Tests on a drug that promised help to millions of Alzheimer's disease sufferers were halted because of serious side effects in some people, a Food and Drug Administration spokesman said yesterday.

Tests on the experimental drug, THA, were stopped Friday at the request of the FDA after federal health experts and the drug's manufacturer discussed the discovery of "liver toxicity" in some patients, FDA spokesman William Grigg said.

The drug manufacturer, Warner Lambert Co. of Morris Plains, N.J., "suspended the testing at least temporarily while they check signs of liver toxicity," Grigg said.

"These are blood chemistry signs of something going on. It doesn't mean someone got sick or hurt by it. Its an early indication," he said. "You study that and take a good look at it and see what's going on to prevent something. My understanding is that there were some elevations of the liver {enzyme} chemistry of seven patients."

Grigg said the halting of such tests is "generally not a matter of ordering," by the FDA, "it's a matter of them and us talking {although} we certainly do have power to suspend it."

Alzheimer's disease is a gradual, irreversible erosion of brain cells that control thought and memory. Victims usually begin with difficulty remembering simple things and regress to an infant-like state, needing round-the-clock attention. They sometimes become violent.

The disease affects an estimated 1.2 million to 4 million middle-aged and elderly Americans and about half the people in nursing homes. It kills 120,000 people a year.

First reports of the tests suspension appeared yesterday in the Akron (Ohio) Beacon Journal.

The tests had been conducted by Warner Lambert with FDA approval in 17 centers around the country and were to have been expanded.

The patients found with elevated liver enzyme chemistry were in centers in St. Louis; Worcester, Mass.; Springfield, Ill.; Durham, N.C., and Los Angeles.