Chemical briefly boosts aging brains

WASHINGTON - Aging brains may be sharpened and, in effect, made young again briefly by increasing the levels of a neurochemical called GABA, a study suggests.

Researchers at the University of Utah found that GABA appears to help extremely old Rhesus monkeys focus their vision and thinking processes by silencing the static from other neurons.

GABA screens out the stray brain signals that may make thinking and seeing difficult in older brains, said Audie G. Leventhal, a professor at the University of Utah School of Medicine.

"It eliminates the garbage signals," said Leventhal, first author of the study that appeared Friday in the journal Science.

Leventhal said that in old primates, both human and monkey, there is a decline in the levels of GABA, a chemical that inhibits neuron signals in the brain. Without enough of that control, he said, the brain is distracted and overwhelmed by stray signals, in the same way the ear is overwhelmed when trying to hear a whisper at a rock concert.

"There, you wouldn't really hear anything," he said. "But if there is screaming in an empty room, then it is very easy to hear. That is sort of what GABA does."

Without sufficient levels of GABA to drown out all of the background signals, said Leventhal, "then all of your higher brain functions go bad."

In the study, Leventhal and his co-authors measured the electrical activity of neurons in specific parts of the brains of six young monkeys, ages 7 to 9, and seven old Rhesus monkeys, ages 21 to 32, as the animals were exposed to light patterns flashed on a computer screen.

When minute quantities of GABA were injected directly into neurons, the brains of the older monkeys responded just like those of the young animals, Leventhal said.

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