When he’s not tap dancing on Oprah Winfrey’s couch, Tom Cruise is tap dancing on interviewers.

NY- Is “War of the Worlds” star Tom Cruise lost in space?

The superstar Scientologist flipped out on the “Today” show yesterday, pompously lecturing Matt Lauer about the evils of psychiatry – and scolding actress Brooke Shields for taking anti-depressants.

“You don’t know the history of psychiatry,” the actor arrogantly told the newsman. “I do.”

Cruise, 42, was on the NBC morning show to talk about his upcoming sci-fi flick and his quickie engagement to ingénue Katie Holmes, 26.

But the interview took a bizarre turn when Lauer questioned Cruise on critical comments he’s made about Shields and her memoir about overcoming postpartum depression.

Cruise defended his claim that Shields was wrong to take depression pills to cure a crippling case of the baby blues after the the birth of her daughter.

“The things I’m saying about Brooke is that there’s misinformation, okay?” he said.

“And she doesn’t understand the history of psychiatry. She doesn’t understand in the same way that you don’t understand it, Matt.”

The high school dropout launched into a diatribe about mental illness – calling psychiatry a “pseudoscience” and anti-depressants “very dangerous.”

He insisted there’s no such thing as a chemical imbalance and argued that mood disorders can be cured with “vitamins, exercise and various things.”

He didn’t say whether one of those things is Scientology, the religion that says humans are plagued by the souls of dead aliens who invaded the planet 75 million years ago.

Cruise interrupted and cut off Lauer as he tried to present the other side of the argument.

“Matt, Matt, Matt, you don’t even – you’re glib,” he said.

With a $128 million movie riding on his popularity, Cruise’s attack on Shields and well-established science could be risky business.

Coupled with his over-the-top courtship of Holmes, it could be the biggest career misstep since fellow Scientologist John Travolta made “Battlefield Earth.”

His proselytizing is also angering psychiatrists who fear the Hollywood top gun could undo decades of work to remove the stigma from mental illness and psychiatric treatment.

“The illnesses we treat – anxiety, depression – are very real illnesses,” said Dr. John Scully, medical director of the American Psychiatric Association.

“The treatments work. We have demonstrated that through robust scientific study.”

Cruise’s views on psychiatry are so extreme and devoid of scientific proof, “it’s a little like talking to somebody who claims the world is flat,” Scully said.

Dr. Margaret Spinelli of the New York Psychiatric Institute’s maternal mental health program said, “science at every level” has demonstrated that postpartum depression stems from a chemical imbalance that medication can correct in 80% of the cases.

“Brooke Shields did a great service for women by writing the book and talking about her illness,” Spinelli said. “She should be getting praise, not pushed down for it.”

Shields’ publicist could not be reached for comment but after Cruise’s first swipe at her last month, she issued a statement calling his remarks “outrageous.”

“Tom should stick to saving the world from aliens and let women who are experiencing postpartum depression decide what treatment options are best for them,” she said.

MORNING SHOWDOWN

Excerpts from Tom Cruise’s faceoff with NBC’s Matt Lauer about Brooke Shields’ battle with depression and psychiatric drugs like Ritalin:

Lauer: Tom, if she said that this particular thing helped her feel better, whether it was the antidepressants or going to a counselor or psychiatrist, isn’t that enough?

Cruise: Matt, you have to understand this. Here we are today, where I talk out against drugs and psychiatric abuses of electric shocking people against their will, of drugging children with them not knowing the effects of these drugs. Do you know what Aderol is? Do you know Ritalin? Do you know now that Ritalin is a street drug? Do you understand that?

Lauer: Aren’t there examples, and might not Brooke Shields be an example, of someone who benefited from one of those drugs?

Cruise: All it does is mask the problem, Matt. And if you understand the history of it, it masks the problem. That’s what it does, that’s all it does. You’re not getting to the reason why. There is no such thing as a chemical imbalance.

Lauer: But aren’t there examples where it works?

Cruise: Matt, Matt, Matt, you don’t even – you’re glib. You don’t even know what Ritalin is. If you start talking about chemical imbalance, you have to evaluate and read the research papers on how they came up with these theories, Matt, okay? That’s what I’ve done.