Placebo can spark physical change, study finds

BY OLIVER MOORE Globe and Mail Update
Wednesday, May 1  Online Edition, Posted at 9:49 AM EST

A placebo not only has the power to make patients feel better, it may also be able to cause the same physiological change as the drug it replaces, a team of researchers led by a Toronto neuropsychiatrist says.

Researchers at the University of Texas Health Science Center found that depressed people given a placebo exhibited changes in their brain that were remarkably similar to those given fluoxetine (marketed under the brand name Prozac).

"What we found is that patients who responded to placebo and those who responded to an antidepressant had similar, but not identical, metabolic changes in cortical (thinking) and limbic-paralimbic (emotional) regions [of their brains]," University of Toronto Professor of Neurology and Psychiatry Dr. Helen Mayberg says.

She cautions, though, that the effects may not be permanent. "If you respond to a placebo, this may mean that your brain has an inherent capacity to heal itself but it is likely a short-term effect."

Researchers administered treatment to 17 depressed and hospitalized men over a six-week period. In the double-blind controlled experiment, neither the patients nor the doctors knew who had received the drug and who had been given the placebo. Of the 15 men who completed the study, eight had experienced a improvement in their symptoms. Four of them had been taking the bona fide drug and four had been taking a placebo.

"Our findings are consistent with the well-recognized placebo phenomenon that 'expectation' that a treatment will be helpful is a critical part of the therapeutic relationship between a patient and their doctor," Dr. Mayberg said.

The study broke new ground, though, in showing that patients exhibited similar changes in their brains. Patients on active medication, however, did show "additional changes" in their brain stem, striatum and hippocampus.

The clinical study published in the May issue of the American Journal of Psychiatry (Vol. 159, #5) is being called the first to identify, using positron emission tomography (PET), the specific brain regions that change with placebo response and compare them to brain regions that change with active drug intervention.

All subjects were put on active medication at the end of the six-week experiment, so it is not known if the placebo effect would have continued.


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