Hi all , found this in the NY Times ,

        Is Memory Loss Inevitable? Maybe Not
         By LINDA CARROLL

             Ruth Arnold can recall a time when her memory was perfect.
Years
              ago, working as a college reference librarian, she could put
her finger
              on any piece of minutia at will. "I remembered all the books
and what
         was in them," Mrs. Arnold said.

         At the moment, it is still thought to be generally true that older
people do not
         remember as well as younger people. Dr. Denise C. Park, a professor
of
         psychology and a senior research scientist at the Institute for
Social Research
         at the University of Michigan in Ann Arbor, says that when young
and old
         people, ranging in age from 20 to 90, are asked to listen to a
series of
         numbers and letters and then reverse the series, young people can
remember
         and manipulate longer lists faster.

         Older people also appear to have more attention problems. Dr.
Sandra
         Weintraub, associate professor of psychiatry and neurology and
clinical core
         director of the Alzheimer's Disease Center at Northwestern
University, found
         a conspicuous different between older and younger people in a
driving
         simulation experiment. The older group -- both those with good
memories
         and those with early Alzheimer's -- were more easily distracted by
passing
         objects and scenery than the younger group. But, studies have also
shown
         that more than a third of the elderly can remember the names and
events in
         their lives as sharply as their 20-year-old counterparts,
suggesting that
         memory loss is not necessarily inevitable.

         At research centers around the country, scientists are trying to
tease out the
         underlying causes for non-Alzheimer's-related memory loss and,
ultimately,
         to find a cure. In one lab, researchers have improved the memories
of older
         mice by tweaking certain neurotransmitter levels.

         In another lab, investigators studying the effects of stress on
memory have
         found that the neurons needed for memory shrink in response to high
levels
         of stress hormones. Long-term exposure to stress may lead to
permanent
         changes in the brain, some experts think.

         Still other researchers are studying identical and fraternal twins
to discover
         whether some people are genetically programmed to become forgetful
with
         old age. Early indications are that genes do play some role,
although experts
         debate how important it is.

         Ultimately, scientists may discover that age-related memory loss
may be a
         result of a combination of bad genes and a hard life. "I think it's
a
         nature-nurture interaction, in large part," said Dr. Bruce S.
McEwen,
         professor and head of the laboratory for neuroendocrinology at
Rockefeller
         University in New York. "A genetic vulnerability increases the
likelihood that
         experience will have an effect."

         Researchers only recently learned that "normal" age-related memory
loss
         might involve a different part of the hippocampus, a small
structure in the
         middle of the brain, than Alzheimer's disease.

         Several decades ago, scientists learned that the hippocampus was
central to
         learning and memory. In surgery to cure epilepsy, doctors removed
the
         hippocampus from a man, curing him of seizures, but leaving him
unable to
         store new memories.

         It was equivalent to having no save function on a computer, said
Dr. Scott A.
         Small, an assistant professor of neurology at the Columbia College
of
         Physicians and Surgeons in New York. One has the information as
long as it
         is on the screen, but once something new flashes on the monitor,
the old data
         are lost.

         "If you met this man at a dinner party, he would know who you were
as long
         as his attention was focused on you," Dr. Small said. "If his
attention was
         diverted in the middle of the conversation, he would look at you as
if he'd
         never met you before."

         Dr. Small and his colleagues have been using functional M.R.I., an
imaging
         system sensitive to the activity of nerve cells, to get a closer
look at how
         Alzheimer's disease and mild age-related memory loss affect the
brain. In one
         experiment, the scientists put people into a functional M.R.I.

         and then watched as neurons sparked in different regions of the
hippocampus
         when the people remembered others' faces.

         Scans from Alzheimer's patients showed next to no neuronal activity
in a
         section of the hippocampus called the entorhinal cortex as well as
a variety of
         other regions.

         Studies have shown that the entorhinal cortex is the first area of
the
         hippocampus to be damaged by Alzheimer's.

