LOS ANGELES -- In findings that raise allegations of scientific fraud, the Food and Drug Administration has challenged an Arcadia, Calif., psychiatrist's widely publicized claim that an experimental drug sometimes causes "dramatic" improvements in patients with Alzheimer's disease.

The psychiatrist, Dr. William K. Summers, is being asked to respond to the allegations by the agency, which is considering whether to disqualify him from testing new drugs.

The FDA's findings call into question a 1986 New England Journal of Medicine article, of which Summers was principal author, on the drug THA, or tetrahydroaminoacridine, which is being evaluated in a national study of 300 Alzheimer's patients.

"There are numerous statements in your {Journal} article that appear to be false," Dr. Frances O. Kelsey, director of the FDA's Division of Scientific Investigations, said in a six-page letter to Summers.

For example, the detailed FDA review failed to verify claims that some patients disabled by Alzheimer's disease and then treated with THA were able to resume a variety of daily activities, including one who reportedly resumed his golf game.

"We were unable to identify the three subjects you claimed were able to resume homemaking, employment and golfing, i.e., those who had dramatic, meaningful improvement," Kelsey wrote in her Jan. 19 letter.

The FDA audit also turned up numerous alleged examples of missing and altered data, biased research methods, failures to protect the rights of research subjects and other inadequacies, according to the letter.

In some instances, patients had other illnesses, in addition to Alzheimer's, or were taking medications in addition to THA. This may have confused the results, the FDA said.

In one case, Kelsey said Summers had concealed the fact that 10 of the 12 patients in one phase of the study lived more than 2,000 miles from his office. "Medical monitoring was erratic and conducted mainly . . . with either family members who had a variety of perceptions or local physicians who, you concede, often did not follow your research protocol," the letter said.

Summers declined to be interviewed, but a spokeswoman released letters in which Summers wrote, "I do not agree with the FDA accusations." He also accused the FDA of attempting to achieve "a long-term hidden goal" of ending his project.

An FDA spokesman said the ongoing investigation will have no immediate effect on Summers' authorization to continue testing THA on about 40 Alzheimer's patients, or on the separate study of THA, which is being coordinated by Warner-Lambert Co., a Morris Plains, N.J., company that makes the drug.