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 interfering 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 appearing 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.”
GABA drowns out garbage?
Without sufficient levels of GABA to drown out all of the background signals, said Leventhal, “then all of your higher brain functions go bad.”
Dr. Bernard W. Agranoff, a neurochemist and professor of psychiatry at the University of Michigan, said the study showing the effect of GABA in aging brains is an important finding that should be researched further in humans.
“It doesn’t automatically point toward a treatment, but it is an observation that needs to be followed up,” said Agranoff, who was not involved in the research. “It is a quite interesting finding and the data looks very good.”
In the study, Leventhal and his co-authors measured the electrical activity of neurons in specific parts of the brains of both young and old Rhesus monkeys as the animals were exposed to light patterns flashed on a computer screen.
Earlier work had shown that in young monkeys some neurons fired only for horizontal patterns, while others responded only to vertical or to diagonal patterns. In older monkeys, however, the neurons fired almost randomly, suggesting the brain cells had a diminished ability to distinguish shapes and motions.
Small amounts helped
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. Signals were sharp and clean as neurons fired appropriately for each of the patterns on the screen, he said.
The effect lasted only as long as GABA levels were maintained. When the chemical was removed, the brains of the old monkeys reverted to their aged confusion within a few minutes, Leventhal said. Added GABA appeared to have no effect on the young.
The tests were conducted on six young monkeys, age 7 to 9, and on seven old monkeys, age 21 to 32.
“These monkeys age about three times faster than humans,” Leventhal said. “A 30-year-old Rhesus is equal to about a 90-year-old person.”
Tranquilizers increase GABA
Some tranquilizers, such as Valium, Xanax and Librium, increase the levels of GABA in the brain of human patients. This suggests that these drugs might sharpen aged minds, but that is an idea that first must be carefully tested, Leventhal said.
“The idea is counterintuitive,” he said. “The idea that to get grandpa to move faster you have to tranquilize him isn’t something that makes a lot of sense without these results.”