your brain may show significant signs of aging by the
time you are 40, new research has found.
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- Bruce Yankner, a Harvard Medical School researcher, has
discovered that many genes, including several key ones associated with
memory and learning, become damaged and stop working as people age, and
the slowdown can begin as young as 40. His work could help explain why
many people lose their keys more often as they get older, or have trouble
summoning a word that is on the tip of their tongues. It may also offer
clues into age-related diseases such as Alzheimer's.
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- Dr. Yankner performed a complicated molecular analysis
on the brains of 30 individuals aged 26 to 106 years old. They died from
a variety of medical and accidental causes. Their brains were normal for
their age, and came from brain banks across the United States.
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- Using new screening techniques, he was able to document
which genes were hard at work in their brains before they died.
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- Genes, found in every cell in our body, contain the instructions
for proteins. In the case of the brain, these proteins are what keep it
functioning.
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- Dr. Yankner found that roughly 180 genes, including about
20 known to play a role in learning, memory and other cognitive functions,
were badly damaged in the brain cells taken from people over 70. Those
same genes were working normally in the brains taken from people under
40.
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- Between 40 and 70, however, there was huge variability.
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- "Some middle-aged individuals exhibit gene patterns
that look more like the young group, whereas others show gene patterns
that look more like the old group," Dr. Yankner said in an interview.
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- This makes sense, he argued, because some people appear
to age much faster than others.
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- "One interpretation, is young adults age at similar
rates initially, but when they enter middle age they diverge and approach
old age at different rates. You walk into the coffee shop and look at three
middle-aged people. They could all look the same age but they could be
years apart."
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- He also noticed a second distinct pattern in gene activity
in the brain. As people age, genes involved in repairing damage in the
brain, including genetic damage, increase significantly.
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- "One potential scenario is that we all go through
this degenerative change, but how the brain compensates differs from individual
to individual and may determine individual outcomes."
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- Further study may yield clues about why some people seem
to age so much more rapidly than others. Dr. Yankner is also investigating
whether these seemingly normal changes in the brain may play a role in
age-related diseases such as Parkinson's and Alzheimer's.
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- It may be that people who develop these diseases don't
have an adequate repair mechanism to deal with the genetic damage that
comes naturally with aging. It may one day be possible to identify who
is most at risk, and to take measures to help them avoid problems later
on, Dr. Yankner said. It could be that lifestyle plays a role, or it may
be possible to develop drugs that could help.
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- Working with brain tissue in the lab, the researchers
were able to use genetic engineering to repair the damage to the genes
involved in memory and learning.
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- "We can repair these aging genes in the laboratory,
but that is a far cry from the human brain. This is only a first step,"
Dr. Yankner said.
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- His study was published on-line yesterday by the journal
Nature.
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