image: University of Wisconsin Regional Primate Research Center
(movie will open in a separate window)
Neuroscientists may have found why the brain slows down in old age. As this
ScienCentral News video reports, researchers were able to temporarily reverse
aging in the brains of monkeys.
Got GABA?
Why do some elderly people have difficulty with vision, speech, and mobility?
Some neuroscientists have turned to monkeys for the answer, and believe it
might be because of a brain chemical called GABA.
“Our subjects were literally the world’s oldest rhesus monkeys,”
says Audie
Leventhal, professor of neurobiology and anatomy and adjunct professor
of physiology at the University
of Utah School of Medicine. “We chose rhesus monkeys because they
are, with the exception of the great apes, the animal species that has brains
that are closest to ours.”
The brain of a thirty-year-old rhesus monkey works a lot like the brain of
a ninety-year-old human. “The very old monkeys we studied exhibit behaviors
very similar to what very old people do,” Leventhal says. “In
addition to looking like old people, having grey hair, wrinkles, and so on,
they have cognitive declines. They don’t move as quickly. They have
more difficulty doing complex tasks as they get older.”
Leventhal explains in the May issue of
Science
that as we age, nerve cells in the brain become less “picky” about
which signals to respond to and which to ignore, and this could be because
our brains make less of a chemical called gamma-aminobutyric acid, or GABA,
as we get older. GABA inhibits, or screens out, stray neuron signals in the
brain. Without it, the brain is distracted and overwhelmed by all the stray
signals. “So the cells respond too strongly and more randomly,”
says Leventhal.
image: University of Wisconsin Regional Primate Research Center
Leventhal and his team exposed both young and old
monkeys to light patterns flashed on a computer screen, and studied nerve
cells related to the monkeys’ vision. In the younger animals, the large
majority of nerve cells responded to specific aspects of the visual stimuli,
like a certain color or shape, but the older monkeys' nerve cells responded
at random. Then the researchers gave the older monkeys GABA and a drug to
increase GABA, which, temporarily, seemed to reverse brain aging.
"We were able to have the cells respond more like cells do in younger
animals as long as we were delivering the GABA,” says Leventhal. “So,
if we did it for a few minutes, the cells responded properly for a few minutes.
If we did it longer than a few minutes, they responded longer than a few minutes.
When we discontinued giving the GABA to the neurons, within a minute or two
they began responding as they did previously.” The scientists also found
that giving GABA to the young monkeys had no effect, but blocking GABA in
these monkeys made their nerve cells less selective.
GABA
Supplements?
Before
you go out and buy up all kinds of dietary supplements with GABA,
a word of caution from Leventhal: "GABA itself does not pass
through the blood brain barrier, so eating it will be of little
value. Drugs that increase GABA inhibition
are potentially usefull."
Leventhal hopes to test GABA-boosting drugs in humans, which could make nerve
cells pickier in aging human brains. “If, in fact, older humans are
deficient in GABA, and don’t have enough inhibition in their brains,
you may actually be able to improve or speed up the operation of the old brain
by tranquilizing it, by using drugs that were developed as tranquilizers.
No one has ever thought of that before, because the last thing you want to
do to your grandfather is tranquilize him because he’s moving too slowly.”
Tranquilizers like
Valium
and Xanax
boost GABA levels, but they are also addictive.
As medical advances help people to live longer, researchers say it's important
that we find ways to keep the brain healthy longer as well. “There should
be many, many more groups worrying about what happens to our higher brain
functions when we get old,” says Leventhal. “I personally don’t
want to be 110 and not have my mental capacity anymore. I’ve sort of
enjoyed my brain for the first half a century that I’ve been alive,
and I would like to keep it for another half a century.”
delicious
digg
magnolia
reddit
newsvine
netscape
netvibes
