Tranquilizers may sharpen elderly brains
SALT LAKE CITY, May 01, 2003 (United Press International via COMTEX) --
Tranquilizers much like Valium or Xanax someday could play a role in reversing
brain cell aging, an international team of scientists reported Thursday.
Experiments with the brain chemistry of what investigators believe are the
oldest monkeys in the world revealed such drugs briefly could help elderly nerve
cells act young again.
"It's counterintuitive. You can make grandpa move faster by tranquilizing him,"
neuroscientist Audie Leventhal of the University of Utah in Salt Lake City told
United Press International.
The researchers caution it is far too premature to start taking such drugs
before careful medical tests, "especially since Xanax is an abused drug anyway,"
Leventhal said. However, he remains hopeful treatments could one day improve the
declines in the senses and memory that come with old age.
"Brain function gets worse as we get older, pure and simple. It's not whether it
will get worse, it's a matter of how much worse it will get," Leventhal said.
"The ramifications of this are to correct brain degradation in the elderly. That
is significant to every human being."
Leventhal and colleagues looked at a colony of monkeys in China begun in 1950s
as part of a joint Chinese-Russian experimental program. At up to 30 years old
-- roughly 90 in human years -- these monkeys have lived about twice as long as
they do in the wild.
"They really do sort of look like grandpa. They have thinning hair and
wrinkles," Leventhal said. "They have a lot of the same problems we do. They
move slowly, they're not as attentive. They have cancers, bad teeth, graying."
In both monkeys and humans, aging is linked to declines in eyesight. While the
eye itself degenerates, prior studies revealed there also was nerve cell
degeneration within the visual cortex, the brain's image-processing center.
Leventhal recognized the chaotic electrical activity of these elderly monkey
nerves as resembling those of cells in newborn kittens. In those cat brains,
levels of a chemical known as GABA are low. GABA, or gamma-aminobutyric acid,
helps squelch brain activity.
"The analogy I use is that while you curse at every stop light in your life,
when you're driving in New York City or Boston, if you don't have stop lights,
green arrows or turn signals, you don't get anywhere. ... When you have a grand
mal epileptic seizure and nerves are firing like a son-of-a-gun, what's the
result of that? It's not too good. That's why GABA is there," Leventhal said.
Tranquilizers known as benzodiazepines -- such as Valium -- boost levels of
GABA. In findings appearing Friday in the journal Science, the researchers found
GABA enhancing drugs could, for a few minutes, reverse age-related nerve cell
deterioration.
He and colleagues in China probed electrical activity in 242 visual cortex nerve
cells in six young monkeys ages 7 to 9 years old, and 257 nerve cells in seven
old monkeys 26 to 32 years old. Monkeys watched computer screens displaying
vertical, horizontal or angled bars that moved at different speeds and
directions.
Normally, in young monkeys, horizontal bars triggered certain nerves to fire,
vertical bars made other brain cells active and diagonal bars set others off. In
older monkeys, nerve cells usually fired regardless of what direction the bars
were going in.
When the GABA-inhibiting drug bicuculline was given to young monkeys their brain
cells temporarily acted older by firing indiscriminately. On the other hand,
when the older monkeys were given either GABA or the GABA-enhancing drug
muscimol, which is derived from a toxic hallucinogenic mushroom, the older brain
cells behaved young again. Their drug-induced ability to discriminate motions
and shapes wore off five to 10 minutes after the drugs were stopped.
"We've actually put in patent applications for GABA and its enhancers to improve
brain function in the elderly," Leventhal said.
Auditory neuropharmacologist Don Caspary, of Southern Illinois University in
Springfield, found these findings "really interesting" and "very good."
"It suggests you could eventually have drugs to improve visual and auditory
systems in the elderly," although he remains skeptical whether it could help
memory and other brain functions, he told UPI.
The researchers hope others will investigate what doses of the dozens of
existing GABA-boosting drugs work best, or whether new drugs work better.
"We need to look at their various effects on different areas of the cortex,"
Leventhal said. There are different subtypes of GABA drugs also might work
against.
"It's absolutely remarkable to me that my lab is the only lab in the world
studying higher brain function in old monkeys. Old monkeys are rare, but the
world is full of old human primates," Leventhal said. "Hopefully we can drum up
a little interest and encourage other people who are trying to figure out how
come their kids are smarter than they are now."
(Reported by Charles Choi, UPI Science News, in New York.)
Copyright 2003 by United Press International.
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