Around water coolers everywhere, people are still talking about Tom Cruise's widely publicized comments late last month against antidepressants. And some experts agree with him.

In an interview with the Today Show's Matt Lauer, the actor strongly condemned the use of psychiatric drugs and claimed that there is no proof that chemical imbalances in the brain drive depression. Since then, psychiatrists across the U.S. have passionately defended the drugs.

The debate over whether Cruise has a point or has no clue will no doubt continue. But a psychiatrist in Britain who has long spoken out against antidepressant use is making many of the same points in an essay published in the July 16 issue of the British Medical Journal.

However, an American expert questions the British psychiatrist's objectivity.

Read WebMD's "Get the Facts about Antidepressant Medications"

'Have to Be Skeptical'

Joanna Moncrieff, who is a senior lecturer in psychiatry at University College London, argues that the clinical evidence does not justify the use of antidepressants -- particularly selective serotonin reuptake inhibitors (SSRIs) -- as the treatment of choice for moderate to severe depression.

SSRIs are the most widely prescribed class of antidepressants and include:Celexa, Luvox, Paxil, Prozac and Zoloft.

"The bottom line is that we really don't have any good evidence that these drugs work," she tells WebMD. "I think we have to be highly skeptical. We have been treating all comers with antidepressants for years now, and we have seen an increase rather than a decrease in depression at the community level."

In the newly published essay, Moncrieff and psychology professor Irving Kirsch, PhD, call on public health officials in Britain to reconsider their policy of recommending antidepressants as the first treatment for moderate to severe depression.

Moncrieff and Kirsch have each published research reviews suggesting that antidepressants are only slightly more effective than placebo for treating depression.

In an analysis published in 2002, Kirsch reviewed 47 studies involving the six most widely prescribed antidepressants. He concluded that 80 percent of the medication response in the patients treated with the antidepressants was duplicated in the patients on placebo. Moncrieff came to a similar conclusion in a review she published in 2001.

Read WebMD's "Different Antidepressants, Same Suicide Risk"

Charge of Bias

But psychiatrist Darrel Regier, MD, MPH, says there is plenty of clinical evidence showing that antidepressants work and that the reviews failed to include important studies showing just that.

Regier, who is director of research for the American Psychiatric Association, noted that Moncrieff is co-founder of a group in the U.K. that questions the very existence of depression and the need to treat it.

"She is of the persuasion that medical disorders are a myth and a social construct, and that there is no biological basis for them," he tells WebMD. "I think what she has done, given her bias, is emphasize the negative [antidepressant] studies and mischaracterize many other ones."

He points out that in a 1997 essay that Moncrieff wrote titled "Psychiatric Imperialism: The Medicalization of Modern Living," she even rejects treating schizophrenic patients against their will.

In the essay, Moncrieff writes that society should instead accept the idea that some schizophrenics "may chose to lead lives that appear bizarre or impoverished."

Read WebMD's "Kids and Antidepressants: A Growing Problem"

Chemical Imbalance Debate

In his July 24 Today Show appearance, Tom Cruise said he did not believe in psychiatry, and he called antidepressants and other psychiatric drugs "very dangerous." Cruise also said that "there is no such thing as a chemical imbalance."

Moncrieff tells WebMD that she was only vaguely aware of Cruise's comments, but she says the actor is "absolutely right" to reject the idea that chemical imbalances are responsible for depression.

The most widely used antidepressants target chemicals within the brain, including serotonin and norepinephrine.

"People who seek help for depression actually have all sorts of different problems, and I don't think that they all share similar brain chemical imbalances," she says. "If we just focus on the chemical serotonin, nobody has been able to show that an abnormality in serotonin has been demonstrated in people with depression."

But once again, Regier says Moncrieff is simply rejecting a large body of evidence that doesn't fit her worldview.

"It is clear that antidepressants which focus on altering the neurotransmission of norepinephrine and serotonin are effective in the treatment of depression," he says. "The brain functions chemically, and the chemical changes that occur with depression are the same, regardless of the reasons for it."

By Salynn Boyles, reviewed by Michael W. Smith, MD

SOURCES: Moncrieff, J. and Kirsch, I. British Medical Journal, July 16, 2005; vol 331: pp 135-137. Joanna Moncrieff, MD, senior lecturer in community psychiatry, University College London, England. Darrel Regier, MD, MPH, director, division of research, American Psychiatric Association.