ALTERED STATES -- At the Uptown and the Springfield Mall.

Whatever else is wrong with "Altered States," it isn't boring.

Ken Russell's film version of Paddy Chayefsky's novel about altering states of consciousness is ridiculous -- nay, preposterous -- and is loaded down with pseudo-Freudian, quasi-mystical mumbo-jumbo. But if you can get past that and relax, you can have a lot of fun.

Actually, it's hard to relax when you're sitting bolt upright in your chair.

Russell, using humor, violence, suspense and lightning dialogue, doesn't let you rest for a minute.

To quote one enthusiastic member of the preview audience: "You have to accept whole boatloads of bull with this flick, but wow, what a trip!"

William Hurt is Eddie Jessup, a Harvard psychology professor with an insatiable curiosity about the two-thirds of the human brain that scientists haven't uncovered a use for. He floats in isolation tanks to induce trances, travels to Mexico to participate in a Castaneda-esque secret mushroom ceremony and then combines the two experiences, whereupon the fun starts.

"Some of these tank trips can get pretty creepy," says Jessup's trusty assistant Arthur (Bob Balaban) in the understatement of the movie. Jessup regresses to a quasi-simian state, to the horror of his anthropologist wife, Emily (Blair Brown). Lest that sound too clinical, be assured that Jessup's ape antics are outrageously funny. Sort of a "Teenage Werewolf Meets the Incredible Hulk."

With his watery, flickery eyes, tight little mouth and disarming smile, Hurt makes a sensational madman. Brown is equally convincing as his strong-willed wife, the only person who can save him from himself. She knows he's weird ("I feel like I'm being harpooned by a raging monk," she says of their sex life), but is irresistibly, irrevocably drawn to him. Their friends can't understand it: "She's still crazy about him. (pause) He's still crazy."

Chayevsky deflects criticism by anticipating it: "I didn't think anybody was doing these kinds of experiments any more," says Charles Haid as a skeptical scientist who nevertheless goes along with Jessup's mind games. "I thought all this isolation-tank stuff went out in the '60s with Timothy Leary and all the other gurus," huffs another unimpressed colleague. The doubters put things in perspective, keeping the movie from degenerating into a pseudo-philosophical drug trip. Most of the time.

Whenever Chayefsky gets bogged down, Russell saves the day with his sense of humor -- as when a disbelieving doctor stalks off to Radiology, reciting a litany of his qualifications to explain why Jessup can't possibly be regressing. Or when Jessup, in bed with a student, starts to metamorphosize. "You okay, Dr. Jessup?" she asks sleepily, as his forearms go all furry.

About the special effects: a goat with eight eyes, pulsating anatomical transformations, laser trips through time. "Do you think this would've meant a lot more to us if we had done hallucinogens at one time?" mused a woman in the preview audience. Probably so. But that's certainly not a prerequisite to enjoying this trip.