LONDON (AP) -- When it comes to the placebo effect, it really may be mind over matter, a new analysis suggests.

In a review of recent research, international experts say there is increasing evidence that fake treatments, or placebos, have an actual biological effect in the body.

The doctor-patient relationship, plus the expectation of recovery, may sometimes be enough to change a patient's brain, body and behavior, experts write. The review of previous research on placebos was published online Friday in Lancet, the British medical journal.

"It's not that placebos or inert substances help," said Linda Blair, a Bath-based psychologist and spokeswoman for the British Psychological Society. Blair was not linked to the research. "It's that people's belief in inert substances help."

While doctors have long recognized that placebos can help patients feel better, they weren't sure if the treatments sparked any physical changes.

In the Lancet review, researchers cite studies where patients with Parkinson's disease were given dummy pills. That led their brains to release dopamine, a feel-good chemical, and also resulted in other changes in brain activity.

"When you think you're going to get a drug that helps, your brain reacts as if it's getting relief," said Walter Brown, a clinical professor of psychiatry at Brown and Tufts University. "But we don't know how that thought that you're going to get better actually translates into something happening in the brain."

With growing proof that placebos work, some doctors are trying to figure out how to capitalize on their effects, without being unethical.

Blair said that to be completely honest with patients -- to tell them they were receiving a fake treatment -- would sabotage their belief in the drug, and thus, undermine any potential benefit.

But Brown didn't agree. For certain patients, like those with mild depression or anxiety, he said placebos were likely to work just as well as established therapies.

He said that even if doctors acknowledge they are giving such patients a placebo medication, but say it could be beneficial, "it might just actually work."

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