Rep. Daniel J. Flood (D-Pa.), long one of the most powerful men in Congress, was depicted in federal court here yesterday as a shattered man whose mental capacities have deteriorated over the last several years because of a combination of drug addiction and illness.

In a report by Dr. James L. Foy, professor of psychiatry at Georgetown University Hospital, the 75-year-old Flood is described as suffering from depression, memory lapses that bring him close to tears, and a variety of other mental ailments that raise questions about his ability to stand trial on multicount conspiracy, bribery and perjury charges.

U.S. District Court Judge Oliver Gasch immediately postponed Flood's Dec. 3 trial to give two government psychiatrists a chance to examine the congressman.

Flood, who was the longtime chairman of the House Appropriations subcommittee on labor-health, education and welfare, is charged with taking $65,000 in bribes from several businessmen in return for his help in getting them federal grants. His first trial ended in mistrial last February when one juror held out, saying Flood was too old to go to jail.

Effort to set a second trial date have been complicated because Flood has been hospitalized several times for exhaustion, and eye and gall bladder surgery. On Wednesday Flood announced his retirement from Congress effective Jan. 31, citing "health reasons."

While his physical health has been an issue before, Flood's mental health and drug dependence were not publicly known until his attorney, Axel Kleiboemer, told the court yesterday about the psychiatric reports.

Foy's six-page evaluation said Flood has a history of drug-dependency going back at least a decade, resulting from use of barbiturate sleeping pills, sedatives such as Valium and Sinequan, and pain-killers such as Demerol.

Dr. Barry A. Bukatman, a Bethesda psychiatrist who also examined Flood, agreed with Foy that Flood "has a long standing history of overuse of sedatives, opiates and alcohol." He added that Flood has seen so many doctors over the years "it is impossible to get a clear picture of what his use or misuse of medications has been."

For instance, Bukatman said, medical records from the office of the attending physician of the Capitol "show multiple prescriptions for Dalmane, Tuinal, Seconal, phenobarbital, Librium, Valium, Menprobamate, Elavil and Sinequan."

Foy wrote that Flood told him he "cannot do without" his sleeping pills. The doctor recommended that the congressman be hospitalized for "the gradual withdrawal of all sedative-hypnotic and tranquilizing drugs" though he noted that "this could be dangerous and life-threatening in his case because of age and the barbiturate dependence itself."

Flood associated his depression over the last five years with "his perception of failing powers of voice, presence and intellectual sharpness" and has contemplated suicide, Foy's report said.

The congressman's family doctor, attorney and chief staff aide described "the gradual decline and transformation of a once confident, imposing and theatrical politician to a state of agitated helplessness and indecision," Foy said.

Flood's judgment on whether to sit in a chair or lie in a hospital bed, the psychiatrist added, is "riddled with anguishing indecision and childish helplessness."

Flood has long been known publicly for his waxed handlebar mustache, flamboyant dress and Shakespearean-actor voice. Even while surrounded by the bribery charges in the last two years he has held press conferences, attended testimonial dinners in his honor, and won reelection.

"Dan Flood has been playing Dan Flood," one who has watched his behavior said yesterday. "There's been no substance, only appearances, for the past several years."

Attorney Kleiboemer said Flood's drug addiction and mental health problems weren't raised until now because he didn't have "concrete evidence" until recently. He said he hadn't had time to pursue the medical questions with extensive psychiatric exams before the first trial because he was occupied with preparing the defense.