         But, in people with mild memory loss, the results were different.
In 8 of 12
         people, the entorhinal cortex flashed brightly, while another
region, called the
         subiculum, also in the hippocampus, glowed dully. The other four
people had
         less activity in the entorhinal cortex, but still more than those
with
         Alzheimer's.

         The researchers suspect that those four people may have early
Alzheimer's.
         They will follow the 12 to see if it is possible to predict who is
at risk of
         developing the disease.

         Dr. Small and others suspect that the non-Alzheimer's related
deficits in
         memory are a result of faulty wiring rather than actual nerve-cell
death.
         Studies have shown that while the brain shrinks in size, the number
of cells
         stays relatively constant. So, researchers now think that there is
either a
         scarcity of certain crucial neurotransmitters or that receptors
designed to
         take up these brain chemicals are malfunctioning.

         Whether the cause of the wiring problem is genes or environment is
the
         matter of some debate.

         "This is the million dollar question," said Dr. Richard Mayeux, a
professor of
         psychiatry and public health and director of the Taub Institute on
Alzheimer's
         Disease and the Aging Brain at Columbia.

         "There are suggestions from all over that mental function is a
heritable trait,
         albeit a complex one."

         For example, Dr. Mayeux said, studies that followed twins found
that even in
         their 80's, identical pairs were often more similar with respect to
memory
         than fraternal twins. "This doesn't mean that we will identify one
particular
         gene that controls preservation of memory, but it really points to
memory
         being a heritable trait," Dr. Mayeux said.

         While allowing that heredity may play a role in memory loss, other
         researchers have focused on a host of environmental factors,
including
         stress, sex hormones and blood flow to the brain.

         Large population studies have implicated stress in memory loss. A
10-year
         MacArthur Foundation study found that "self-efficacy," along with
physical
         and mental activity, predicted good memory in old age.

         "What we called self-efficacy has to do with the control people
feel over their
         lives, whether they feel they can do something to influence what
happens in
         their daily lives,"' said Dr. Marilyn S. Albert, a professor of
psychiatry and
         neurology at Harvard.

         "This general feeling of control, we can think of as a sort of
anti-stress."

         So far, laboratory researchers have looked only at the effects of
short-term
         stress, which appear not to be permanent.

         "In our animal model of stress, you can largely reverse the effects
of stress
         as long as it hasn't gone on for a number of weeks," Dr. McEwen of
         Rockefeller University said. "This is actually a gray area. We
don't know yet
         how long it takes before you produce permanent brain damage."

         But Dr. McEwen says the kinds of stresses generated by tight
deadlines and
         high pressure jobs are probably not enough to seriously affect the
memory.

         "More likely it's the kind of stress experienced by a person at the
low end of
         the totem pole, in a meaningless job, in a lousy environment, with
bad
         interpersonal relationships," Dr. McEwen said.

         "It comes from a sense of hopelessness, helplessness, despair and
         depression.'

         Researchers have looked at other possible culprits to explain
age-related
         memory loss. Studies of post-menopausal women have linked low
levels of
         estrogen and testosterone to memory decline. Some think a byproduct
of
         oxygen metabolism -- free radicals -- could be toxic to memory
brain cells.
         Or the brain may simply be starving to death as blood supply from
the heart
         decreases with age.

         Some researchers, rather than looking for causes, are seeking
treatments. In
         another Columbia laboratory, researchers are improving the memories
of
         mice with injections of a drug similar to dopamine. If young mice
are put in a
         maze several days in a row, most will learn where the escape route
is and go
         right to it, said Dr. Eric L. Kandel, a professor at Columbia. If
middle-aged
         mice, those 12 to 14 months old, are in the same maze for several
days,
         fewer of them will remember how to negotiate their way out. But
when the
         middle-aged mice are given the dopamine substitute, their memories
improve.

         "It's not a fountain of youth, but it restored most of their
function," Dr.
         Kandel said. "The idea that we will one day come up with a drug
that cures
         all memory problems is a dream. I think it's a decade away, at
least."
                   Copyright 2000 The New York Times Company
--
Cheers,
Joao Paulo - Salvador,Bahia,Brazil
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