WASHINGTON (AP) _ A new drug, which in some tests of healthy elderly men restores memory almost to that of young people, soon will be tested on patients with Alzheimer's, the fatal brain disorder that destroys the mind.

Dr. Gary Lynch of the University of California at Irvine said Sunday the drug called ampakine CX-516 accelerates signals between brain cells and appears to significantly sharpen the memory.

The drug, used in only mild doses, was tested on students in their early 20s and on men aged 65 to 70 and the results were "particularly striking" among the older people, Lynch said. He delivered a report on the drug Sunday at a national meeting of the Society for Neuroscience.

Lynch said clinical trials of the drug consisted of memory tests conducted with and without CX-516.

Before taking the drugs, the subjects were read a series of nonsense syllables, then asked five minutes later to recall as many of them as possible.

The elderly could recall, on average, only one of the syllables. The score for the young men averaged four out of 10.

The subjects later were given mild doses of ampakine CX-516, then retested.

"The results for the 65- to 70-year-old men was particularly striking," said Lynch. "They scored near the range of young people."

In some tests even the young experienced improvement in memory by about 20 percent, he said.

Lynch said the hope is that the drug will improve the memory of patients with Alzheimer's disease, a progressive disorder that destroys memory and other functions of the brain and eventually kills. About 5 million Americans, mostly elderly, have Alzheimer's, and it is estimated that the number will climb to 15 million over the next quarter-century as the nation's population ages.

Ampakine CX-516 has been tested only on small groups in clinical experiments to detect any toxic effects. A more definitive test will start next year at the National Institutes of Health, when 16 patients with mild to moderate Alzheimer's disease will be given the drug.

Dr. Donald Price, a neuroscience researcher at Johns Hopkins University in Baltimore, said the new drug is "intriguing and innovative" and that it will influence "a very important synapse" in the brain.

However, he said, "I have reservations about its use in Alzheimer's, because it does not directly address the disease mechanism. It is a palliative."

"I would suspend my enthusiasm until I see the results of the clinical trials. It is quite early" in the drug development process, Price said.

Lynch and co-workers at the University of California, Irvine, discovered the drug in 1991 while searching for compounds to improve communications between neurons in the brain. He said it works by causing neuron switches, called synapses, to remain open for a fractional second longer. This enhances the flow of an amino acid called glutamate. The exchange in effect carries a message from one neuron to another.

In 1993, ampakine CX-516 was tested on laboratory animals. Researchers found that older rats given the drug had a dramatically improved ability to find their way out of a maze and to remember the route later.

"It reduced the training session for older rats from 10 to five," said Lynch.

Human trials of the drug started last year. Results will be published in January in the journal Experimental Neurology.

Tests on humans, using very low doses of the drug, also were conducted using photograph recognition, odor recollection and learning a pencil maze. In all of these tests, the subjects performed better with ampakine than without it.

Lynch said the improvement in memory may be even better with higher doses of the drug. This will be done only after early tests prove the drug has no harmful side effects.

People with the greatest amount of memory deficit seemed to benefit most from the drug, which makes it promising for Alzheimer's disease. Lynch said that though the drug appears to sharpen memory, there is no indication that it will effect some of the behavioral aspects of Alzheimer's that are not associated with memory.

Ampakine CX-516 is licensed to an Irvine, Cal., company, Cortex Pharmaceuticals Inc., and Lynch said he has an interest in the firm. Human trials starting next year will be under the control National Institutes of Health scientists.

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