WASHINGTON (AP) _ Muhammad Ali says he must take medication every three hours to relieve some of the symptoms of Parkinson's syndrome, but he insists he is not brain- damaged and his slurred speech comes from fear of crowds.

''It's unfortunate that people have an image of me as a legendary figure ... and if they see me as anything less than Superman, they can't accept it,'' he said in an interview published today in The Washington Post.

The former three-time heavyweight champion said he is frustrated that he can't demonstrate to people that he is not brain-damaged and that he is hurt when people talk about him in his presence as if he doesn't understand them.

''I bet you're surprised I'm talking this good,'' Ali said to a Post reporter during the telephone interview. ''See, I'm not stupid. I'm not brain- damaged. The mind is good. ... The difference now is that I don't feel so crowded.''

''When it's crowded, I feel pressure and I just can't project,'' he said.

Ali was in Washington to attend a Capitol Hill news conference Tuesday to announce the appointment of a friend, Stephen Saltzburg, to a Justice Department post.

Doctors have said Ali's illness is a progressive neurological degeneration related to Parkinson's disease that was caused by blows he suffered during his boxing career. Parkinson's disease is a potentially fatal condition that causes gradual loss of muscle control, sometimes leading to the slurred speech that has been the source of rumors about Ali being brain-damaged.

Ali said the medication he takes every three hours ''makes a real difference'' in how he feels. He wouldn't discuss the treatment in detail, but said his speech shows it if he deviates from the regimen.

''God gave me this physical impairment to remind me that I am not the greatest. He is,'' he said.

During the wide-ranging interview, Ali also spoke of Jesse Jackson's presidential campaign and Soviet leader Mikhail S. Gorbachev.

''I like Jesse, but I think his timing's off,'' he said.

''He needs to prove that he is not just a cheerleader. He should run for office and get himself elected governor or senator. I think it's too big a responsibility for him to be the leader of the free world right out of the starting gate.''

About Gorbachev, Ali said: ''If it's all a show, he's a better actor than Ronald Reagan.''