A widely prescribed drug for Alzheimer's disease does not work and may actually accelerate the mental deterioration of sufferers, a team of researchers reported yesterday.

The drug, ergoloid mesylates -- sold under the brand name Hydergine -- contains chemicals that were supposed to help the nerve cells in the brain communicate with one another.

"The results of this study raise major doubts about the value of ergoloid mesylates for this disease," said the team, led by Troy L. Thompson II, professor of psychiatry and human behavior at Jefferson Medical College in Philadelphia. Their research, to be published in today's edition of the New England Journal of Medicine, was funded by the Sandoz Research Institute. Sandoz sells Hydergine, the only drug approved for Alzheimer's by the Food and Drug Administration.

When the drug was given to 39 patients suffering from the disease, they did no better than 41 who received a placebo over a period of up to 24 weeks. Thompson said researchers were surprised to discover that people who took the drug seemed to lose their mental skills faster than those on a placebo.

Earlier tests may have misled investigators into believing that Hydergine worked, he said, because researchers studied fewer patients for a shorter period of time, or because their mental deterioration could have been caused by a medical problem other than Alzheimer's.